Experts have called for the worldwide eradication of cervical cancer, but this is not likely to happen for a long time
Significant progress has been made to eliminate cervical cancer in developed countries
The overwhelming burden of cervical cancer falls disproportionately on women in low- to middle-income countries (LMIC)
LMIC have relatively low levels of awareness of cervical cancer, patchy prevent programs and limited treatment options
Over 80% of cervical cancer cases and deaths occur in LMIC
Cervical cancer is the fourth most common cancer in women worldwide
In 2018 there were an estimated 680,000 new cases and 311,000 deaths from the disease worldwide
Cervical cancer is caused by sexually acquired infection from high-risk strains of the human papilloma virus (HPV)
The majority of women will be infected with HPV at some point in their life
HPV also causes genital warts and cancers of the head and neck and is also linked to cancers of the anus, vulva, vagina, penis and oropharynx
HPV vaccines protect against 70% of cervical cancers and about 90% of genital warts
Regular screening is also recommended to reduce the incidence of cervical cancer
Challenges to eradicate cervical cancer globally
Cervical cancer is a killer disease, which only affects women. It affects women of all ages from schoolgirls to grandmothers, but it is significantly more prevalent between the ages of 30 and 45.
The cervix, also known as the neck of the womb, connects a woman's womb and her vagina.
Lancet study raises hope of eradicating cervical cancer
Research findings published in the June 2019 edition of The Lancetsuggest that HPV vaccination, which has been available to adolescent girls in wealthy developed countries since 2007, has led to a dramatic reduction in the number of HPV infections, precancerous cervical lesions and anogenital warts and provides hope of eradicating cervical cancer. Marc Brisson, Professor in the Department of Social and Preventative Medicine, Laval University, Canada, who led the research - a meta-analysis of over 65 former studies covering 60m people - said: "We will see reductions [in cervical cancer] in women aged 20-30 within the next 10 years, and eradication of the disease [defined as <4 cases per 100,000] might be possible if sufficiently high vaccination coverage can be achieved and maintained". Over the past two decades, the incidence rates of cervical cancer in developed countries have fallen significantly, and between 1955 and 1992, the incidence rate of the disease decreased 70% in the US. These falls are attributed to effective nationwide screening.
Cervical cancer is the fourth most common cancer in women worldwide and second for women between 15 and 44. In 2018 there were an estimated 680,000 new cases and 311,000 deaths from the disease worldwide. The overwhelming majority of cases are caused by two specific strains of the human papilloma virus (HPV). HPV infection and early cervical cancer typically do not present noticeable symptoms, and cervical cancer may take 20 years or longer to develop after an HPV infection. The overwhelming global burden of the disease falls disproportionately on women in low- to middle income countries (LMIC). There is a significant and growing gap in the incidence and mortality rates of cervical cancer between developed nations and LMIC. Despite international efforts, it seems unlikely that this gap will be narrowed in the medium term.
In this Commentary
This Commentary describes the spread of HPV, the vaccines developed to prevent infection from specific high-risk strains of the virus and recommended vaccination regimens. We describe the nature and significance of complementary screening programs and present evidence to suggest that women who fail to get screened are more likely to contract cervical cancer in later life than women who are screened. HPV vaccination programs are more prevalent in developed economies and are associated with a significant reduction in the incidence rates of cervical cancer. This suggests that the battle to eliminate cervical cancer is being won in some wealthy developed nations. Australia is positioned to become the first country in the world to eliminate cervical cancer. Despite substantial global efforts to reduce the incidence rates of cervical cancer, the gap in preventing, diagnosing and treating the disease between wealthy nations and LMIC is significant and growing. We conclude by suggesting that to eradicate cervical cancer, screening and prevention programs must be linked to easily accessible and effective treatment.
The spread of HPV
Over 70% of cervical cancer is caused by two high-risk strains of HPV. Most women will contract HPV at some stage during their life, but this usually clears-up on its own without the need for any treatment. HPV is most commonly spread during vaginal, anal or oral sex. The virus can be passed even when an infected person has no signs or symptoms. If you are sexually active you can get HPV, even if you only have sex with one partner. Notwithstanding, the risk increases with the number of new sexual partners and their sexual histories. You also can develop symptoms years after you have sex with someone who is infected. This makes it hard to know when you first became infected.
The US Food and Drug Administration (FDA) has approved three vaccines, which prevent infection with disease-causing HPV types. These are Gardasil, Gardasil 9 and Cervarix. All three vaccines prevent infection with HPV types 16 and 18 in women who have not already been infected by these types. These are two high-risk HPV’s that cause about 70% of cervical cancers and an even higher percentage of some of the other HPV-caused cancers. Gardasil also prevents infection with HPV types 6 and 11, which cause 90% of genital warts. Gardasil 9 prevents infection with the same four HPV types, plus five additional cancer-causing types.
About 79m Americans are currently infected with HPV, with roughly 14m people becoming newly infected in the US each year. In the UK, HPV is present in one in three people and 90% of individuals will come into contact with some form of the virus in their lifetime. About 80% of sexually active people are infected with HPV at some point in their lives, but most people never know they have the virus. Whitfield Growdon, a surgical oncologist at the Massachusetts General Hospital and professor at the Harvard University Medical School describes the HPV vaccination as, “one of the most meaningful interventions for reducing cervical cancer”; see video below.
Who should get vaccinated?
All girls and boys aged between 11 and 12 should get the HPV vaccination. Every year in the US, over 13,000 males contract cancers caused by HPV. Catch-up HPV vaccines are recommended for girls and women through the age of 26, and for boys and men through the age of 21, if they did not get vaccinated when they were younger. HPV vaccination is also recommended for the following people, if they did not get vaccinated when they were younger: (i) young men who have sex with men through the age of 26, (ii) young adults who are transgender through the age of 26 and (iii) young adults with certain immunocompromising conditions (including HIV) through the age of 26.
Early cervical cancer is asymptomatic
Because early cervical cancer is asymptomatic, it is important for women to have regular Papanicolaou (Pap) smears - also called Pap tests - to detect any precancerous changes in the cervix that might lead to cancer. This is in addition to the HPV vaccination. In England women are invited to have Pap smears every three years between the ages of 25 and 49, when rates of cervical cancer are at their peak, and every five years between 50 and 65. Other international screening guidelines recommend that women aged 21 to 29 have a Pap smear every three years. Women aged 30 to 65 are advised to continue having a Pap test every three years, or every five years if they also combine it with an HPV DNA test. Women over 65 can stop testing if they have had three consecutive normal Pap tests, or two HPV DNA and Pap tests with no abnormal results.
The HPV DNA test determines the most likely cause of cervical cancer by looking for pieces of DNA in cervical cells and is recommended for women over 30 and not for women under 30. This is because women in their 20s tend to be more sexually active and therefore are more likely (than older women) to have an HPV infection that will go away on its own. Results of an HPV DNA test carried out on a woman in her 20s is not as significant as in and older woman and also may be confusing. The HPV DNA test can also be used in women who have slightly abnormal Pap test results to find out if they might need more testing or treatment.
The Pap smear/test
The Pap smear or Pap test is a method of cervical screening used to detect potentially precancerous and cancerous processes in your cervix. During the routine procedure, cells from your cervix are gently scraped away and then examined for abnormal growth. Abnormal findings are often followed-up by more sensitive diagnostic procedures and if warranted, by interventions that aim to prevent progression to cervical cancer. Detecting cervical cancer early with a Pap smear significantly increases the chances of a cure. A Pap smear can also detect changes in your cervical cells, which suggest you might develop cancer in the future. In the two videos below Growdon describes the Pap smear and other tests for diagnosing cervical cancer.
What is a Pap smear test?
Diagnostic tests for cervical cancer
Women failing to have the Pap test are 6-times at greater risk of cervical cancer
There is evidence to suggest that women over 50 who fail to have a regular Pap smear have a much higher risk of developing cervical cancer compared with other women the same age who have a history of regular screening. Research carried out by Cancer Research UKand reported in 2014 investigated the utility of regular cervical cancer screening after 50, and whether 64 was an appropriate age to stop screening and concluded “yes” and “yes”. The study compared the screening history of 1,341 women between 65 and 83 in England and Wales who were diagnosed with cervical cancer over a five-year period, with 2,646 women of the same age without the disease. Findings suggest that women who did not attend screening tests were six times more likely to develop cervical cancer between 65 and 83 compared with women that did.
Australian the first country to eradicate cervical cancer
Australia is well positioned to become the first country in the world to eradicate cervical cancer. This is largely due to national vaccination and screening programs, which could see the disease effectively eliminated as a public health issue within the next two decades. In 2007, Australia launched a national publicly-funded school immunisation program to reduce HPV, which complemented a national cervical cancer screening program that was launched in the 1990s. These have been shown to reduce the incidence of cervical cancer and significantly increase early diagnosis when the disease is curable.
A research paper about the Australian initiative published in the January 2019 edition of The Lancet Public Health concludes that, “the annual incidence of cervical cancer in Australia is likely to decrease to fewer than six new cases per 100 000 women by 2020 (range 2018–22) and to fewer than four cases per 100 000 women by 2028 (2021–35). The annual incidence of cervical cancer could decrease to one new case per 100 000 by 2066 (2054–77) if the existing HPV-based screening program continues in cohorts who are offered the nonavalent vaccine”; [a nonavalent vaccine works by stimulating an immune response against nine different antigens, such as nine different viruses or other microorganisms]. According to Suzanne Garland, Professor and Clinical Director of Microbiology and Infectious Diseases at the Royal Women’s Hospital, Melbourne, Australia, who led the research, “within 40 years the number of new cases of cervical cancer [in Australia] is projected to drop to just a few”.
The two worlds of cervical cancer
Global efforts to reduce the incidence rates of cervical cancer have focused on HPV vaccination and the Pap test. Although experts are optimistic about eliminating cervical cancer in developed nations, which have advanced healthcare systems and extensive HPV vaccination, screening and treatment programs, they are significantly less sanguine about eradicating the disease in LMIC where there are relatively low levels of awareness of cervical cancer, a dearth of preventative strategies, limited expertise and a narrow band of treatment options. This results in the disease being identified late when it is at an advanced stage, which leads to higher rates of morbidity and death. Indeed, 85% of all cases and cervical cancer deaths occur in LMIC, where the death rate is 18 times higher than in wealthy nations.
Cervical cancer a challenge for LMIC
The gap in preventing, diagnosing and treating cervical cancer between wealthy nations and LMIC is described in a paper published in the November 2017 edition of Gynecologic Oncology Reportsand suggests that, “Developing countries continue to bear a disproportionate percentage of the global cervical cancer burden. Investigations into the growing gap in incidence and mortality between developed nations and LMIC have cited persistent financial, infrastructural and educational limitations as key drivers. Pervasive lack of access to both preventative and definitive care has left a substantial portion of cervical cancer patients with minimal options for disease management”.
WHO strategy to eliminate cervical cancer
Recognising this disparity, in 2018, the Director-General of the World Health Organization (WHO) announced a call to action for the eradication of cervical cancer as a public health problem. In January 2019, the Executive Board of the WHO requested the Director General to develop a draft strategy to accelerate cervical cancer elimination, with clear targets for the period 2020 - 2030.
Vaccination and screening must be linked to effective therapies
The expansion of screening programs for cervical cancer in LMIC is only part of the answer to closing the gap with developed nations and eradicating cervical cancer globally. It is imperative that screening is linked to increased access to effective treatment for women with cervical cancer, particularly in its early stages when it is still curable. In LMIC there is often not only reduced access to preventive HPV vaccines and screening, but limited access to treatment and trained personnel. Notwithstanding, there is evidence to suggest that, in LMIC less-invasive and less–resource-intensive treatment options can be effective and are increasingly being made available.
Late presentation of cervical cancer in LMIC
Women from LMIC generally seek treatment for cervical cancer only after the presentation of symptoms when the disease is advanced and challenging to treat. Also, they often lack awareness of the disease and ways to prevent it. Further, in some regions of the world, cultural norms and myths about cervical cancer pose additional barriers to prevention. Despite such obstacles, the disease can be prevented at low cost by healthcare providers employing relatively simple techniques to screen women for precancerous conditions and treat abnormal tissue early. Among the most promising low cost and low-tech screening alternatives to the Pap smear, is visual screening, which only requires either simple vinegar or iodine solutions and the eye of a trained healthcare provider to spot abnormal tissue.
Screening linked to effective therapy
Increasingly, these simply tests are being linked with effective treatment. Increasingly, in LMIC relatively cheap and simple therapies are being used to either destroy or remove abnormal cervical tissue, depending on the severity, location and size of the affected area. Two such procedures include cryotherapy and loop electrosurgical excision procedure (LEEP). The former uses extremely low temperatures to destroy abnormal tissue and requires no electricity. The latter involves using a thin wire to remove lesions in the affected area. While this procedure requires more medical equipment than cryotherapy, it allows tissue to be removed for analysis, reducing the possibility that advanced cancer will go unnoticed. Although many LMIC have had cervical cancer prevention programs and simple treatment strategies in place for some time, some have failed to reduce death rates of the disease.
Radiotherapy and cervical cancer in LMIC
Research findings published in the May 2019 online edition of The Lancet Oncologysuggest that the availability of radiotherapy in LMIC (where gross national income is <US$12,000 a year) would generate millions of productive life years and billions of dollars in economic benefits for the patients' families and communities. The study suggests that implementing a 20-year strategy for radiotherapy to treat cervical cancer in LMIC between 2015 and 2035, in parallel with an HPV vaccination program, would save the lives of some 9.4m women and provide a net benefit to economies of US$151.5bn as a direct result of women living longer and more productive lives.
According to Danielle Rodin, lead author and Radiation Oncologist at the Princess Margaret Cancer Centre, University of Toronto, Canada, "Vaccination is hugely important, but we can't neglect the millions of women who are contracting cervical cancer and dying in pain without access to treatment. These are women who have curable cancers: even advanced cervical cancer can be cured with radiotherapy. The possibility exists to make this treatment universally available". Radiation therapy makes small breaks in the DNA inside cells. This stops cancer cells from growing and dividing and causes them to die. Unlike cisplatin therapy, [an anti-cancer ("antineoplastic" or "cytotoxic") chemotherapy], which usually exposes the whole body to cancer-fighting drugs, radiation therapy is usually a local treatment.
According to the 2019 Lancet Oncology study, HPV vaccination would result in a 3.9% reduction in cervical cancer incidence over the 20-year study period; assuming a best-case scenario of vaccinating every 12-year-old girl in the world starting in 2014. By 2072, when the first vaccinated cohort reaches 70, there would be a 22.9% reduction in incidence, still leaving 41.6m in need for therapy over that time period.
“We know that when administered together (chemoradiation) you can give lower doses of both and get a better kill-rate on the tumour. This is now the backbone of cervical cancer therapy”, says Growdon; see video below.
Abu Dhabi’s endeavours to reduce cervical cancer
For some years, experts have discussed religious and cultural barriers to cervical cancer screening and drew attention to the relatively low levels of cervical cancer awareness and screening for women in Middle Eastern Arab countries. Meta-analysis of cervical cancer studies conducted in Arab countries between January 2002 and January 2017 and published in the December 2017 edition of Nursing & Health Sciences,suggest that in Arab speaking countries there tends to be, “low knowledge of and perceptions about cervical screening among Arab women, the majority of whom are Muslim. Factors affecting the uptake of cervical cancer screening practices were the absence of organized, systematic programs, low screening knowledge among women, healthcare professionals' attitudes toward screening, pain and embarrassment, stigma, and sociocultural beliefs”.
The success of HPV vaccination in Abu Dhabi and the UAE
Notwithstanding, there are signs that this is changing. Leading such changes is Abu Dhabi of the United Arab Emirates (UAE). Over a decade ago, a mandatory free HPV vaccination program for school girls was introduced by Abu Dhabi’s Ministry of Health and Prevention and extended in 2013 to include women between 18 and 26. Also, the Ministry recommends that woman aged 25 to 65 years get a Pap smear every three to five years. Since 2018, HPV vaccinations have been provided free and compulsory for all school girls in Dubai and the Northern Emirates following a campaign to raise awareness.
Although the UAE is among the few countries to have relatively low incidence rates of cervical cancer, the disease still ranks as the third most frequent cancer among women in the UAE and the third most frequent cancer among women between 15 and 44. Estimates suggest that every year, 93 women are diagnosed with cervical cancer and 28 die from the disease in the UAE. Although Abu Dhabi is successfully leading the fight against cervical cancer and provides a roadmap for others to follow, the incidence of cervical cancer in the Middle East generally is expected to more than double by 2035 (>33,000 cases) and be responsible for more than 18,000 deaths. In some countries including Morocco and Saudi Arabia, low societal awareness and relatively low levels of screening results in about one in four women with HPV.
As cervical cancer screening and prevention programs have been growing and extending their reach, so increases the need to provide access to effective treatment. Despite growing awareness of the disease and global efforts to increase availability of appropriate resources, cervical cancer remains prevalent particularly in LMIC where effective treatment has not become widespread. In many LMIC, the default option is often to do nothing, which results in certain death. Researchers and policy makers should consider focusing their activities on how to best to reconcile the use of existing resources with the expected impact on the quantity and quality of life. Although gaps in oncological resources and barriers to treatment still exist, the good news is that there is increased political will and international attention to improve access to safe and effective treatment of cervical cancer. Notwithstanding, eradicating the disease globally appears to be more of a theoretical possibility than a medium term reality.
A 2018 clinical study in China is the first to use CRISPR to edit cells inside the human body in an attempt to eliminate the human papilloma virus (HPV) and is hugely significant for millions of women
Nearly all sexually active people get an HPV virus at some point in their lives and persistent high-risk HPV infections are the main cause of cervical cancer
Respectively 34,800 and 256,000 women in the UK and US live with cervical cancer and each year about 3,200 and 12,200 new cases of cervical cancer are diagnosed in the UK and US respectively nearly all related to HPV
Cervical cancer is increasing in older women not eligible for the HPV vaccine and not availing themselves of Pap test screening programs
A new study suggests that cervical cancer mortality among older women could increase by 150% in the next 20 years
CRISPR positioned to eliminate human papilloma viruses that cause cervical cancer
January 2018 marked the beginning of the first CRISPR clinical study to attempt to edit cells while they are in the body of women in the hope to eliminate the human papilloma virus (HPV), which is the main cause of cervical cancer. The study, led by Zheng Hu of the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong, China, is the first to edit human cells while inside the body. Zheng Hu will apply a gel that carries the necessary DNA coding for the CRISPR machinery to the cervixes of 60 women between the ages of 18 and 50. The study’s aim is to prevent cervical cancers by targeting and destroying the HPV genes that cause tumor growth while leaving the DNA of normal cells untouched. Current estimates suggest that every year 527,624 women are diagnosed with cervical cancer and 265,672 die from the disease. Zheng Hu’s study is expected to be completed by November 2018 and findings reported in January 2019.
In this Commentary
This Commentary describes the Chinese CRISPR study and the etiology and epidemiology of cervical cancer. It also describes the current cervical cancer vaccination possibilities and the challenges they face. Further, the significance of the Chinese study is demonstrated by an English study, published in December 2017 in the Lancet Public Health, which warns that although HPV vaccination programs have significantly reduced the incidence of cervical cancer among young women, the incidence of the disease is increasing significantly among older women who do not qualify for the cervical cancer vaccine, and fail to avail themselves of regular Pap tests (A Pap test is a simple, quick and essentially painless screening procedure for cancer or precancer of the uterine cervix). The latter part of the Commentary describes advances that CRISPR technology has made over the past decade as well as describing its main ethical and technical challenges.
Human papilloma virus (HPV)
There are over 200 different types of HPV related viruses. Viruses are the etiological agents of approximately 15% of human cancers worldwide, and high-risk HPVs are responsible for nearly 5% of cancers worldwide. It is estimated that about 75% of the reproductive-age population has been infected with 1 or 2 types of genital HPV. About 79m Americans are currently infected with HPV, and about 14m people become newly infected each year. The American Centers for Disease Control and Preventionestimates that more than 90 and 80% of sexually active American men and women respectively will be infected with at least one type of HPV at some point in their lives. Most HPV infections are harmless, they last no more than 1 to 2 years, and usually the body clears the infections on its own. More than 40 HPV types can be easily spread by anal, oral and vaginal sex. About 12 HPV types are high risk, and it is estimated these persist in only about 1% of women. However, a central component of the association between HPV and cervical carcinogenesis is the ability of HPV to persist in the lower genital tract for long periods without being cleared. These persistent high-risk types of HPV can lead to cell changes, which if untreated, may progress to cancer. Other HPV types are responsible for genital warts, which are not sexually transmitted.
Etiology of cervical cancer
“The way that the HPV causes cancer informs us about how cancer occurs in other settings. Virus particles insert foreign DNA into a person’s normal cells. This virus then turns off the “off-switch” and allows the oncogenes [Genes that can transform a cell into a tumor cell] to progress unchecked and create an oncogenic virus. So, in this case the 'insult' is known: it’s an HPV virus. However, in many circumstances we’re not sure what that initial switch is that upsets the balance between a tumor suppressor and an oncogene,” says Whitfield Growdon, of the Massachusetts General Hospital and Professor of Obstetrics, Gynecology and Reproductive Biology at the Harvard University Medical School: see video below:
HPV and cervical cancer
The association of risk with sexual behavior has been suggested since the mid-19th century, but the central causal role of HPV infection was identified just 40 years ago. HPV infection is the main etiologic agent of cervical cancer. 99% of cervical cancer cases are linked to genital infection with HPV and it is the most common viral infection of the reproductive tract. HPV types 16 and 18 are responsible for about 70% of all cervical cancer cases worldwide. Further, there is growing evidence to suggest that HPV also is a relevant factor in other anogenital cancers (anus, penis, vagina and vulva) as well as head and neck cancers. The importance of prevention and cervical cytological screening was established in the second half of the 20th century, which preceded and even advanced etiologic understanding.
Epidemiology of cervical cancer
Cervical cancer is one of the most common types of gynecological malignancies worldwide. It ranks as the 4th most frequent cancer among women in the World, and the 2nd most common female cancer in women between 15 and 44. According to the World Health Organization there were some 630m cases of HPV infections in 2012, and 190m of these led to over 0.5m new diagnoses of cervical cancer. The World has a population of some 2,784m women aged 15 and older who are at risk of developing cervical cancer. Each year about 3,200 and 12,200 new cases of cervical cancer are diagnosed in the UK and US respectively; nearly all related to HPV. There is estimated to be 34,800 and 256,000 women in the UK and US respectively living with cervical cancer. Each year some 890 and 4,200 women die from cervical in the UK and US respectively.
HPV vaccines, which prevent certain types of HPV infections, are now available to females up to the age of 26, and have the potential to reduce the incidence of cervical and other anogenital cancers. “Vaccinations work by using your own immune system against foreign pathogens such as viruses and bacteria. Vaccination against some high risk sub-types of cancer-causing HPV viruses is one of the most meaningful interventions we’ve had since the development of the Pap test,” says Growdon: see video below.
Gardasil and Cervarix
Gardasil, an HPV vaccine developed by Merck & Co., and licenced by the US Food and Drug Administration (FDA) in 2006, was the first HPV vaccine recommended for girls before their 15th birthday, and can also be used for boys. In 2008 Cervarix, an HPV vaccine manufactured by GlaxoSmithKline, was introduced into the UK’s national immunization program for girls between 12 and 13. Both vaccines have very high efficacy and are equally effective to immunise against HPV types 16 and 18, which are estimated to cause 70% of cervical cancer cases. Both vaccines significantly improve the outlook for cervical cancer among women living in countries where it is routinely administered to girls before they become sexually active. “Both Gardasil and Cervarix vaccines have been shown to be incredibly effective at preventing the development of high-grade dysplasia, which we know, if left unchecked, would turn into cervical cancer,” says Growdon: see video above.
Gardasil also protects against HPV types 6 and 11, which can cause genital warts in both men and women. Second-generation vaccines are under development to broaden protection against HPV. In 2014 the FDA approved Gardasil 9, an enhanced vaccine, which adds protection against an additional 5 HPV types that cause approximately 20% of cervical cancers.
Despite the availability of prophylactic vaccines, HPVs remain a major global health challenge due to inadequate vaccine availability and vaccination coverage. Despite the promise, vaccine uptake has been variable in developed nations, and limited in developing nations, which are most in need. The available vaccines are expensive, require a cold chain to protect their quality, and are administered in 2 to 3 doses spanning several months. Thus, for a variety of practical and societal reasons (e.g., opposition to vaccination of young girls against a sexually transmitted agent, fear of vaccination), coverage, particularly in the US has been lower than would be optimal from a public health perspective.
Notwithstanding, a study referred to above and published in the Lancet Public Healthsuggests cervical cancer cases are expected to fall by 75% among young women for whom vaccination is now the norm. Death from cervical cancer among the generation who were 17 or younger in 2008 when the UK vaccination program was introduced is expected to virtually disappear.
Challenges for older women
Notwithstanding the success of HPV vaccines for young women, there are continuing challenges for older women who, because of their age, do not qualify for HPV vaccines, and do not attend their Pap screening test when invited. “Pap tests involve scraping the cervix on the outside for cells, which then udergo microscopic examination. Today this is carried out by a computer. Further examination is carried out by a cytopathologist who determines status . . . . . . . . . . Pap tests do not diagnose cancer, but tell you whether you are at high risk of either having pre-cancerous or cancerous cells. Actual diagnosis of cervical cancer involves a colposcopy. This is a simple procedure, which uses a specific type of microscope called a colposcope to look directly into the cervix, magnify its appearance, and helps to take biopsies of abnormal areas,” says Growdon: see videos below.
What is a Pap smear test?
Diagnostic tests for cervical cancer
Older women and Pap tests
Pap tests, which are offered by NHS England to women between 25 and 64, is the most effective way of preventing cervical cancer; yet data show that in 2016 there was a significant drop in Pap test screening as women’s age increased. If such screening covered 85% of women, it is estimated that it would reduce deaths from cervical cancer by 27% in 5 years, and the diagnosis of new cases of cervical cancer by 14% in 1 year. According to the authors of the 2017 Lancet study, “The risk of acquiring an HPV infection that will progress to cancer has increased in unvaccinated individuals born since 1960, suggesting that current screening coverage is not sufficient to maintain – much less reduce – cervical cancer incidence in the next 20 years.”
Cervical cancer projected to increase in older women
Over the next 2 decades, diagnoses of cervical cancer in women between 50 and 64 are projected to increase by 62%, which could increase mortality from the disease by nearly 150%. “The main reason for this is that the population is ageing and women currently 25-40 will not benefit from vaccination – and they are in the age range where the likelihood of getting an HPV infection is quite high,” saidAlejandra Castanon one of the authors of the Lancet study.
Chinese study extends CRISPR technology
The Chinese study mentioned above to eliminate the HPV virus employs an innovative extension of CRISPR, which is a ‘game-changing’ technology. Over the past decade CRISPR has become a significant tool for genetic manipulation in biomedical research and biotechnology.
CRISPR and genome editing
CRISPR is a complex system that can recognize and cut DNA sequences in order to provide organisms a strong defence against attacks and make them immune from further assaults. CRISPR has been adapted for both in vitro and in vivo use in eukaryotic cells to perform highly selective gene silencing or editing. Eukaryotic cells are those that contain a nucleus surrounded by a membrane and whose DNA is bound together by proteins into chromosomes. CRISPRs are specialized stretches of DNA, and"CRISPR-Cas9" provides a powerful tool for precision editing due to its highly efficient targeting of specific DNA sequences in a genome, and has become the standard for genetic editing. Cas9 protein is an enzyme that acts like a pair of molecular scissors capable of cutting strands of DNA. The genomes of organisms encode messages and instructions within their DNA sequences. Genome editing involves changing those sequences, thereby changing the messages. This is achieved by making a break in the DNA, and tricking a cell's natural DNA repair mechanisms to make desired changes; CRISPR-Cas9 provides a means to do this. The technology’s ease of use and low cost have made it popular among the scientific community, and the possibility of its use as a clinical treatment in several genetically derived pathologies has rapidly spread its significance worldwide.
Changing ethical concerns
Despite CRISPRS promise there have been significant ethical concerns to genome editing, which center around human germline editing. This is because germline editing entails deliberately changing the genes passed on to children and future generations; in other words, creating genetically modified people. The debate about genome editing is not a new one, but has regained attention following the discovery that CRISPR has the potential to make such editing more accurate and even "easy" in comparison to older technologies. As of 2014, there were about 40 countries that discouraged or banned research on germline editing, including 15 nations in Western Europe. There is also an international effort, launched in December 2015 at the International Summit on Human Gene Editing and led by the US, UK, and China, to harmonize regulation of the application of genome editing technologies.
After initially being opposed to using CRISPR in humans, in June 2016, the US National Institutes of Health advisory panel approved the technology for a study designed to target three types of cancer and funded by the Parker Institute for Cancer Immunotherapy at the University of Pennsylvania. In 2017 the UK approved the use of CRISPR for research in healthy human embryos.
Soon after scientists reported that CRISPR can edit DNA in 2012, experts raised concerns about “off-target effects,” meaning either CRISPR changes a gene scientist did not want changed or it fails to change a gene that they do. Although CRISPR-Cas9 is known for its precision a study, published in 2017 in the journal Nature Methods, raised concerns that because of the potential for “off-target effects” testing CRISPR in humans may be premature. Non-intended consequenes can happen because one molecule in the CRISPR system acts like a “molecular bloodhound”, searching the genome until it finds a match to its own sequence of genetic letters; but there are 6bn genetic letters of the human genome, which suggests that there may be more than one match. Scientists anticipate and plan for this by using a computer algorithm to predict where such flaws might occur, then they search those areas to see if such off-target effects did occur. Notwithstanding such procedures and despite CRISPR’s precision, substantial efforts still are required to make the technology a common device safe for human clinical treatments.
Advances using CRISPR
The first clinical study using CRISPR began in October 2016 at the West China Hospital in Chengdu. Researchers, led by oncologist Lu You from Sichuan University, removed immune cells from the blood of a person with lung cancer, used CRISPR to disable a gene called PD-1, and then returned the cells to the body. This study is part of a much larger CRISPR genome editing revolution. Today, there are about 20 human clinical studies taking place using CRISPR technology most of which are in China. Different studies focus on different cancers including, breast, bladder, oesophageal, kidney, and prostate cancers. Further, a 2017 paper published in the journal Celldescribes a number of innovative ways CRISPR being used; including editing cells while inside the body.
Despite the efficacy of HPV vaccines, immunization against cervical cancer still has significant challenges. Vaccines only target young people before they become sexually active, and are not recommended for slightly older and sexually active women. There is an urgent and growing concern about older women therefore who were not eligible for HPV vaccination, and are not availing themselves of regular Pap tests, and in whom the incidence of cervical cancer is increasing significantly. This makes Zheng Hu’s clinical study extremely important because it holds out the potential to substantially dent this large and rapidly increasing burden of cervical cancer.
Human Papillomavirus (HPV) is a common virus that is spread through sexual contact. Most of the time HPV has no symptoms so people do not know they have it. There are approximately 40 types of genital HPV. Somes types can cause cervical cancer in women and can also cause other kinds of cancer in both men and women. Other types can cause genital warts in both males and females.
The HPV vaccine works by preventing the most common types of HPV that cause cervical cancer and genital warts. It is given as a 3-dose vaccine.
Cervical cancer is an unusual and exceptional disease. The human papilloma virus (HPV) is extremely common in the human population and is impossible to entirely irradicate. The UK cervical vaccine program holds great promise for preventing cervical infections caused by the papilloma virus. Infections by the papilloma virus are not cervical cancer. Many people have cervical infections caused by the papilloma virus, but they do not have cervical cancer. Although the papilloma virus is a necessary pre-requisite for cervical cancer, it is not the only factor in the disease. With the cervical vaccination program we can look forward to a time when the incidence of cervical cancer will be very low.
The human papilloma virus is transmitted through genital contact, most often during vaginal and anal sex. Also, HPV may be transmitted during oral sex and genital-to-genital contact.
At some point in their lives, nearly 50 per cent of all men and more than 75 per cent of all women are infected with HPV. Most HPV infections in young females are temporary and have little long-term significance. Currently, approximately 20 million Americans are infected with HPV and another six million become newly infected each year.
HPV tests on the market are only used to help screen women at certain ages.
Each year worldwide, there are an estimated 0.5 million cases of cervical cancer diagnosed and 270,000 deaths from the disease.
The US Center for Disease Control and Prevention recommends the use of three shots of the HPV vaccine in females aged between nine and 26 years.