HPV and Carcinoma of the Cervix
Domlur, Bengaluru Feb 14, 2017
Carcinoma of the Uterine Cervix is a global health issue with special interest to countries like India. Approximately 85% of cervical cancers occur in less developed regions around the world, representing 12% of women’s cancers in those regions. It is also the second most common cancer worldwide in women between the ages of 15 and 44 years. About 87% of deaths resulting from cervical cancer occur in these less developed regions. Some of the regions in the world with the highest mortality rates include the WHO South-East Asia and Western Pacific regions, followed by India and Africa.
Recent data estimate that 10% of yearly cancers worldwide are caused by viral infections. This number translates into more than a half million lives lost each year to virus-caused malignancies. The bulk of these cancers and resultant deaths are attributable to:
- Human Papillomavirus (HPV): causes 600,000 cancer cases per year
- Hepatitis B Virus (HBV) : 380,000 cancer cases per year
- Hepatitis C Virus: 220,000 cancer cases per year
- Epstein-Barr Virus: 110,000 cancer cases per year.
The ability to nearly eradicate a viral disease with vaccination (eg, polio), is not new. Consequently, the concept of eradicating viral-associated malignancy via vaccination is logical. Vaccinations against HBV have been available for many years and vaccines against some strains of HPV already exist.
Cervical cancer is the most prevalent HPV-related cancer and the fourth most common cancer in women. HPV is the cause of nearly all cervical cancer cases, and HPV genotypes 16 and 18 are responsible for 70% of cervical cancers. In the United States, HPV is responsible for 60% of oropharyngeal cancers, 90% of which are caused by HPV 16.HPV is also the cause of 91% of anal cancers, 75% of vaginal cancers, 69% of vulvar cancers, and 63% of penile cancers, again with HPV 16 as the predominant oncogenic genotype.
HPV vaccines have been available since 2006. Bivalent, quadrivalent, and, more recently, nonavalent (nine-valent) vaccines against HPV genotypes (targeting those most commonly causing cancer globally) are approved in the United States and other countries for primary prevention of HPV infections because of their strong safety record and their ability to prevent new cancer- causing HPV genotype-specific infections and resultant diseases, such as grade 2 and 3 cervical intraepithelial neoplasias (CIN), vaginal, vulvar, and anal intraepithelial neoplasias (as precursor lesions to cancer). Because of the long latency and the prolonged pre-invasive phase after infection with HPV, many years of follow-up are needed for the ongoing trials to demonstrate a significant reduction in HPV-related cancers. Therefore, intermediate outcomes, such as decrease in precancerous lesions (ie, CIN), are considered acceptable surrogate end points for reduced incidence of cervical cancer. Efficacy and safety studies of all three HPV vaccines have had remarkably similar results.
Numerous reports and recommendations that have been issued by national and state-level bodies and organizations and a number of professional medical organizations have issued statements supporting the implementation of this cancer-reducing strategy. Since 1982, more than 1 billion doses of HBV vaccine have been administered worldwide. Cost of the vaccine is an important factor in determining the success of the vaccination.
Despite the almost certainty that cancers caused by oncogenic HPV genotypes will be dramatically reduced, the use of HPV vaccination in the United States is low (36% of girls and boys, respectively, age 11 to 13 years have received all three doses), and use worldwide is variable. According to the report by the Center for Disease Control and Prevention (CDC) in 2012, an estimated 53,000 additional cases of cervical cancer could be prevented by increasing three-dose HPV vaccination coverage to 80%.
1992, the WHO advocated for the HBV vaccine to be considered part of the standard immunization panel in all countries. In 2000, with the support of many, the Global Alliance for Vaccine and Immunization (GAVI Alliance) was created. The primary focus of the GAVI Alliance was on subsidizing new vaccines for low- and lower-middle–income countries to reduce the lag time between the development and the introduction of new childhood vaccines. The GAVI Alliance estimates that 3.7 million deaths resulting from HBV infection have been prevented by vaccine programs created during the years 2000 to 2011.
Although barriers to HPV vaccination are multi-factorial, and few advances have been seen since 2006, the success of vaccination programs seems highly dependent on the support and recommendations of public health officials and health care professionals. When parents and health care providers are asked about the low HPV vaccination rates, the following barriers are identified:
- Limited understanding of HPV and HPV-related diseases.
- Being unaware of or forgetting about the need for additional doses.
- Safety concerns about the vaccine
- Discomfort talking about sexual behavior
- Lack of time for discussions about the vaccine among clinicians
- Lack of a clear recommendation from a health care provider
- Parental belief that son or daughter is too young for the vaccine and/or not sexually active
- Lack of adequate reimbursement and concerns about cost of the vaccination to the patient
Cervical cancer is one of the most common yet most preventable cancers among women living in low and middle income countries, and its incidence, prevalence, and mortality are aggravated by a lack of sustainable cervical cancer screening programs in these countries. It is estimated that more than 70% of cervical cancer diagnoses could be prevented with the current vaccine. Both bivalent and quadrivalent HPV vaccines have been demonstrated to reduce HPV-related infection and incidence of precancerous lesions. Future vaccines may be able to prevent more cases of cervix cancer worldwide. We need to encourage families to vaccinate their young family members.
Portea Medical has been giving HPV vaccinations along with other vaccinations for Influenza, Pneumococcus, Hep. B, Hep. A, Cholera and Typhoid, since the last 18 months. The vaccination program is an important arm of preventive health of the Organisation and so far been administered to over 75,000 people. To avail vaccination at home, click here.