No Cervical Cancer Cases Following HPV Vaccination in Scotland
HPV infection is a major cause of cervical cancer – the fourth most common cancer in women worldwide.
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No cervical cancer cases have been observed in fully vaccinated women who received the human papillomavirus (HPV) vaccine at age 12 or 13 in Scotland since the program began in 2008, according to a new study.
Introduction of the HPV vaccine
HPV infection is a major cause of cervical cancer – the fourth most common cancer in women worldwide. Approximately 99.7% of cervical cancers are caused by infection with so-called “high-risk” types of HPV.
High-risk vs low-risk HPV
There are over 100 types of HPV, but some are associated with higher risks of developing cervical cancers than others. For example, HPV 16 and 18 carry the highest risk and are responsible for around 70% of cervical cancers, while types 6, 11, 42, 43 and 44 are considered low-risk.
HPV spreads through sexual contact, though most people never develop symptoms and are unaware that they are infected. The first HPV vaccine approved by the FDA in 2006 has proven extremely effective at providing immunity against the types of HPV most commonly associated with cervical cancer.
To be most effective, the CDC recommends that the vaccine should be administered at 11–12 years of age, but teenagers and young adults up to age 26 can also receive the HPV vaccine. Only 2 doses are needed if the first was given before their 15th birthday, while those who start the immunization program aged 15–26 require a third dose.
In the current study, researchers from Public Health Scotland – where the HPV vaccine program began in 2008 – investigated how factors such as age at vaccination and socioeconomic deprivation influenced cervical cancer incidence. The research is published in the Journal of the National Cancer Institute.
The bivalent vaccine prevents invasive cervical cancer
Individuals included in the study received the bivalent vaccine, which protects against HPV 16 and 18, as well as providing some cross-protection for 3 other types of HPV. Today, the vaccination program uses a nonavalent vaccine that protects against nine types of HPV.
The analysis, led by Dr. Tim Palmer, found no recorded cases of invasive cancers in those vaccinated at 12–13 years of age during the period studied. This was true regardless of the number of doses they received.
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Subscribe for FREEThe age of immunization also had a significant impact on the efficacy of the vaccine; for those vaccinated at 14–18 years of age, three doses were required for the vaccine’s efficacy to be statistically significant.
“The degree of benefit related to the age at vaccination – the younger (age 14–16 years) benefitted more than those receiving the vaccine at age 17–18 years,” said Palmer, the lead author of the study and an honorary senior lecturer at the University of Edinburgh, speaking to Technology Networks. “The vaccine effectiveness was 100% for immunization at age 12–13, 86% for immunization at age 14–16 and 39% for immunization at age 17–18.”
“No benefit was seen in women vaccinated over the age of 18,” he added.
Palmer and colleagues found that those from more deprived areas benefitted more from vaccination than those from less deprived areas. Deprivation was measured by taking into account factors such as housing quality, employment levels, education and availability of services such as the health service.
“Historically, women in the deprived areas have had higher rates of cervical pre-cancer and cancer. One of the risk factors for this is that women in these areas are less likely to attend screening,” explains Palmer. “They are also less likely to be vaccinated but, despite this, vaccination benefits them more.”
Deprivation was measured using data on factors such as housing quality, employment levels, education and the availability of services such as the health service.
The importance of screening and vaccination
“These findings emphasize the tremendous benefit of HPV vaccination before becoming sexually active,” Palmer explained. “In the UK, with its established school immunization program, it is very easy to be vaccinated at the appropriate age (age 11–12 years). Maintaining a high uptake of the vaccine is the best way to eliminate cervical cancer as a major problem for women.”
Palmer also recommends that fully immunized people continue to attend cervical screening, as the vaccine does not protect against all cancer-causing HPV types. Nevertheless, together with cervical screening, the vaccine’s efficacy has the potential to ensure that cervical cancer is no longer a major problem.
“The findings should be the final nail in the coffin of serious anti-vaccine arguments,” Palmer concluded.
Reference: Palmer TJ, Kavanagh K, Cuschieri K, et al. Invasive cervical cancer incidence following bivalent human papillomavirus vaccination: a population-based observational study of age at immunization, dose, and deprivation. JNCI. 2024:djad263. doi: 10.1093/jnci/djad263
Dr. Tim Palmer was speaking to Dr. Sarah Whelan, Science Writer for Technology Networks.
About the interviewee:
Dr. Tim Palmer is the Scottish clinical lead for cervical screening and is responsible for directing the development of cervical cytology services in Scotland. He also holds the position of honorary senior lecturer in the University of Edinburgh’s Division of Pathology and is involved in HPV research, with a focus on the development of cervical screening services.
