Young women who received the human papillomavirus (HPV) vaccine through a school-based program had fewer cervical cell anomalies when screened for cervical cancer, according to a new study in CMAJ (Canadian Medical Association Journal).
"Eight years after a school-based HPV vaccination program was initiated in Alberta, 3-dose HPV vaccination has demonstrated early benefits, particularly against high-grade cervical abnormalities, which are more likely to progress to cervical cancer," writes Dr. Huiming Yang, Medical Officer of Health and Medical Director, Screening Programs, Alberta Health Services, Calgary, Alberta, with coauthors.
In 2008, the province introduced HPV vaccination for Grade 5 girls (aged 10-11) and a 3-year catch-up program for Grade 9 girls (aged 14-15); in 2014, it was expanded to include boys. The program provides 3 doses of the vaccine that protects against two strains of HPV, which account for 70% of all cases of cervical cancer.
To determine whether the vaccination had an impact on Papanicolaou (Pap) test results, Alberta researchers looked at data on the first group of women who participated in both the school vaccination program and cervical cancer screening.
A total of 1,481 women (14.5%) had cervical anomalies detected during screening. The remaining 8,723 (85.5%) women had no cervical abnormalities detected. Among those with abnormalities, most (1,384 or 93.5%) had low-grade cervical abnormalities, and the remaining 97 (6.5%) had high-grade abnormalities.
More than half of the study participants (56%) were unvaccinated, and 44% had received 1 or more doses of the HPV vaccine before being screened for cervical cancer. Of the women who had been vaccinated, 84% received 3 or more doses. Among the unvaccinated women, 16.1% had cervical abnormalities, compared with 11.8% in the fully vaccinated group.
The authors note that effective HPV vaccination with broad uptake will affect the harms and benefits of cervical screening.
"With population-based HPV vaccination, guidelines for cervical cancer screening may need to include a later age for screening initiation age and/or a longer interval between screenings," they write.
The authors hope that their findings and future research will lead to improved primary and secondary prevention efforts, with integration of HPV vaccination and cervical cancer screening programs.
July 5, 2016
Credit: Canadian Medical Association Journal