Age-specific occurrence of HPV16- and HPV18-related cervical cancer.

The age-specific occurrence of cervical cancer related to human papillomavirus (HPV) genotypes HPV16 and HPV18, the two targeted by current HPV vaccines, is not well described. We therefore used data from two large, tissue-based HPV genotyping studies of cervical cancer, one conducted in New Mexico (n = 744) and an International study restricted to cancers (n = 1,729) from Europe, North America, and Australia to represent those regions with widely available cervical cancer screening facilities. HPV results were categorized as HPV16- or HPV18-positive (HPV16/18) versus other HPV genotype. We observed a decreasing proportion of HPV16/18-positive cancers with increasing age in the International study (Ptrend < 0.001) and New Mexico study (Ptrend < 0.001). There was no heterogeneity in the relationship between age of diagnosis and the proportion of HPV16/18-positive cancers between studies (P = 0.8). Combining results from the two studies (n = 2,473), the percentages of HPV16/18-positive cases were 77.0% [95% confidence interval (CI): 75.1%-78.9%] for women less than 65 years old and 62.7% [95% confidence interval (CI): 58.4%-66.9%] for women aged 65 and older (P < 0.001). In women who are under the age of 25 and have been vaccinated before becoming sexually active, the cervical cancer incidence is expected to be approximately 3.5 per million by 2020. HPV vaccination against HPV16/18 may have a greater impact on cervical cancers in women under 65 than in women aged 65 and older. These data will inform the age-specific impact of HPV vaccination and its integration with cervical cancer screening activities.