Trends in age-standardized incidence rates of cancers of HPV-related cancer sites in Osaka, Japan: 1977–2019

The trends in cancers of Human papillomavirus (HPV)-related cancer sites in Japan are insufficiently reported. We evaluated the long-term trends of them as a baseline before the effects of HPV vaccine introduction became apparent in Japan. This retrospective, population-based study used data from the Osaka Cancer Registry to analyze 39,349 cases between 1977 and 2019. For women, the ASIRs were particularly high for cervical cancer. For squamous cell carcinoma, the ASIR changed from a decrease (from high to low) to an increase (from low to high) around 2000, although the trend for females aged 40-59 has recently showed no significant change. The trend in ASIR for adenocarcinoma also shifted from an increase to no significant change in the 40-59 age group, but increased consistently in the ≤ 39 age group. Vaginal cancer exhibited no significant change, while cancers of the oropharynx, anus, and vulva have increased. For men, cancers of the oropharynx and anus consistently increased. Squamous cell carcinoma of the anus decreased from 1997 to 2004, but then increased thereafter. Similarly, penile cancer decreased from 1977 to 1995, but then increased. Future studies will observe how this trend changes as groups with high HPV vaccination rates reach cancer-susceptible ages.