Background: The burden of HPV-related cancers in different regions worldwide varies according to several factors. This study aims to measure inequality in the risk of incidence of HPV-related cancers in term of geographical risk patterns in northern Thailand using a population-based cancer registry data.
Methods: Trends in age-standardized HPV-related cancer incidence were calculated for the 2008-2017 time period. The Besag-York-Molli´e model was used to explore the spatial distribution of the relative risk (RR) of HPV-related cancers at the district level. A higher RR reflects a larger disparity. The geographical risk pattern of the diseases in two periods, 2008-2012 and 2013-2017 were described and compared.
Results: From 2008 to 2017, the incidence of oropharyngeal and anal cancers showed a slightly increased trend in males but remained stable in females, the incidence of vulvar, vaginal and penile cancers were stable while the incidence of cervical cancer decreased. The RR range was closer to 1 in the second period compared to the first period. This suggests a decrease in the disparities of incidence of cervical cancer. However, in some areas near the Thai-Myanmar border, the RR values remained high.
Conclusion: The incidence rate of most HPV-related cancers remained low and stable over the study period in northern Thailand. For the most common HPV-related malignancy, cervical cancer, the incidence rate steadily decreased but with marked geographic disparities, possibly reflecting health inequity especially in the border areas.