Time trend and Age-Period-Cohort analysis of potentially HPV-related oral and pharyngeal cancer incidence in Singapore between 1968 and 2017

•The incidence of HPV-related oral and pharyngeal cancer seems stable between 1968 and 2017 which is not the case in much of the world.•The incidence of HPV-unrelated oral and pharyngeal cancers declined between 1968 and 2017 which is the case in much of the Western world.•Young cohorts had the lowest incidence of HPV-related cancers. HPV-related cancers increased from 1988 to 1997. To examine trends and age-period-cohort effects (APC) on oral and pharyngeal cancers incidence in Singapore between 1968 and 2017 by human papillomavirus (HPV) status. All diagnosed oral and pharyngeal cancers and population size were extracted from the Singapore Cancer Registry and the Department of Statistics Singapore, respectively. Anatomical subsites were used as a proxy for HPV infection. Prais-Winsten regression assessed trends of age-standardised incidence rate (ASIR) (per 100,000 person-years); Poisson regression assessed APC effects on HPV-related and HPV-unrelated cancers. Over 50 years, 1,618 HPV-related and 2,977 HPV-unrelated oral and pharyngeal cancers were diagnosed, with the highest ASIR in Indians (6.93), followed by Chinese (2.81), and Malays (1.81). Overall, ASIR HPV-related cancers were stable while HPV-unrelated cancers decreased. The male–female ASIR ratio reduced from 5.82 (1968–1977) to 4.0 (2008–2017) for HPV-related cancers, and from 2.58 (1968–1977) to 1.52 (2008–2017) for HPV-unrelated cancers. HPV-unrelated ASIR in males decreased, but in females only among Indians. HPV-related ASIR decreased only among Indian females. The cohort born between 1983 and 1992 had the lowest incidence of HPV-related cancers in males but the highest in HPV-unrelated cancers. Period effect mainly contributed to HPV-related cancer among males with increased incidence after 1997. Overall, the age effect was more pronounced in males. HPV-related cancers accounted for 1/3 of oral and pharyngeal cancers. A significant decline was observed only for HPV-unrelated cancers. The cohort effect was mainly attributed to HPV-unrelated cancer incidence, while the period effect largely contributed to HPV-related cancer incidence, but only among males.