Association Between Human Papillomavirus and Thymic Cancer: A Population-Based Cohort Study.

Background: Thymic carcinoma is an uncommon malignancy with unclear etiology. Although human papillomavirus (HPV) has been implicated in multiple cancers, its potential association with thymic cancer remains poorly studied in large population-based cohorts. This study aimed to investigate the role of HPV in developing thymic cancer and the risk of different HPV genotypes on thymic cancer. Methods: We examined the longitudinal relationship between HPV infection and thymic cancer in a cohort of 10,558 women aged 30 to 65 years who were enrolled in 1991 or 1992 in Taiwan. Cervical cells collected at the beginning of this study were tested for 39 types of HPV. The incidence of newly developed thymic cancer was determined through a computerized linkage with the National Cancer Registry by using the topography code 164 for thymic cancer in the International Classification of Diseases, Ninth Edition. Results: An increased risk of thymic cancer was associated with HPV infection, with an HR (95% CI) of 2.42 (0.62 to 9.38) after adjustment for age and body mass index. The level of risk was higher for infections with HPV types classified in the International Agency for Research on Cancer group 3, with an adjusted HR (95% CI) of 11.82 (2.51 to 55.70). Conclusion: This population-based cohort study provides longitudinal evidence that HPV infection may be associated with an increased risk of thymic cancer. While no significant overall association was observed, subgroup analysis revealed a notable association with HPV genotypes classified as IARC group 3. Additional studies are necessary to confirm the role of HPV in thymic carcinogenesis.