Relationship among Strongyloides stercoralis Infection, Human T-Cell Lymphotropic Virus Type 1 Infection, and Cancer: A 24-Year Cohort Inpatient Study in Okinawa, Japan

This study evaluated the prevalence of Strongyloides stercoralis infection and human T-cell lymphotropic virus type 1 (HTLV-1) infection in the population. In addition, this study investigated the relationship between S. stercoralis infection or HTLV-1 infection and a patient's risk of developing related cancers. This is a retrospective cohort study of 5,209 patients. The prevalence of S. stercoralis infection was 5.2% among all patients. The prevalence among men (6.3%) was significantly higher than among women (3.6%, P < 0.001). The prevalence of HTLV-1 infection among this population was 13.6% and the prevalence among women (15.5%) was significantly higher than that of men (12.3%, P < 0.001). HTLV-1 seroprevalence was higher in patients with liver cancer (P = 0.003, odds ratio [OR]: 1.91, 95% confidence interval [CI]: 1.24, 2.95) and in those with lymphoma other than adult T-cell leukemia/lymphoma (ATLL) (P = 0.005, adjusted OR: 2.76, 95% CI: 1.36, 5.62) if compared with patients without any neoplasm. The prevalence of both S. stercoralis and HTLV-1 in the Okinawan population has been steadily decreasing over the past 24 years. HTLV-1 infection significantly increases the odds of developing liver cancer and lymphomas other than ATLL.