Clinical Features of Breast Cancer Patients with Human T-Cell Lymphotropic Virus Type-1 Infection

Background: Human T-cell lymphotropic virus type 1 (HTLV-1) is a retrovirus that causes adult T-cellleukemia/lymphoma (ATL), an aggressive form of T-cell malignancy. The relationship between HTLV-1 infection andcancer progression is controversial. HTLV-1 encodes oncogenic protein TAX1 and it is hypothesized that HTLV-1infection is associated with breast cancer progression. In this study, we evaluated the relationship between HTLV-1infection and clinicopathological factors in breast cancer patients. Methods: We retrospectively analyzed 610 patientswith primary breast cancer who underwent surgical treatment without preoperative chemotherapy at KagoshimaUniversity Hospital between January 2001 and January 2015. Results: When patients with and without HTLV-1 infectionwere compared, no differences in clinicopathological factors were observed, except for age. Disease-free survival andoverall survival rates did not differ between groups. Conclusions: HTLV-1–positive patients were significantly olderthan HTLV-1–negative patients. It was supposed to be due to the fact that the HTLV-1 infection rate is decreasing. Anyeffect of HTLV-1 infection on breast cancer progression appears to be negligibly small.