Human T-cell leukemia virus type І associated with an increased risk of primary malignant neoplasm

The correlation between human T-cell leukemia virus type І (HTLV-І) infection and malignant neoplasms other than adult T-cell lymphoma (ATL) remains unknown. We analyzed the frequency of primary malignant neoplasm in HTLV-І-seropositive patients. From January 2006 to December 2016, 203 patients were diagnosed as HTLV-І-seropositive at Kansai Medical University Hospital. Among them, 32 developed a primary malignant neoplasm. Their median age was 64 years old, 63% of them were male, and 69% of them were HTLV-I carriers. This group had the following distribution of ATL subtypes: 31% smoldering type, 0% chronic type, 3% acute type, and 3% lymphoma type. Among them, 53% was hematology malignancy, and solid tumor was 47%. The most frequent type of hematological malignancy was T-cell lymphoma (23%), followed B-cell lymphoma (16%), and myelodysplastic syndromes (6%). The most frequent primary solid tumor locations were the lung (15%), followed by the colon (9%), prostate (6%), kidney (6%), cervix (2%), breast (2%), liver (2%), pancreas (2%), and oral cavity (2%). Our results suggest that HTLV-Іinfection is often associated with the development of other malignant neoplasms. Therefore, HTLV-І-positive patients should be made aware of their increased risk for the onset of a malignant neoplasm and undergo increased surveillance.