Risk of bronchioloalveolar carcinoma in patients with human T-cell lymphotropic virus type 1 (HTLV-I): Case-control study results

Background: Human T-cell lymphotropic virus type 1 (HTLV-I) causes not only adult T-cell leukemia (ATL) but also HTLV-I associated T-cell bronchioloalveolitis, which is often chronic and subclinical. We have experienced eight HTVL-I carriers with bronchioloalveolar carcinoma, which is known to arise from bronchioloalveolar pneumocytes. This case-control study clarified the risk of bronchioloalveolar carcinoma in HTLV-I carriers. Materials and Methods: During the past four years, 212 lung cancer patients were examined for serum anti-HTLV-I antibody. They underwent surgical treatment for lung cancer at Kumamoto University Hospital. Of these, 8 (4%) were HTLV-I carriers. As controls for this case-control study, we selected 24 HTLV-I negative-lung cancer patients (1:3 case-control ratio) matched for sex, age, and smoking status. The distributions of histological types of lung cancer were compared between the case (HTLV-I positive) and control (HTLV-I negative) groups. Results: Histological types of the 8 HTLV-I carriers were bronchioloalveolar carcinoma in 6 patients and adenocarcinoma with bronchioloalveolar carcinoma component in 2. The prevalence of bronchioloalveolar carcinoma in HTLV-I carriers, 6 of 8 (75%), was significantly higher than the 6 of 24 (25%) in HTLV-I negative patients (p=0.02). The prevalence of bronchioloalveolar carcinoma or adenocarcinoma with bronchioloalveolar carcinoma component in HTLV-I carriers, 8 of 8 (100%), was also significantly higher than the 13 of 24 (54%) in HTLV-I negative patients (p=0.02). Conclusion: HTLV-I might be one risk of bronchioloalveolar carcinoma, probably because of inflammatory and/or immunologic responses involving bronchioloalveolar pneumocytes.