Did TCDD exposure or service in Southeast Asia increase the risk of cancer in air force Vietnam veterans who did not spray agent orange?

Objective: We sought to examine cancer incidence in 1482 Air Force veterans who served in Southeast Asia (SEA) and who were not occupationally exposed to herbicides. Methods: Cancer incidence between 1982 and 2003 was determined by record review and Cox proportional hazards models were used to estimate risk ratios across serum 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and years served in SEA categories. Results: All sites cancer risk increased with TCDD (relative risk = 1.6, 95% confidence interval = 1.2-2.2). The risk of prostate cancer increased with years of SEA service but not with TCDD. TCDD and years of SEA service interacted with all sites cancer; the risk was greatest in those with the highest TCDD levels and the longest time served in SEA. Conclusions: These results suggest nonoccupational exposures to TCDD or other factors while in SEA may contribute to cancer risk in these veterans.