Soft-tissue sarcoma and dioxin: A case-control study.

Soft-tissue sarcoma has been proposed to be a candidate for a dioxin-induced cancer. However, previous epidemiologic studies have suffered from poor exposure data and mixed exposures. We studied the association between sarcoma risk and individually estimated dioxin exposure in a general population exposed to relatively low levels of dioxin via food. A multicenter prospective case-control study was conducted in 4 university hospitals and 12 other hospitals in southern Finland. Participants included 110 patients with soft-tissue sarcoma (cases) and 227 area- and age-matched controls. Controls were patients operated for appendicitis. Individual dioxin concentrations were analyzed from subcutaneous fat samples by gas chromatography-mass spectrometry. The average (range) dioxin concentration was 33.4 (4.4-145.5) ng/kg (toxic equivalencies in fat according to WHO). No increased risk associated with increased dioxin concentration was observed. In contrast, the highest risk of sarcoma was found at low levels of dioxin. Odds ratios for different quintiles as compared with the lowest quintile of dioxins (median, 11.5 ng/kg) varied from 0.43 (95% CI = 0.18-1.05) to 0.65 (95% CI = 0.22-1.95). The result was little affected by studied confounders and the findings were similar for different sarcoma subtypes, age groups and study areas. The results imply that dioxin does not increase the risk of soft-tissue sarcoma at the present population levels.