Background: We analyzed data from a population-based, multi-center, case-control study to determine whether the occurrence of histologic types of uterine sarcoma is related to exogenous hormone use and/or to two correlates of endogenous estrogens: excess weight and cigarette smoking.
Methods: One hundred sixty-seven women with newly-diagnosed uterine sarcoma (56 leiomyosarcoma, 85 mixed mullerian tumors, and 26 endometrial stromal sarcomas) were interviewed by telephone regarding possible risk factors for these neoplasms, For comparison, 208 women identified at random from the general population of the study areas were interviewed as controls.
Results: Use of oral contraceptives was positively associated with the risk of leiomyosarcoma (odds ratios [OR] = 1.7, 95% confidence interval [CI] = 0.7, 4.1), primarily among women who last used these medications 15 or more years prior to diagnosis. Use of noncontraceptive estrogens was directly associated with the risk of mixed mullerian tumors, but only among recent and long-term users of these medications. Women in the highest quantile of body mass index (> or = 27.5 kg/m2) one year prior to diagnosis were at increased risk of each type of uterine sarcoma (leiomyosarcoma, OR = 2.5, 95% CI = 1.1, 5.7; mixed mullerian tumors, OR = 2.9, 95% CI = 1.3, 6.7; stromal sarcoma, OR = 3.5, 95% CI = 1.1, 10.9). Women who had ever smoked cigarettes were at reduced risk of leiomyosarcoma (OR = 0.6, 95% CI = 0.3, 1.1) and stromal sarcoma (OR = 0.5, 95% CI = 0.2, 1.2), but the relationship was not more pronounced among heavy smokers; no association with smoking was observed with mixed mullerian tumors.
Conclusions: Several of these findings parallel those from studies of endometrial carcinoma and may indicate a role for unopposed estrogen in the etiology of histologic types of uterine sarcoma.