THERAPEUTIC AND DIAGNOSTIC FACTORS AS RELATED TO CANCER RISK

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A major emphasis of this program of research has been to define the relationship of exogenous hormones to subsequent cancer risk. Previous research has demonstrated an increased risk of incident breast cancer following usage of menopausal estrogens. However, women who use replacement estrogens at the time of diagnosis of a breast cancer appear to experience reductions in breast cancer mortality. An analysis within the context of a large screening program showed that this was not due to earlier detection of tumors among hormone users. Analyses of hormone replacement therapy within both the screening program and a record linkage study in Sweden showed that the combined estrogen-progestin regimen increased risk beyond that associated with estrogens alone. In the screening study, increases in risk were evident for both early and late- stage disease and were greater for progesterone receptor- positive than negative tumors. Relationships of hormone use with other cancers (including endometrial and lung) are also being explored. Effects of oral contraceptives on cancer risk have also been pursued in several investigations. In a study of cervical adenocarcinomas, use of oral contraceptives appeared to increase the risk of in situ tumors. Also underway is a retrospective cohort study to evaluate cancer risk following different types of infertility and exposure to ovulation- stimulating drugs. In a comparison study in Denmark, cancer risks among children conceived following use of these drugs is being pursued. Also under analysis are data from a recently completed retrospective cohort study of women who received augmentation mammoplasties. A recent review of the literature indicated concern about possible relationships with breast cancer, sarcomas, and several hematopoietic malignancies, including multiple myeloma. For breast cancer, there are concerns regarding effects on both incidence as well as prognosis, since breast implants have been shown to interfere with the ability to mammographically visualize lesions. A study of women who experienced breast reduction operations has also been completed. Analyses are currently underway to examine whether the amount of tissue removed during the operation relates to subsequent reductions in breast cancer risk. Finally, efforts are being made to assess risk of several cancers in relation to different types of gynecologic operations. Of interest are not only operations involving ovarian ablation but also those with more subtle effects, such as tubal ligation. Although this procedure has been linked with substantial decreases in the risk of ovarian cancers, its effects on other tumors (e.g., breast) are less well known. Preliminary analyses within the context of a population-based case-control study do not confirm an etiologic role for the procedure in breast cancer. Human Subjects & Human Subjects: Interview, Questionaires, or Surveys Only