A variety of cancer sites and exposures have been explored, with many investigations involving multidisciplinary approaches to understanding biologic mechanisms. Etiologic research on breast cancer has been a major emphasis, with studies showing increased risks of in situ cancers with hormone replacement therapy and of early onset disease with oral contraceptive usage. The role of endogenous hormones in the etiology of breast and other female cancers continues to be of major interest, with methodologic studies having been undertaken in preparation for full-scale analytic studies. Also explored with respect to breast cancer have been effects of breastfeeding and occupational exposures, and reasons for the geographic variation in mortality in the U.S. Studies on the role of the human papillomaviruses (HPV) have shown that it is the major etiologic agent for cervical cancer worldwide. Several large prospective studies are assessing the relationship of HPV presence and persistence to subsequent disease risk. In preliminary data, newly developed serologic tests appear to be useful predictors of female genital disease risk. Also of interest with respect to female health are the long-term effects of in utero exposure to diethylstilbestrol, silicone breast implants, and ovulation-stimulating drugs, with three separate cohort studies underway to assess a variety of disease outcomes. Environmental exposures of notable interest include pesticides and water chlorination byproducts, with one case-control study showing increased risks in certain subgroups (notably smokers) of rectal and bladder cancers associated with long-term consumption of chlorinated surface water. Further, the occurrence of cancer among twins and among several occupationally exposed cohorts have been examined. Finally, descriptive approaches have been utilized to derive clues as to future directions for etiologic research, with investigations undertaken of the risk of second malignancies following rare female genital cancers, of the seasonal variation in melanoma detection, and of time trends in lymphoma.
