Although approximately 2 million women in this country have undergone augmentation mammoplasty, little is known about long-term effects. There has been concern for some time regarding possible effects of implanted material on the immune system. In addition, there has been a long-standing concern that breast implants may deter the detection of breast cancers. More recently, concern has developed over the possible carcinogenicity of the material used in implants themselves. Of particular concern is the recognition that a polyurethane foam coating used to contain silicone gel in some implants is comprised of the chemicaI 2, 4-diamino toluene, or TDA, which has been linked to increased risks of breast as well as other cancers in rats and mice. To address these concerns, a retrospective cohort study of approximately 12,000 breast implant patients is proposed. It is anticipated that these women will be recruited from a number of large reconstructive and plastic surgery practices in several diverse areas. The cohort will be constructed in such a manner that a variety of different implant types are represented and an average of 10 years of follow-up on the patients is achieved. Records at the collaborating practices will be reviewed to obtain identifiers of potential study subjects, particulars of the surgery and possible co-variates for subsequent diseases. Using a variety of sources, the subjects were traced for current vital status and residence. A questionnaire will be developed and sent to the study subjects. This questionnaire will request information from the subjects on perceived complications of the implant, history of breast examinations and mammograms, frequency of breast self examinations, development of diseases subsequent to the operation (with particular interest on cancer and connective tissue disorders), and potential risk factors for the diseases of interest (e.g., age at menarche, age at first birth, age and type of menopause, family medical history, immune alterations). Because of difficulties in comparing this population to an external standard, an internal comparison cohort was also assembled. This will consist of approximately 4,000 women receiving operations from the same plastic surgery practices as the breast augmentation patients. This comparison group will consist of women undergoing a variety of cosmetic plastic surgery procedures, such as rhinoplasty. Attempts will be made to assemble a cohort with similar ages and operations dates as the breast implant patients. Records of these patients will be abstracted and follow-up pursued in the same manner as for the mammoplasty patients. The cancer incidence and mortality experience of the augmentation mammoplasty patients was compared to both general population rates (using SEER cancer incidence and U.S. mortality rates) and to that of the experience of the other plastic surgery patients. Analyses of the risk of connective tissue disorders focused solely on the internal comparisons, given the absence of available population incidence rates for these disorders. Analyses included efforts to assess risks by various implant characteristics, including age at, calendar time of, and interval since implantation. Internal analyses enabled adjustment for recognized risk factors, particularly for the cancers of interest.