The University of Pittsburgh was one of the founding institutions of the Primary Breast Cancer Therapy Group (NSABP) in 1958 and has continued as a major participant. Patients (593) have been entered into protocols evaluating the relative efficacy of radical and total mastectomy with and without post operative radiation, segmental mastectomy and a variety of protocols employing chemotherapy in various combinations alone or with the anti-estrogen tamoxifen or C. parvum. Since all patients had Stage I or II breast cancer and received prolonged adjuvant therapy, intensive follow-up continues to be involved. At the present time, 425 patients are still receiving treatment and/or being followed. In addition to entering patients into protocols and providing the NSABP Biostatistical Unit with high quality data, this institution has provided large numbers of patients and specimens for serum hormonal assays, chromosomal abnormalities and L-PAM absorption studies. The present application seeks funding to a) continue follow-up on patients in closed protocols, b) permit and increase patient accrual in on-going protocols, c) submit timely and complete data to the Biostatistical Unit, d) collect appropriate biological material and information relevant to the protocols and e) participate in all activities of the NSABP. This proposal provides the single most important mechanism for promoting the multidisciplinary treatment of cancer via clinical trials in this environment.