Long-Term Follow-Up of Patients in Four Prospective Studies of the German Breast Cancer Study Group (GBSG): A Summary of Key Results

Abstract

Evaluation of treatment modalities and prognostic factors in early breast cancer requires a long-term follow-up of patients in prospective studies. The German Breast Cancer Study Group (GBSG) started four nationwide studies in 1983 in which a total of 2,746 patients have been enrolled and followed for about 10 years. Questions that have been addressed in these studies are still relevant today and comprise the role of breast-conserving therapy, the duration of adjuvant chemotherapy, and whether adjuvant radiotherapy is needed. The key results of these studies are highlighted including some important findings on prognosis, e.g., the role of isolated locoregional recurrence and the prognosis of patients with 10 or more positive lymph nodes. The data of all randomized patients were regularly included into the overviews of the Early Breast Cancer Trialists’ Collaborative Group; the data of the nonrandomized patients have been used to examine the external validity of treatment comparisons. Overall, it can be concluded that the GBSG studies have made valuable and internationally recognized contributions to the prognosis and treatment of patients with early breast cancer.

Multi-state model for studying an intermediate event using time-dependent covariates: application to breast cancer

“…2746 patients from 118 clinical institutions entered the studies. The treatment design of the studies is shown in [5], Table 1. The following covariates were registered at primary diagnosis: patient’s age, menopausal status, number of positive axillary lymph nodes, tumour location, tumour size, histologic tumour grade, oestrogen, and progesterone receptor status.…”

“…The methods are applied to a dataset containing data from four studies conducted by the German Breast Cancer Study Group (GBSG) see e.g. [5]. …”