[Initial results of the Project of the German Breast Cancer Study Group on "Breast saving therapy of the small breast cancer"].

In the German Breast Cancer Study Group (GBSG) multicenter trial "Breast preservation in small breast cancer" 1119 patients were accrued over a period of six years. The study was originally designed as a randomized trial which had to be changed into a prospective observation study. A high therapeutic standard was guaranteed by quality control. The univariate analysis of prognostic variables was the first step to a valid treatment comparison. Those factors determined as being significant were combined with the treatment effects in a multivariate analysis. The published results were obtained after a median observation time of four years.