Effects of patient selection on the applicability of results from a randomised clinical trial (EORTC 10853) investigating breast-conserving therapy for DCIS
In EORTC trial 10853, patients with histologically confirmed surgical clearance of ductal carcinoma in situ (DCIS) are being randomised to observation alone or to receive external radiation to the breast (50 Gy). So far, 190 patients have been entered from 27 centres. An analysis has been conducted of patients with DCIS presenting to 6 of the participating hospitals. Within these centres there was a total of 216 patients with biopsy confirmed DCIS, without invasion, between 1985 and 1989. However only 77 (36%) were entered into the trial. The major reason for non-entry was that DCIS was too extensive (76/139, 55%), so that in situ disease extended to the margins of excision. Other reasons for exclusion included prior breast cancer (18%), delay in histological diagnosis (6%) and a lump measuring more than 3 cm in diameter (4%). Only 6 patients (4%) refused to take part in the trial. Thus the eventual results of the trial may be applicable only to a minority of patients with DCIS.