Radiotherapy in breast-conserving treatment for ductal carcinoma in situ: first results of the EORTC randomised phase III trial 10853

Background Ductal carcinoma in situ (DCIS) of the breast is a disorder that has become more common since it may manifest as microcalcifications that c an be detected by screening mammography. Since selected women with invasive cancer can be treated safely with breast-conservation therapy it is parado xical that total mastectomy has remained the standard treatment for DCIS. W e did a randomised phase III clinical trial to investigate the role of radi otherapy after complete local excision of DCIS. Methods Between 1986 and 1996, women with clinically or mammographically de tected DCIS measuring less than or equal to 5 cm were treated by complete l ocal excision of the lesion and then randomly assigned to either no further treatment (n=503) or to radiotherapy (n=507; 50 Gy in 5 weeks to the whole breast). The median duration of follow-up was 4.25 years (maximum 12.0 yea rs). All analyses were by intention to treat. Findings 500 patients were followed up in the no further treatment group an d 502 in the radiotherapy group. In the no further treatment group 83 women had local recurrence (44 recurrences of DCIS, and 40 invasive breast cance r). In the radiotherapy group 53 women had local recurrences (29 recurrence s of DCIS, and 24 invasive breast cancer). The or year local relapse-free w as 84% in the group treated with local excision alone compared with 91% in the women treated by local excision plus radiotherapy (log rank p=0.005; ha zard ratio 0.62). Similar reductions in the risk of invasive (40%, p=0.04) and non-invasive (35%, p=0.06) local recurrence were seen. Conclusions Radiotherapy after local excision for DCIS, as compared with lo cal excision alone, reduced the overall number of both invasive and non-inv asive recurrences in the ipsilateral breast at a median follow-up of 4.25 y ears.