Mammographically detected ductal carcinoma in situ treated with conservative surgery with or without radiation therapy - Patterns of failure and 10-year results

Objective The authors reviewed their institution's experience treating mammographical ly detected ductal carcinoma in situ (DCIS) of the breast with breast-conse rving therapy (BCT) to determine 10-year rates of local control and surviva l, patterns of failure, and factors associated with outcome. Summary Background Data From January 1980 to December 1993, 177 breasts in 172 patients were treate d with BCT for mammographically detected DCIS of the breast at William Beau mont Hospital, Royal Oak, Michigan. Methods All patients underwent an excisional biopsy, and 65% were reexcised. Thirty -one breasts (18%) were treated with excision alone, whereas 146 breasts (8 2%) received postoperative radiation therapy (RT). All patients undergoing RT received whole-breast irradiation to a median dose of 50.0 Gy. One hundr ed thirty-six (93%) received a boost to the tumor bed for a median total do se of 60.4 Gy. Median follow-up was 5.9 years for the lumpectomy alone grou p and 7.2 years for the lumpectomy + RT group. Results In the entire population, 15 patients had an ipsilateral breast recurrence. The 5- and 10-year actuarial rates of ipsilateral breast recurrence were 7 .8% and 7.8% for lumpectomy alone and 8.0% and 9.2% for lumpectomy + RT, re spectively. Eleven of the 15 recurrences developed within or immediately ad jacent to the lumpectomy cavity and were designated as true recurrences or marginal misses (TR/MM). Four recurred elsewhere in the breast. Eleven of t he 15 recurrences were invasive, whereas 4 were pure DCIS. Only one patient died of disease, yielding 5- and 10-year actuarial cause-specific survival rates of 100% and 99.2%, respectively. Eleven patients were diagnosed with subsequent contralateral breast cancer, yielding 5- and 10-year actuarial rates of 5.1% and 8.3%, respectively. Clinical, pathologic, and treatment-r elated factors were analyzed for an association with ipsilateral breast fai lure or TR/MM. No factors were significantly associated with ipsilateral br east failure. In the entire population, the omission of RT and younger age at diagnosis were significantly associated with TR/MM. Patients younger tha n 45 years at diagnosis had a significantly higher rate of TR/MM in both th e lumpectomy + RT and lumpectomy alone groups. None of the 37 patients who received a postexcisional mammogram had an ipsilateral breast failure versu s 15 in the patients who did not receive a postexcisional mammogram. Conclusions Patients diagnosed with mammographically detected DCIS of the breast appear to have excellent 10-year rates of local control and overall survival when treated with BOT. These results suggest that the use of RT reduces the ris k of local recurrence and that patients diagnosed at a younger age have a h igher rate of local recurrence with or without the use of postoperative RT.