Is radiotherapy needed after adequate local excision of localized DCIS?

Abstract

Despite the fact that mastectomy remains the safest treatment for ductal carcinoma in situ, breast conserving surgery is still a frequent option. Three randomized trials (NSABP B17- EORTC 10853- UK DCIS) have confirmed a statistically significant reduction of LR rate by the addition of a whole breast irradiation at 50 Gy (RT). The rate of LR, both in situ and invasive, has been reduced by 45-55% with RT, e.g. in the NSABP B-17 trial, with a 129-month follow-up, the overall LR rate decreased from 31.7% to 15.7% (p = 0.001). The RT benefit was confirmed in all subgroups of patients, even with a lack of advantage on survival. Two large retrospective studies (in France and California) also confirmed the benefit of RT after lumpectomy, but with small differences in the subgroup with large excision (and margin width > or = 10 mm). On the other hand, invasive LR can give a 15-20% subsequent metastasis rate. Today, the current whole breast RT using megavoltage photons and provisional CT-scan-based dose distribution is resulting in less than 1% of complications. Until now, no studies have clearly identified patients with a sufficiently low LR risk to justify the lack of RT after lumpectomy. Finally, DCIS treatment requires a close multidisciplinary collaboration; moreover surgery and radiotherapy should be used jointly to obtain optimal long-term local control, such as for so many tumors.