Prise en charge des carcinomes mammaires in situ : surtraitement ? Peut-on faire moins ?

Ductal carcinoma in situ represents now approximately 15% of all breast cancers. Ductal carcinoma in situ is the first step of breast cancer development and evolves in a majority of the cases to invasive breast cancer, but with various delays and aggressiveness. Due to extension and/or multicentricity, mastectomy is still necessary in 30% of the cases. Even in very selected cases (low grade, small size, free margins), breast-conserving surgery alone gives a 15 to 20% long-term local recurrence rate, half of them invasive. These invasive local recurrences can give a 12 to 15% long-term metastasis rate. Radiotherapy after breast conserving surgery halves the local recurrence risk, as demonstrated by four randomized trials and two meta-analyses. The local recurrence risk factors are clinical, histopathological and/or treatment-related. In order to avoid “overtreatment”, several studies now try to select lesions with very low local recurrence risk, integrating some molecular parameters. However, we must be cautious to avoid “undertreatment” for an almost completely curable disease with an optimal treatment at the beginning.