A mastectomy is a preferred treatment if either of the following conditions applies: There are two or more areas in the breast with DCIS greater than 5cm apart (called “multicentric”), or there are diffuse, malignant-appearing microcalcifications in the breast.
There are persistent positive margins after surgical lumpectomy was done in an attempt to remove all of the DCIS.
Even when these conditions are not present, there are some women for whom the risk/benefit ratio of breast conservation must be carefully assessed and consideration given to mastectomy as a treatment alternative. Neither size nor histology of DCIS is an absolute indication for mastectomy. A relative indication for mastectomy is the presence of extensive DCIS; this usually refers to an area several centimeters in diameter or encompassing an entire quarter of the breast that can be removed with only a small negative margin.
Mastectomy is particularly appropriate for women with small breasts in which an adequate resection would result in a significant deformity. Studies indicate that 1 to 2% of patients treated with mastectomy will have a recurrence of DCIS or invasive cancer, either in the same area or elsewhere in the chest wall. Although mastectomy results in cure rates approaching 100%, this may be overtreatment for many patients with DCIS, particularly those with small lesions detected by a mammogram.
There is increasing evidence that in these patients the risk of a breast cancer recurrence diminishes when they are treated with conservative surgery resulting in wide surgical removal and negative margins, followed by postoperative radiation. The most important thing to know — with either lumpectomy or mastectomy — is that the prognosis for complete recovery is excellent.