Long-term outcome after postmastectomy radiation therapy for the treatment of ductal carcinoma in situ of the breast.

Postmastectomy radiation therapy may be recommended for patients with a high risk for local recurrence after mastectomy for ductal carcinoma in situ (DCIS). However, long-term outcomes after postmastectomy radiation therapy are not well described. This study was performed to determine long-term outcomes in patients treated with radiation therapy after mastectomy for DCIS. The authors reviewed the records of all patients with breast cancer treated with postmastectomy radiation therapy between 1978 and 1992. Of 287 total patients treated, three (1%) were for DCIS. These three patients had diffuse microcalcifications on screening mammography. The reason for postmastectomy radiation therapy was a potentially increased risk for local recurrence because of a positive resection margin after mastectomy for DCIS. Surgery consisted of a total mastectomy (n = 2) or a modified radical mastectomy (n = 1). Radiation therapy consisted of 4275-5000 cGy to the chest wall in 200-225 cGy fractions. The energy used was 6-MV photons (n = 2) or 15-MV photons (n = 1). No regional nodal irradiation was used. Bolus was applied to the chest wall every other day in one of the three patients. One patient was treated with a scar boost after chest wall irradiation (boost dose, 1000 cGy; total dose, 5275 cGy). The median age for the three patients was 46 years (range, 41-68 years). No patient received adjuvant chemotherapy or hormonal therapy. With a minimum follow-up of 7.1 years (median, 7.4 years; range, 7.1-19.4 years), no local-regional recurrence or evidence of metastatic disease developed in any of the patients. No long-term complication from radiation therapy was noted, and no contralateral breast cancer developed. All patients were alive and free of relapse at the last follow-up. The use of radiation therapy in this group of three patients has shown no evidence of relapse with a minimum of 7.1 years of follow-up. The authors conclude that radiation therapy may be indicated after mastectomy for DCIS to reduce the risk of recurrence for high-risk patients.