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

Postmastectomy radiation therapy may be recommended for patients with a hig h risk for local recurrence after mastectomy for ductal carcinoma in situ ( DCIS). However, long-term outcomes after postmastectomy radiation therapy a re not well described. This study was performed to determine long-term outc omes 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 diffus e microcalcifications on screening mammography. The reason for postmastecto my radiation therapy was a potentially increased risk for local recurrence because of a positive resection margin after mastectomy for DCIS. Surgery c onsisted 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 photo ns (n = 1). No regional nodal irradiation was used. Bolus was applied to th e 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 cG y; total dose, 5275 cGy). The median age fer the three patients was 46 year s (range, 41-68 years). No patient received adjuvant chemotherapy or hormon al 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 d isease developed in any of the patients. No long-term complication from rad iation 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.