Radiation therapy following mastectomy for axillary node-positive breast cancer: indication of chest wall irradiation.

This retrospective study was conducted to determine the indication of chest wall irradiation following mastectomy in axillary node-positive breast cancer patients. Between 1982 and 1993, 103 women with axillary node-positive breast cancer received postoperative radiation therapy following mastectomy using the hockey-stick field, which included the ipsilateral supraclavicular fossa and internal mammary nodes, without the chest wall. Ages ranged from 33 to 73 years (median: 47). Thirty-five patients underwent modified radical mastectomy, 48 radical mastectomy, and 20 extended radical mastectomy. Twenty-two patients had 1-3 positive axillary nodes, and 81 had 4 or more positive axillary nodes. The total doses ranged from 42 to 64 Gy (median 54 Gy) with a daily fraction size of 2 Gy. Adjuvant chemotherapy was given to 75 patients, and hormone therapy was administered to 78 patients. The median follow-up time was 121 months (range, 68-191 months) for the 57 surviving patients. The actuarial overall survival rate and the chest wall control rate at 10 years for all patients were 55% and 85%, respectively. Of the 103 patients, 14 developed chest wall recurrence. In the analysis, status of vascular invasion alone had a significant impact on chest wall control. In patients with definite vascular invasion, 2 of 5 (40%) patients with 1 to 3 positive axillary nodes, and 10 of 31 (32%) with 4 or more positive axillary nodes developed chest wall recurrence. In contrast, no patients without definite vascular invasion developed chest wall recurrence. Factors such as age, menopausal status, pathology, tumor location, extent of resection, estrogen receptor status, total dose, chemotherapy, and hormone therapy did not influence the development of chest wall recurrence. Among node-positive breast cancer patients following mastectomy, those with definite vascular invasion should be delivered chest wall irradiation regardless of the number of positive axillary nodes. In contrast, those without definite vascular invasion need not be administered chest wall irradiation.