THE BENEFIT AND RISK OF POSTMASTECTOMY RADIATION-THERAPY IN PATIENTS WITH HIGH-RISK BREAST-CANCER

To evaluate the efficacy of postmastectomy radiation therapy (PMRT) fo r prophylaxis against locoregional recurrence in high-risk boast cance r patients, and the rate of complication associated with such treatmen t, we retrospectively reviewed 79 breast cancers in 78 patients, who w ere given therapy (PMRT) between April 1990 and March 1995. Radiation doses were 46-50 Gy in 2-Gy fractions. High-risk factors included prim ary tumor (greater than or equal to 5 cm) in 19 (24.1%) patients, posi tive axillary lymph nodes (greater than or equal to 4) in 56 (70.9%) p atients, positive or close (less than or equal to 2 mm) surgical margi ns in 14 (17.7%) patients, and central or inner quadrant tumor with po sitive axillary nodes and lymphovascular invasion in seven (8.9%) pati ents. Adjuvant chemotherapy was also given to 69 of 78 (88.5%), patien ts and hormonal therapy to 41 of 78 (53.7%) patients. The median follo w-up time was 25 months (range, 7-66 months) after mastectomy. Our stu dy revealed that locoregional failure as the first site of failure occ urred in only one of 78 (1.3%) patients. Relapse-free survival at 3 ye ars was 67.7% [95% confidence interval (CI), 52.0-81.3], and overall s urvival was 76.9% (95% CI, 63.3-90.6). The incidence of radiological e vidence of lung fibrosis increased significantly in patients whose int ernal mammary chain was included in the radiation field. The occurrenc e of lung fibrosis can he reduced by changing radiation treatment tech nique and keeping central lung distance (CLD) of tangential field to l ess than or equal to 2.8 cm in tangential field technique or less than or equal to 1.4 cm in tangential with a separate internal mammary fie ld technique. We concluded that the risk of locoregional recurrence in high-risk breast cancer patients can be much reduced by PMRT. With ca reful selection of radiation treatment fields, radiotherapy technique, and limitation of CLD to less than or equal to 2.8 cm in tangential t echnique or less than or equal to 1.4 cm in separate technique, the ri sk of symptomatic radiation pneumonitis is minimal. PMRT should be rec ommended for breast cancer patients who are at high risk for locoregio nal recurrence.