REDUCING A POSTOPERATIVE RADIATION DOSE IN THE COMBINED-MODALITY TREATMENT OF LOCALLY ADVANCED BREAST CANCER
The purpose of the study was to evaluate the efficiency of traditional versus low-dose postmastectomy chest radiation according to local control criteria, overall and relapse-free survival rates, and the frequency of postradiation cardiac complications. The efficiency of treatment was compared in two groups of patients with Stages II-IIIB breast cancer: 1) 129 patients who received normal-dose (50 Gy in 25 fractions applied to the chest) radiotherapy (RT) and 2) 82 patients who had low-dose (40 Gy in 20 fractions applied to the chest) RT. The latter followed Madden mastectomy in all cases. In all the patients, regional areas were irradiated with standard doses of 46-50 Gy concurrently with chest radiation. The frequency and quality of neoadjuvant and adjuvant chemotherapy were similar in the groups. The median follow-up was 111 and 95 months in each group, respectively. In the normal- and low-dose RT groups, 5-year actuarial local-regional progression rates were 6.2±2.1 and 3.7±2.1%, respectively (p = 0.4). In Groups 1 and 2, late metastases were detected in 34.6±4.2 and 19.5±4.4%, respectively (p < 0.05). Five-year actuarial relapse-free survival was 71.5±6.4% in the low-dose RT group and 53.5±5.4% in the normal-dose RT one, respectively (p = 0.07). Five-year overall survival was 65.3±5.6 and 72.2±6.3%, respectively (p = 0.08). The patients with a left-sided tumor process were noted to have late ECG cardiac changes in 55±11.1% of cases in the low-dose RT group and in 75±9.7% in the normal-dose RT one (p > 0.05). The findings suggest that there are no statistically significant differences in the rates of local-regional progression, overall and relapse-free survival in the normal- and low-dose RT groups. The proposed procedure for reduced postmastectomy chest radiation in combination with current chemotherapy regimens can reduce the risk of cardiac toxicity, without decreasing the therapeutic effectiveness characteristic of the traditional procedure.