BRACHYTHERAPY OR ELECTRON-BEAM BOOST IN CONSERVATION THERAPY OF CARCINOMA OF THE BREAST - A NONRANDOMIZED COMPARISON

Purpose: The results of breast-conservation therapy using breast irrad iation and a boost to the tumor excision site with either electron bea m or interstitial Ir-192 implant are reviewed. Methods and Materials: A total of 701 patients with histologically confirmed Stage T1 and T2 carcinoma of the breast were treated with wide local tumor excision or quadrantectomy and breast irradiation. The breast was treated with ta ngential fields using 4 or 6 MV photons to deliver 48 to 50 Gy in 1.8 to 2 Gy daily dose, in five weekly fractions. In 80 patients the regio nal lymphatics were irradiated. In 342 patients with Stage T1 and 107 with Stage T2 tumors, boost to the primary tumor excision site was del ivered with 9 MeV and, more frequently, with 12 MeV electrons. In 91 p atients with Stage T1 and 38 patients with Stage T2 tumors an intersti tial Ir-192 implant was performed. Tumor control, disease-free surviva l, cosmesis, and morbidity of therapy are reviewed. Minimum follow-up is 4 years (median, 5.6 years; maximum, 24 years). Results: The overal l local tumor recurrence rates were 5% in the T1 and 11% in the T2 tum or groups. There was no significant difference in the breast relapse r ate in patients treated with either electron beam or interstitial Ir-1 92 boost. Regional lymph node recurrences were 1% in patients with T1 and 5% with T2 tumors. Distant metastases were recorded in 5% of the T 1 and 23% of the T2 groups. The 10-year actuarial disease-free surviva l rates were 87% for patients with T1 and 75% for patients with T2 tum ors. Disease-free survival was exactly the same in patients receiving either electron beam or interstitial Ir-192 boost. Cosmesis was rated as excellent/good in 84% of patients with T1 tumors treated with elect ron beam and 81% of patients treated with interstitial implant, and 74 and 79%, respectively, in patients with T2 tumors. Conclusions: Breas t-conservation therapy is an effective treatment for patients with T1 and T2 carcinoma of the breast. There is no significant difference in local tumor control, disease-free survival, cosmesis, or morbidity in patients treated with either electron beam or interstitial Ir-192 impl ant boost. Clinical trials in progress will further elucidate this con troversial subject.