Purpose: To evaluate tolerance and efficiency of a boost dose delivered by high-dose-rate brachytherapy (HDRB) in conservative treatment of breast cancer. To evaluate the feasibility of brachytherapy on an out-patient basis.
Methods: One hundred and six patients with T1-T2, N0-N1 breast cancers (108 breasts) have been treated with lumpectomy, external irradiation (45 Gy in 5 weeks), and a boost dose on the tumor bed with HDR iridium brachytherapy. Two fractions of 5 Gy were delivered 6 or 24 hours apart. Implantation was done during the lumpectomy (group A: 24 cases) or 3 to 4 weeks after the end of external irradiation (group B: 84 cases). For group B, the application was performed on local anesthesia, and did not require hospitalization. Characteristics of the population were as follows: T1: 77 (71.3%); T2: 31 (28.7%); median tumor size: 1.5 cm; histology: intraductal carcinomas (DCIS): 14 (13%); infiltrative ductal carcinomas (IDC): 84 (77.8%); others: 10 (9.2%). For IDC, surgical margins were found positive in 15 cases, and an extensive intraductal component was present in 22 cases.
Results: All ambulatory HDR implants were performed as planned. No immediate toxicity was noticed, except 5 local hematomas. With a median follow-up of 45 months, 5 local relapses were observed (5-year local relapse rate: 5.1%). Only histological grade III was significantly correlated with local relapse. The 5-year disease-free survival and overall survival were respectively 93.8% and 93.3%. Cosmetic result was evaluated in 87 cases, and was good or excellent in 48 cases (63.2%), acceptable in 27 cases, and poor in 5 cases.
Conclusion: HDRB allows the boost dose to be performed on an out-patient basis. It seems to offer the same local control as other boost techniques for localized breast cancer with acceptable cosmetic results.