Long-term outcomes of breast cancer patients participating in a clinical trial evaluating the effectiveness of accelerated partial-breast irradiation (APBI) continue to be favorable, according to a presentation in San Francisco last week at the American Society of Clinical Oncology's (ASCO) Breast Cancer Symposium (BCS).
Radiation Therapy Oncology Group (RTOG) 9517 is a phase I/II trial that began enrolling patients with stage I and II breast cancer in 1997. Its objective was to evaluate the local control rate, overall survival, complication rates, and cosmetic results of patients treated with multicatheter breast brachytherapy following breast conservation surgery. A total of 98 patients treated at six cancer treatment facilities enrolled in the clinical trial.
Patients were eligible if they had a unifocal tumor less than 3 cm in size, no more than three positive lymph nodes, and negative surgical margins. Sixty-five patients received high-dose-rate brachytherapy with a dose of 34 Gy delivered in 10 fractions over five days. The remainder received a low-dose treatment of 45 Gy delivered in three to five days.
The patients had a median age of 62 at the time of treatment. The majority (88%) had T1 tumors and no nodal involvement (81%). One-third were prescribed adjuvant chemotherapy, and 64% received antiendocrine therapy. To date, patients have been followed for a median of 12.1 years
Dr. Julia White, professor of radiation oncology and director of breast radiation oncology at Ohio State University Comprehensive Cancer Center, reported that six patients had an ipsilateral breast failure, for a 10-year failure rate of 6.2%. Two of these failures occurred outside the brachytherapy treatment field. Five patients experienced regional failure and five patients were diagnosed with contralateral breast cancer. A total of 11 patients developed distant failure.
To date, eight patients have died of breast cancer and 22 have died from other causes. Ten-year rates of overall survival were 78.9%. Disease-free survival rates were 69.8%, and relapse-free survival rates were 71.9%.
Commenting upon White's presentation, Dr. Bruce Haffty, professor and chair of the department of radiation oncology at Robert Wood Johnson Medical School, said the study supports the long-term effectiveness of APBI, with acceptable local control and disease-free and survival rates.
