DENVER-In patients with noninflammatory locally advanced breast cancer (LABC), hyperfractionated radiation of the chest wall does not improve clinical outcomes relative to conventional radiation, according to long-term results of a trial presented at the 47th Annual Meeting of the American Society for Therapeutic Radiology and Oncology (abstract 2008).
Investigators at M.D. Anderson Cancer Center undertook the randomized phase III trial to determine if altering the schedule of radiation improves the efficacy of radiation therapy in patients with LABC, lead author Thomas A. Buchholz, MD, told ONI in an interview. In particular, he and his colleagues note, some patients continue to have a risk of locoregional recurrence despite neoadjuvant chemotherapy, mastectomy, and conventional postmastec-tomy radiation therapy.
The patients studied were women with noninflammatory LABC participating in a trial of neoadjuvant chemotherapy (vincristine, doxorubicin(Drug information on doxorubicin), cyclophosphamide(Drug information on cyclophosphamide), and prednisone(Drug information on prednisone)). A subset of 108 patients who underwent mastectomy were assigned to receive radiation therapy to the chest wall and internal mammary chain delivered either once-daily (50 Gy in 25 fractions, followed by a chest wall boost of 10 Gy) or twice-daily (60 Gy in 50 fractions, followed by a chest wall boost of 12 Gy). In addition, all patients received 50 Gy to the supraclavicular fossa and axillary apex.
Characteristics of the treatment groups did not differ significantly. In both groups, the majority of patients were 41 to 60 years old and had stage IIIA or IIIB, T3N0-1 tumors with positive or unknown estrogen-receptor status, and pathologic node-positive disease. Pathologic tumor size exceeded 2 cm in about half of patients and was unknown in about one-fifth.
Safety and Efficacy Results
In safety analyses, the incidence of any grade 3 or higher acute toxicity did not differ significantly between the once-daily and twice-daily radiation therapy groups (4% vs 5%, respectively), although the incidence of moderate moist desquamation tended to be lower with once-daily radiation (28% vs 42%).
With a median follow-up of 15 years, the actuarial rate of moderate-to-severe late toxicity did not differ significantly between the once-daily and twice-daily groups (6% vs 11%). The severe late events were rib fractures (2 cases), leukemia (2), soft tissue necrosis (2), severe telangiectasia (1), and severe cellulitis (1).