Accelerated Hypofractionated Whole-Breast Irradiation Yields Excellent Control and Cosmesis

December 14, 2007

After breast-conserving surgery, a shorter radiotherapy regimen using accelerated hypofractionated whole-breast irradiation (AHWBI) is as effective and cosmetically acceptable as standard whole-breast irradiation (SWBI), according to the 12-year follow-up of a study by the Ontario Clinical Oncology Group.

After breast-conserving surgery, a shorter radiotherapy regimen using accelerated hypofractionated whole-breast irradiation (AHWBI) is as effective and cosmetically acceptable as standard whole-breast irradiation (SWBI), according to the 12-year follow-up of a study by the Ontario Clinical Oncology Group.

Tim Whelan, PhD
Photo Courtesy @ SABCS/Todd Buchanan 2007

Local recurrence rates, overall survival, and cosmesis were essentially identical between the two arms, said Tim Whelan, MD, professor of oncology and head of the radiation therapy program at Juravinski Cancer Center, McMaster University in Hamilton, OT. WBI is an integral part of breast-conserving therapy in that it reduces the risk of local recurrence and avoids mastectomy. Yet despite its benefits, up to 30% of women do not receive this treatment, largely because of inconvenience and cost, he said. WBI is usually given as 50 Gy (2 Gy daily) in 25 fractions over 5 weeks, with or without boost irradiation. Data from trials in the U.K. and Canada have suggested that accelerated and/or hypofractionated (larger dose per fraction) WBI can be just as effective. This approach involves less treatment time for the patient, giving 40 to 42.5 Gy in 15 or 16 fractions over 3 weeks in daily fractions of 2.7 Gy. The study presented by Dr. Whelan recruited 1234 node-negative patients who had undergone lumpectomy between 1993 and 1996 and randomized them to SWBI or AHWBI. The SWBI approach treated the whole breast in two opposed tangential fields and used wedge compensation to assure a uniform dose at midfield. At 5 years, local recurrences were observed in 3% of each arm and cosmesis was similar. "As a result of these findings, there was an increasing adoption of AHWBI across Canada, the U.K., and parts of Europe; however, concerns remained regarding long-term morbidity, and AHWBI was still not widely used in the U.S.," Dr. Whelan said. Updated results from the study presented at SABCS showed local recurrence rates to be 6.2% for SWBI and 6.7% for AHWBI. Overall survival was 84.4% and 84.6%, respectively. Local recurrence rates were higher for patients <50 years of age, patients with larger tumor size, and patients not receiving systemic therapy, but there were no differences according to treatment arm. "There was no evidence that AHWBI is less effective in these high-risk groups," he said. Cosmetic outcome, an indication of late morbidity, was assessed by trained clinical trials nurses according to the EORTC Cosmetic Rating System. The percentage of patients deemed to have excellent or good cosmetic outcome at 10 years was 71% with SWBI and 70% with AHWBI. Late radiation morbidity was also similar, observed in skin in 8% and 9%, respectively, and in subcutaneous tissue in 11% and 12%, respectively. No patients developed grade 4 toxicity. In questioning from the audience, Dr. Whelan noted that AHWBI is being used mostly in stage II patients but not in stage III patients, who usually undergo mastectomy. He added that the AHWBI approach in this study did not incorporate boost irradiation, which is being incorporated into other experimental AHWBI protocols. He said he would use boosts in patients at "sufficient risk to derive benefit from it." "Based on a series of randomized trials over the past 10 years, boost irradiation has been widely adopted, but AHWBI is still infrequent. I would encourage the broader use of this proven modality. It has important advantages for women who want to be treated in a shorter period of time," he said.

Disclosures:

The author(s) have no significant financial interest or other relationship with the manufacturers of any products or providers of any service mentioned in this article.