Accelerated partial breast irradiation (APBI) with 3-D external beam radiation therapy (3-D CRT) for breast cancer patients who have undergone breast conserving surgery (BCS) yields worse cosmetic outcomes than whole breast irradiation (WBI), according to research presented at the American Society for Radiation Oncology’s (ASTRO’s) 54th Annual Meeting.

Radiation can cause fibrosis or thickening of breast tissue, which can lead to distortion of the treated breast after surgery and can adversely affect a patient’s cosmetic result.

This study reports on the interim toxicity results of a multi-center, randomized trial comparing 3-D CRT APBI to standard WBI in breast cancer patients previously treated with BCS.

The study includes 2,135 women over the age of 40 who had invasive or non-invasive breast cancer less than three centimeters in size and were treated with BCS between February 2006 and July 2011.

Patients were randomized into two groups: those who were given 3-D CRT APBI of 38.5 Gy in 10 fractions twice daily, and those who received WBI of 50 Gy in 25 fractions or 42.5 Gy in 16 fractions given once daily +/- boost irradiation.

Cosmetic outcome (cosmesis) was assessed by a trained study nurse and the patients at baseline, three and five years after treatment as well as by a panel of radiation oncologists who reviewed unlabeled digital photographs.

Patient results for cosmesis were rated using the European Organisation for Research and Treatment of Cancer (EORTC) Cosmetic Rating System for Breast Cancer and for toxicity using the NCI Common Terminology Criteria for Adverse Events (v. 3). Negative cosmesis results were compiled for ratings of at least “fair” or “poor” versus “very good” or “excellent.” The study is still in process and reports an interim safety analysis at a median follow-up of 2.5 years.

At three years post-treatment 850 patients were assessed by nurses. Thirty-two percent of patients were observed to have adverse cosmesis with APBI in comparison to 19 percent of patients treated with WBI. Oncologists and patients provided similar assessments in the rate of observed adverse cosmesis with APBI vs. WBI. Grade 1 and 2 late radiation toxicities, such as breast induration, were higher in the group receiving APBI compared to those receiving WBI. Grade 3 and 4 toxicities were rare in both treatment groups.

“Women with early-stage breast cancer who undergo breast conserving surgery may be offered accelerated partial breast irradiation as part of their treatment,” said Timothy J. Whelan, MD, lead author of the study and a radiation oncologist at Juravinski Cancer Centre in Hamilton, Ontario. “Our study supports earlier Phase II trial research and found that APBI using 3-D external beam radiation therapy can increase the risk of moderate radiation side effects, which may affect cosmetic outcome for some patients. 3-D CRT APBI treatment needs additional research.”

The abstract, “Interim Toxicity Results from RAPID: A Randomized Trial of Accelerated Partial Breast Irradiation (APBI) Using 3-D Conformal External Beam Radiation Therapy (3-D CRT),” was presented in detail during the plenary session at ASTRO’s 54th Annual Meeting.

Source: ASTRO