Partial Breast Irradiation Offers Some Improvements in Patient-Reported Outcomes in Breast Cancer

In patients with breast cancer who were not receiving chemotherapy, partial breast irradiation (PBI) offered a more convenient option than whole breast radiation (WBI), with less fatigue and slightly poorer cosmetic outcomes at 36 months, according to new research. In women who did receive chemotherapy, the two types of radiation offered equivalent cosmesis.

Patricia A. Ganz, MD, of the UCLA Jonsson Comprehensive Cancer Center, presented results of a quality-of-life (QOL) substudy of the NSABP B-39/RTOG 0413 trial at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting (abstract 508). The trial’s efficacy outcomes were reported previously, and PBI was statistically inferior to WBI, though with clinically small differences; the authors examined QOL outcomes with the hypothesis that PBI may be a reasonable option in some women.

The study used the Breast Cancer Treatment Outcomes Scale (BCTOS) to examine cosmesis outcomes and pain; the SF-36 vitality scale to examine fatigue; and also assessed treatment-related symptoms and convenience of care. It included a total of 975 patients, of which 950 had follow-up data; 504 patients had no chemotherapy, and 446 had chemotherapy.

Ganz said that the substudy patients’ characteristics reflected the full main study of over 4,000 women. Most women were age 50 to 70 years (60.9%), most were white (90.9%), and most were postmenopausal (68.3%). Most patients had estrogen receptor– and/or progesterone receptor–positive disease (77.1%), and most underwent axillary dissection (73.6%).

In the patients who did not receive chemotherapy, those who underwent PBI had significantly less fatigue at the end of treatment (P = .011). PBI did not meet the criteria for cosmesis equivalence at 3 years, Ganz said.

In the chemotherapy group, PBI patients had more fatigue than WBI patients (P = .011) at the end of treatment, but PBI and WBI had equivalent cosmesis at 3 years. With or without chemotherapy, patients undergoing PBI reported less breast pain at the end of treatment, and treatment-related symptoms were worse with WBI. PBI was found to be a more convenient treatment in the group that did not receive chemotherapy.

“The size of the differences were relatively small,” Ganz said, adding that the differences seen may have little clinical meaning. “Because of its shorter course and greater perceived convenience in women who did not receive chemotherapy, partial breast irradiation may be a good option for some patients.” This could include patients in more rural settings, or those with comorbidities.

Simon N. Powell, MD, PhD, of Memorial Sloan Kettering Cancer Center in New York, was the discussant for the abstract, and he noted that the relative similarity in terms of cosmesis between PBI and WBI does contrast with earlier research, in particular the RAPID trial, conducted in Canada. That trial found higher rates of fair to poor cosmesis with PBI. “The huge value of the [new] study is that it really shows the equivalence in outcome,” Powell said. “PBI is a viable treatment option.”