The NRG Oncology (NRG)/NSABP B-39/RTOG 0413 clinical trial compared whole-breast irradiation (WBI) to accelerated partial-breast irradiation (APBI) and determined that APBI was not statistically equivalent to WBI in local tumour control. The secondary outcome for the trial was Quality-of-life (QOL).

The study enrolled 4,210 patients with Stage , 0I, or II breast cancer resected by lumpectomy; tumour size ≤ 3.0cm; and no more than 3 histologically positive nodes with the primary aim to determine whether partial breast irradiation (PBI) limited to the region of the tumour bed following lumpectomy provided equivalent local tumour control in the breast compared to conventional whole breast irradiation (WBI) in the local management of early stage breast cancer.

The QOL sub-study provided an in-depth evaluation of fatigue and treatment toxicities using well-established patient-reported-outcomes measures.

With a target accrual of 964 patients (482 with clinician intent to prescribe chemotherapy and 482 without), the QOL sub-study used validated self-report questionnaires including the Breast Cancer Treatment Outcome Scale (BCTOS) and the SF-36 vitality scale.

Assessments occurred before randomization, at completion of chemotherapy or radiotherapy, 4-weeks later, and at 6-, 12-, 24-, and 36-months.

The primary aims for the QOL sub-study were cosmesis change equivalency and fatigue change superiority for APBI vs WBI, according to patient groups treated with or without chemotherapy.

Cosmetic outcomes were similar for APBI and WBI groups, with small statistically significant differences in other outcomes that varied over time.

Differences in fatigue and other symptoms appeared to resolve by ≥6 months.

APBI may be preferred by some patients, for whom extended treatment is burdensome.

“Partial- and whole-breast radiation have equivalent cosmetic outcomes at 3 years post-lumpectomy in breast cancer patients, but significantly greater end-of-treatment fatigue occurred in patients receiving whole breast irradiation after lumpectomy without chemotherapy,” stated Patricia Ganz, MD, of the University of California Los Angeles, and Behavioural and Health Outcomes Officer for the trial.

Source: NRG Oncology