Differences in the Acute Toxic Effects of Breast Radiotherapy by Fractionation Schedule: Comparative Analysis of Physician-Assessed and Patient-Reported Outcomes in a Large Multicenter Cohort.

IMPORTANCE

Randomized trials have established the long-term safety and efficacy of hypofractionated whole-breast radiotherapy, but little is known about the acute toxic effects experienced by patients treated with hypofractionation as compared with conventional fractionation, particularly in real-world settings and from the patient's own perspective.

OBJECTIVE

To evaluate prospectively collected data on acute toxic effects and patient-reported outcomes in a cohort treated with varying radiation fractionation schemes in practices collaborating in the Michigan Radiation Oncology Quality Consortium (MROQC).

DESIGN, SETTING, AND

PARTICIPANTS

We compared toxic effects in patients receiving hypofractionation (HF) vs conventional fractionation (CF) during treatment (through 7 days after treatment) and in follow-up (posttreatment days 8-210), after adjustment for sociodemographic, clinical, and treatment characteristics. The MROQC includes academic and community radiation oncology practices across Michigan. All 2604 patients who received adjuvant whole-breast radiotherapy after lumpectomy for unilateral breast cancer at MROQC participating sites from October 2011 through June 2014 were registered; we analyzed 2309 for whom there was a comprehensive physician toxicity evaluation within 1 week of completion of radiotherapy and at least 1 weekly toxicity evaluation during treatment.

EXPOSURES: Hypofractionation vs CF.

MAIN OUTCOMES AND MEASURES: Physicians reported dermatitis, pain, fatigue, and other common toxic effects associated with breast radiotherapy at baseline, weekly during radiotherapy, and in follow-up. Patients who consented also rated their own experiences, including breast pain, fatigue, and being bothered by symptoms.

RESULTS

Of the 2309 evaluable patients, 578 received HF. During treatment, after adjustment for sociodemographic, clinical, and treatment factors, patients receiving CF had significantly higher maximum physician-assessed skin reaction (moist desquamation, 28.5% vs 6.6%, P < .001; grade ≥2 dermatitis, 62.6% vs 27.4%, P < .001), self-reported pain (moderate/severe pain, 41.1% vs 24.2%, P = .003), burning/stinging bother (often/always, 38.7% vs 15.7%, P = .002), hurting bother (33.5% vs 16.0%, P = .001), swelling bother (29.6% vs 15.7%, P = .03), and fatigue (29.7% vs 18.9%, P = .02) but slightly greater absence of skin induration in follow-up (84.5% vs 81.2%, P = .02). No significant differences were observed in any other measured outcomes during follow-up extending through 6 months.

CONCLUSIONS AND RELEVANCE: Hypofractionation not only improves convenience but also may reduce acute pain, fatigue, and the extent to which patients are bothered by dermatitis in patients with breast cancer undergoing whole-breast radiotherapy.