New ASTRO Guidelines Recommend Hypofractionated Breast Irradiation

An expert panel convened by the American Society for Radiation Oncology (ASTRO) released a set of recommendations regarding fractionation for whole-breast irradiation (WBI) in women with breast cancer. The guideline includes recommendations for standard practice, factors that should influence fractionation decision making, and issues surrounding tumor bed boost, among other issues.

“Breast cancer is the most common malignancy treated with radiation therapy in the United States, and WBI is the most common radiotherapeutic approach for breast cancer,” wrote authors led by Benjamin D. Smith, MD, of MD Anderson Cancer Center in Houston. The standard of care for WBI has involved conventional fractionation (CF), with daily doses of 180 to 200 cGy up to approximately 4,500 to 5,000 cGy; research in the 1990s and 2000s looked into whether moderate hypofractionation (HF) with daily doses of 265 to 330 cGy could offer similar outcomes.

“Although the evidence supporting HF-WBI has subsequently grown substantially, adoption of HF-WBI among appropriate patients remains low,” the authors wrote. The new guideline was aimed at reducing variability in treatment, while allowing better individualization of therapy. The guideline was published in Practical Radiation Oncology.

The task force convened by ASTRO conducted a literature review for a series of key questions. The primary recommendation is that for women with invasive breast cancer receiving WBI with or without inclusion of the low axilla, hypofractionated WBI is preferred. Specifically, the guideline recommends a WBI dose of 4,000 cGy in 15 fractions, or of 4,250 cGy in 16 fractions. The decision to offer HF-WBI should be made independently of tumor grade, and may be independent of hormone receptor status, HER2 receptor status, and margin status. It notes specifically that there is no evidence of deleterious effects of HF-WBI compared with CF-WBI in any age of patients, and thus hypofractionation can be offered to all patients regardless of age.

A tumor bed boost is recommended for patients aged 50 years or younger with any grade tumor, or in patients aged 51 to 70 years with high-grade tumors or positive margins. Other recommendations are also included, such as for treatment planning, technique of WBI, patient positioning, and other factors.

“It is hoped the physician contribution to variability in care will…be decreased and decisions more appropriately individualized based on tumor factors, anatomic considerations, and patient preferences,” the authors wrote.