By Will Boggs MD
NEW YORK (Reuters Health) - Cosmetic outcomes after hypofractionated (HF) whole-breast irradiation (WBI) are at least as good as after conventionally fractionated (CF) WBI, according to three-year results from a randomized noninferiority trial.
"Not only was HF-WBI not inferior to CF-WBI, it actually seemed to be a little bit better," Dr. Benjamin D. Smith from University of Texas MD Anderson Cancer Center, Houston, told Reuters Health by email. "HF-WBI was particularly better in the subgroup of women with large breast size; that was a big surprise, because historically HF-WBI was thought to be relatively contraindicated in women with large breast size."
Dr. Smith and colleagues compared the proportion of women with adverse cosmetic outcomes after CF-WBI (50 Gy in 25 fractions + 10-14 Gy in 5-7 fractions) or HF-WBI (42.56 Gy in 16 fractions + 10-12.5 Gy in 4-5 fractions).
All 149 women assigned to CF-WBI and 99% of the 137 women assigned to HF-WBI received the protocol-specified WBI and boost doses. Median follow-up time was 4 years (range, 0.2 to 6.0 years).
The proportion of women with adverse patient-reported cosmesis at three years, the primary outcome, was 8.2% with HF-WBI versus 13.6% with CF-WBI, which satisfied the noninferiority criterion, according to the October 31st Journal of Clinical Oncology online report.
Among women treated with chemotherapy, however, adverse cosmetic outcome rates were 4.1 percentage points higher with HF-WBI than with CF-WBI, leaving the question of noninferiority inconclusive.
In contrast, adverse cosmetic outcome rates in large-breasted women were 18.6 percentage points lower with HF-WBI, suggesting its superiority in this regard over CF-WBI.
The two groups did not differ significantly in three-year patient-reported adverse functional status, breast pain, or well-being.
Physician-rated cosmesis at three years did not differ between the groups, nor did toxicity rates.
"Our findings support the ASTRO (American Society for Therapeutic Radiology and Oncology) evidence-based guideline, which concluded that HF-WBI should be preferred for the vast majority of women with early breast cancer in the United States who require whole breast irradiation," Dr. Smith said.
He added, "These findings should help radiation oncologists to feel more comfortable offering HF-WBI to their patients, particularly as the patient population, treatment approach, and concomitant systemic therapy used in our trial mirror current practice."
Dr. Chirag Shah from Ohio's Cleveland Clinic, who has researched various aspects of WBI, told Reuters Health by email, "The main take away is that HF-WBI is a standard option for women with early stage breast cancer and that CF-WBI really should be used in a limited way based on the results and the previous studies performed."
"The most surprising finding was that in large-breasted patients, adverse cosmetic outcomes were 18.6% lower than conventional treatment," he said. "I think this shows that HF-WBI can be used in large breasted patients as well as those receiving chemotherapy, consistent with updated ASTRO guidelines."
"We expect shorter schedules still in the years to come," Dr. Shah said.
Dr. Bruce G. Haffty from Rutgers Cancer Institute of New Jersey in New Brunswick, who has also extensively researched breast radiation therapy, told Reuters Health in an email, "Shorter courses of therapy should be considered in the majority of patients who are being treated to the whole breast without regional nodal radiation. There may still be circumstances where the longer course of therapy is preferable, but patients should be aware that the shorter course of therapy is acceptable in a majority of cases."
"Patients treated for breast cancer have a number of options regarding local-regional treatment, and decision making regarding the most appropriate treatment involves informed and shared decision making between the patient and her treating physicians," he said.
J Clin Oncol 2018.
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