A shorter course of postmastectomy radiation therapy (PMRT) was safe and effective for patients with breast cancer undergoing breast reconstruction, and proved to be noninferior to a longer course of treatment, according to results from the phase 3 RT CHARM (Alliance A221505) study presented at the American Society for Radiation Oncology Annual Meeting (Abstract 1).
“Hypofractionated PMRT and reconstruction is noninferior to standard fractionation for reconstruction complications, toxicity, and local control,” said principal investigator Matthew M. Poppe, MD, professor of radiation oncology at the University of Utah in Salt Lake City.
Almost 50% of patients undergoing mastectomy will get breast reconstruction, explained Dr. Poppe. Standard PMRT takes four to five weeks of daily treatment, and many patients forgo this treatment because of the time involved, which may compromise survival outcomes.
RT CHARM included 898 patients with unilateral breast cancer from 209 academic and community sites. Patients could have larger (pT3N0) or smaller tumors, as well as invasion of regional lymph nodes. Patients were randomly assigned to receive either conventional radiation (50 Gy in 25 fractions over five weeks) or hypofractionated radiation (42.56 Gy in 16 fractions over approximately three weeks).
Of the patients who completed breast reconstruction during the study period, 59% had implants alone, and 41% had autologous reconstruction with or without implants.
The primary intention-to-treat analysis showed that hypofractionated PMRT was noninferior to conventional PMRT at 24 months (P=.0004). Similarly, in the as-treated analysis, hypofractionated PMRT was noninferior to conventional PMRT (P=.009).
Two years after breast reconstruction, 14% of patients who had hypofractionation experienced complications compared with 12% who received conventional PMRT. Local and locoregional recurrence rates at three years were low for both study groups, with a recurrence rate of 1.9% for conventional PMRT and 1.5% for hypofractionated PMRT.
When Dr. Poppe and colleagues looked at outcomes based on reconstruction type and timing, they found “a suggestion” that implant-only reconstruction had higher overall complication rates compared with autologous reconstruction with or without implants. In a multivariable analysis, the use of implant-only reconstruction was the only factor significantly associated with reconstruction complications. However, Dr. Poppe said that these findings should be interpreted with caution, as patients were not randomized for timing.
According to Rachel Jimenez, MD, of Massachusetts General Hospital in Boston, there were two big takeaways from this trial. “First, radiation therapy has received undeserved negative press for concerns around toxicities,” Dr. Jimenez said during a press conference. “While it is true that all cancer therapy has associated morbidity, the advances in radiation therapy have markedly and meaningfully improved safety of treatment for all patients.”
Second, the rate of complications associated with breast reconstruction was significantly lower than what was expected, regardless of the treatment group, Dr. Jimenez said.
“Whether patients received shorter or longer therapy, they can do so very safely,” Dr. Jimenez said. “Now we are really reaching critical mass of data to embrace a hypofractionated or shorter course schedule.”
Dr. Poppe has no relevant disclosures.
Dr. Jimenez has no relevant disclosures.