Hypofractionated vs conventional radiotherapy: Equally effective, safe after mastectomy
Hypofractionated radiotherapy (HFRT) is equally effective and safe compared with conventional fractionated RT (CFRT) in Chinese breast cancer patients who have undergone mastectomy, according to a phase III study presented at the American Society for Radiation Oncology (ASTRO) 2017 Annual Meeting. [ASTRO 2017, abstract 5]
“Our 5-year noninferiority study shows that HFRT, which shortens treatment time by 2 weeks compared with CFRT, can be used in place of CFRT in the postmastectomy setting to reduce healthcare costs and improve patient convenience,” said principle investigator Dr Shulian Wang of the Cancer Institute and Hospital, Chinese Academy of Medical Sciences, Beijing, China.
In the study, 811 high-risk Chinese women with stage II (5.4 percent) or III (94.6 percent) breast cancer were randomized to receive HFRT (43.5 Gy in 15 fractions for 3 weeks) or CFRT (50 Gy in 25 fractions for 5 weeks) to the chest wall and supraclavicular nodal region after mastectomy. The study’s primary endpoint was locoregional recurrence (LRR). [https://clinicaltrials.gov/ct2/show/NCT00793962]
Overall, the 5-year cumulative LRR rate was 92.8 percent, while 5-year rates of distant metastasis (DM), disease-free survival (DFS) and overall survival (OS) were 22.7 percent, 74.9 percent and 86 percent, respectively.
Importantly, 5-year rates of LRR (8.4 vs 6.0 percent; p=0.396), DM (21.3 vs 24.3 percent; p=0.530), DFS (75.1 vs 74.6 percent; p=0.841) and OS (84.9 vs 87.1 percent; p=0.562) were similar between HFRT and CFRT.
The incidence of symptomatic radiation pneumonitis, lymphoedema, shoulder disorder and late skin toxicity was also comparable between the two arms, but significantly fewer patients who received HFRT had grade 3 acute skin toxicity (3.5 vs 7.8 percent; p=0.008). One patient in the HFRT arm and three patients in the CFRT arm developed ischaemic heart disease.
“In China, postmastectomy radiotherapy is underused due to lack of facilities and its high cost. Currently, only about half of patients with stage III breast cancer receive radiotherapy despite evidence showing that CFRT improves outcomes in these patients,” Wang pointed out. “Our study is the first large, well-conducted randomized trial to demonstrate conclusively that HFRT to nodal regions is safe and effective after mastectomy in breast cancer patients.”
“Previous trials of HFRT have reported outcomes similar to those with CFRT in the postmastectomy setting in patients with early breast cancer,” she added.
“The study did not include women who had undergone breast reconstruction. Therefore, studies are needed to address the use of HFRT in these women,” said discussant Professor Gary Freedman of the University of Pennsylvania, Philadelphia, Pennsylvania, US. “The present study is large. Its 5-year results are sufficient to conclude that HFRT is suitable after mastectomy in breast cancer patients without breast reconstruction.”
“The use of HFRT after mastectomy and breast reconstruction will be evaluated in the upcoming ALLIANCE trial, which will recruit more than 800 breast cancer patients in the US. The primary endpoint will be reconstruction complications,” he added.