In a Chinese phase III trial reported in the Journal of Clinical Oncology, Wang et al found that hypofractionated radiotherapy (HFRT) and conventionally fractionated radiotherapy (CFRT) following breast-conserving surgery were associated with similar low 5-year local recurrence rates in women with breast cancer.
As stated by the investigators, “No randomized trials have compared HFRT with CFRT after breast-conserving surgery in the Asian population. This study aimed to determine whether a 3.5-week schedule of HFRT is noninferior to a standard 6-week schedule of CFRT in China.”
Study Details
In the multicenter trial, 734 women who had undergone breast-conserving surgery and had T1-2N0-3 invasive breast cancer were randomly assigned between August 2010 and November 2015 to receive HFRT (n = 368) or CFRT (n = 366). Treatment consisted of whole-breast irradiation with or without nodal irradiation, followed by a tumor-bed boost, at a dose of either 50 Gy in 25 fractions over 5 weeks with a boost of 10 Gy in 5 fractions over 1 week (CFRT), or 43.5 Gy in 15 fractions over 3 weeks with a boost of 8.7 Gy in 3 daily fractions (HFRT). The primary endpoint was 5-year local recurrence, with a 5% margin used to establish noninferiority.
Local Recurrence and Other Outcomes
Median follow-up was 73.5 months. The 5-year cumulative incidence of local recurrence was 1.2% in the HFRT group vs 2.0% in the CFRT group (hazard ratio [HR] = 0.62, 95% confidence interval = 0.20–1.88, P = .017 for noninferiority).
KEY POINTS
- 5-year local recurrence with HFRT (1.2%) was noninferior to that with CFRT (2.0%).
- No significant differences were observed in 5-year locoregional recurrence, disease-free survival, or overall survival.
The 5-year cumulative incidence of locoregional recurrence was 3.1% in the HFRT group vs 3.8% in the CFRT group (HR = 1.15, P = .725). Disease-free survival at 5 years was 93.0% vs 94.1% (HR = 1.24, P = .422). Overall survival at 5 years was 97.5% vs 98.0% (HR = 1.20, P = .680).
Toxicity and Cosmesis
No significant difference in acute toxicities, including pneumonitis/pulmonary infiltrates, were observed between treatment groups, except for a reduced incidence of grade 2 or 3 skin toxicity in the HFRT group (3.0% vs 7.5%, P = .019). No significant differences were observed in late toxicities, including lymphedema, shoulder mobility, lung fibrosis, and ischemic heart disease.
The incidence of excellent/good breast cosmesis at baseline prior to radiotherapy was 89.9% in the HFRT group and 88.5% in the CFRT group (P = .550). Among 688 patients (94.4% of total population) with cosmetic assessment at 3 years, the incidence of excellent/good (89.0% vs 88.7%) breast cosmesis, breast pain (5.5% vs 5.8%, all mild), and breast induration (eg, scar area = 6.1% vs 6.4%) was similar in the treatment groups.
The investigators concluded, “CFRT and HFRT with a tumor-bed boost may have similar low local recurrence and toxicity.”
Ye-Xiong Li, MD, of the National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences, and Peking Union Medical College, Beijing, is the corresponding author for the Journal of Clinical Oncology article.
Disclosure: The study was supported by the Chinese Academy of Medical Science Innovation Fund for Medical Sciences, National Key Projects of Research and Development of China, and Beijing Marathon of Hope, Cancer Foundation of China. For full disclosures of the study authors, visit ascopubs.org.
