Chemotherapy plus radiation therapy (chemoradiotherapy) was not associated with improved relapse-free survival versus chemotherapy alone in patients with stage III or IVA endometrial cancer, according to results from a phase 3 trial.
“This combined approach has been studied, but its efficacy relative to that of chemotherapy alone is not known,” wrote Daniela Matei, MD, of Northwestern University, Chicago, and colleagues. The results were published in the.
The Gynecologic Oncology Group (GOG) 258 study included 736 patients with stage III or IVA endometrial carcinoma who were randomized in a 1:1 fashion to receive platinum-based chemotherapy plus volume–directed external-beam radiation therapy every 21 days for a total of four cycles or chemotherapy alone every 21 days for a total of six cycles.
The primary endpoint measured was relapse-free survival; secondary endpoints included safety, overall survival (OS), and quality of life.
At 60 months, the proportion of patients alive and relapse free was 59% (95% confidence interval, 53-65) and 58% (95% CI, 53-64) in the chemoradiotherapy and chemotherapy alone arms, respectively (hazard ratio, 0.90; 90% CI, 0.74-1.10).
“The data on overall survival are not sufficiently mature to allow comparison between the groups,” the researchers wrote.
With respect to safety, grade 3, 4, or 5 toxicities were reported in 58% and 63% of patients in the chemoradiotherapy and chemotherapy alone arms, respectively.
“Although acute toxic effects were more common in the chemoradiotherapy group than in the chemotherapy-only group in our trial, most were low-grade and reversible on treatment discontinuation,” Dr. Matei and colleagues explained.
A major strength of the study was the broad inclusion criteria, which included patients with nonperitoneal, lymph-node, pelvic, and adnexal metastasis, the researchers noted.
“Our data are compatible with the hypothesis from previous studies that completion of chemotherapy is important for the prevention of distant relapse,” they concluded.
The National Cancer Institute supported the study. The authors reported financial affiliations with AstraZeneca, Clovis, Genentech, the GOG Foundation, Tesaro, and several others.
SOURCE: Matei D et al. N Engl J Med. 2019 Jun 13. .