NEW ORLEANS – Pelvic radiation was as effective for producing recurrence-free survival as vaginal cuff brachytherapy plus chemotherapy but with less acute toxicity and fewer local recurrences in women with high-risk stage I or stage II endometrial cancer in a multicenter, randomized trial with 601 patients.
These findings should result in wider use of pelvic radiation as the preferred treatment for these patients, Marcus E. Randall, MD, said at the annual meeting of the Society of Gynecologic Oncology. “It will change practice,” he predicted.
Dr. Randall and his colleagues from the Gynecologic Oncology Group (which recently became part of NRG Oncology) designed the trial, GOG-0249, to address recent interest in using vaginal cuff brachytherapy plus chemotherapy with carboplatin and paclitaxel as an alternative to the more standard approach of pelvic radiation for treating women with either high-risk stage I or stage II endometrial cancers. Clinicians had considered the brachytherapy plus chemotherapy approach a reasonable option by “extrapolating from studies with advanced” endometrial cancer, but with no direct evidence to support this alternative, Dr. Randall explained in a video interview.
To generate evidence, the researchers enrolled 601 patients at several participating U.S. centers and followed them for a median of 53 months (4.4 years), with 259 patients treated and followed in the pelvic radiation arm and 268 patients treated and followed in the brachytherapy plus chemotherapy arm. Clinicians administered the complete planned treatment regimen to 91% of patients assigned to pelvic radiation and to 87% of those assigned to brachytherapy plus chemotherapy. Three quarters of enrolled patients had high-risk stage I disease, and the entire study group averaged about 62 years old.
The trial’s primary endpoint was recurrence-free survival, which occurred in 78% of the pelvic radiation patients and 79% of brachytherapy plus chemotherapy patients after 5 years when analyzed on an intention-to-treat basis. The two subgroups also showed similar rates of overall survival during follow-up.
Although the two treatments produced essentially identical outcomes for the primary result, they showed two important differences on secondary outcomes, reported Dr. Randall, professor and chair of radiation medicine at the University of Kentucky in Lexington.
Acute adverse effects rated as grade 3 severity or higher occurred in 11% of the pelvic radiation patients and in 64% of the brachytherapy plus chemotherapy patients, although late toxicities occurred at similar rates (13% and 12%, respectively) in the two subgroups.
Local pelvic and para-aortic nodal recurrences occurred in 4% of the pelvic radiation patients and in 9% of the brachytherapy plus chemotherapy patients, a 53% relative risk reduction with pelvic radiation. The difference in the nodal recurrences was apparent within the first year of follow-up, and the difference in rates continued to steadily widen over time after that. However the rates of both vaginal and distant recurrences were very similar in the two treatment arms. Distant recurrences were the most common type of treatment failure, occurring in about 18% of patients in both subgroups during complete follow-up.
“Pelvic radiation therapy remains an appropriate and preferable treatment for high-risk, early stage endometrial carcinoma,” Dr. Randall concluded.
SOURCE: Randall ME et al. SGO 2018.