Pelvic radiation remains standard treatment for early-stage endometrial cancer
Vaginal cuff brachytherapy with chemotherapy did not extend RFS or OS compared with pelvic radiation therapy for women with stage I or stage II high-risk endometrial cancer, according to phase 3 results of the Gynecology Oncology Group-249 trial presented at the American Society for Radiation Oncology Annual Meeting.
Further, treatment with chemotherapy and vaginal cuff brachytherapy led to poorer pelvic or para-aortic nodal control rates and more short-term adverse events.
“We need better treatment strategies to address the risk for systemic disease to further improve outcomes for these patients,” Marcus Randall, MD, FASTRO, professor of radiation medicine at University of Kentucky, said during a press conference.
Historically, adjuvant pelvic radiation therapy is standard for patients at high risk for local recurrence after surgery. However, there has been a trend toward increased use of vaginal brachytherapy.
“There is some logic to [the increased use],” Randall said. “We know from previous studies that we can come close to eliminating vaginal cuff failures with this type of therapy. ...We know that for the high-risk patients, they have 15% to 18% rate of systemic failure. [Therefore], we needed a direct comparison of the standard approach to the more experimental treatment of cuff brachytherapy and chemotherapy.”
The analysis included 601 patients (median age, 63 years), most of whom (74%) had stage I disease and endometrioid histology (71%). All patients underwent hysterectomy prior to initiation of radiation or chemoradiation therapy.
Researchers randomly assigned 301 patients to a mean dose of 45 Gy pelvic external beam radiation therapy with intensity-modulated radiation therapy or standard four-field techniques over 5 weeks. The other 300 patients received high- or low-dose rate vaginal cuff brachytherapy with 175 mg/m2 3-hour paclitaxel plus carboplatin area under the curve of 6 every 21 days for a total of three cycles.
The primary objective was to determine if vaginal cuff brachytherapy reduced recurrence or mortality rates more than pelvic radiation. Secondary objectives included OS, patterns of failure and toxicity between arms.
Overall, 91% in the pelvic radiation group and 87% in the vaginal cuff brachytherapy group completed treatment.
At median follow-up of 53 months, 82% of patients were alive and recurrence-free at 3 years for both groups.
Researchers observed no statistically significant increases in RFS or OS in the brachytherapy-chemotherapy group.
Rates of 3-year OS included 91% for the pelvic radiation arm and 88% for the brachytherapy-chemotherapy arm, which did not reach statistical significance.
Cumulative incidence of pelvic or para-aortic nodal recurrence at 5 years appeared twice as high in the brachytherapy-chemotherapy group then the pelvic radiation group (9.2% vs. 4.4%; HR = 0.47; 95% CI, 0.24-0.94).
Cumulative incidence for vaginal and distant tumor recurrences did not differ between the groups. Further, 5-year cumulative incidence for distant recurrence was 18% for both groups.
Researchers observed more grade 3 or worse adverse events in the brachytherapy-chemotherapy group than the pelvic radiation group (187 vs. 32).
“The difference is phenomenally large,” Randall said.
Severe events experienced after treatment were similar between the groups (35 vs. 37).
“Pelvic radiation therapy remains an appropriate, and probably preferable, treatment for high-risk, early-stage endometrial carcinoma,” Randall said. – by Melinda Stevens
Disclosures: Randall is a researcher for NRG Oncology, Gynecology Oncology Group and Uterine Corpus Com. Please see the abstract for a full list of all other authors’ relevant financial disclosures.