Adjuvant therapy does not extend survival in high-risk endometrial cancer
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Postoperative systemic or radiation therapy did not extend survival for women with high-risk stage I endometrial cancer, according to results presented at the virtual Society of Gynecologic Oncology Annual Meeting on Women’s Cancer.
Researchers reported no benefit in OS or cancer-specific survival with either treatment modality. In addition, longer duration of postoperative chemotherapy did not affect survival outcomes, results of the multicenter, population-based study showed.
“This is one of the largest databases of this particular group of patients with endometrial cancer,” Rachelle Findley, BSc Pharm, MD, FRCSC, gynecologic oncology fellow at University of Calgary, said during her presentation. “A large prospective study would be needed to confirm our results from our retrospective data.”
Endometrial cancer is the most common gynecologic malignancy among Western women.
Surgical resection is a standard treatment; however, the optimal adjuvant treatment and the survival benefits it provides for women with stage I disease have not been clearly defined.
Findley and colleagues compared the patterns and survival outcomes of postoperative treatment for this patient population.
Their analysis included 414 consecutive women (age range, 33-91 years) diagnosed with high-risk stage I disease between 2000 and 2010 at eight cancer centers in Canada.
The majority of women (70.3%) had stage IA disease. Most (85.5%) had myoinvasive nonendometrioid histology, whereas 14.5% had grade 3 endometroid histology. The percentage of patients who died was comparable between the endometroid and nonendometrioid groups (15.7% vs. 14%) despite the significant differences in frequencies with which they occurred, Findley said.
Investigators observed heterogeneity among the centers with regard to extent of surgical staging.
More than half (58.9%) of women underwent pelvic lymphadenectomy; 8% underwent para-aortic lymphadenectomy. About one-third (34.8%) of women had lymphovascular space invasion.
Approximately one-quarter (24%) received adjuvant chemotherapy and more than half (56%) received adjuvant radiotherapy.
Results showed adjuvant chemotherapy did not improve median OS (8.52 years vs. 7.48 years; HR = 0.7; 95% CI, 0.46-1.14) or disease-specific survival (not reached in either group; HR = 1.06; 95% CI, 0.61-1.85).
However, women who underwent chemotherapy achieved significantly longer median RFS (8.52 years vs. 6.92 years; HR = 0.61; 95% CI, 0.39-0.95).
Adjuvant radiation therapy did not significantly improve OS (HR = 0.9; 95% CI, 0.63-1.2), disease-specific survival (HR = 1.11; 95% CI, 0.68-1.82) or RFS (HR = 0.73; 95% CI, 0.51-1.02). Longer duration of chemotherapy — five or six cycles vs. four or fewer — did not affect any of the survival outcomes.
Women aged 55 years and older, those who had stage IB disease, and those with higher disease grade or lymphovascular space invasion appeared more likely to develop recurrence and had poorer survival, according to researchers.
Findley and colleagues acknowledged limitations to their study, including the potential for surgical understaging and patient heterogeneity, as well as confounders in patient selection.
“When we look at stage IB, grade III endometrioid carcinoma, this remains a bit of a black box,” Findley said. “Unfortunately, the numbers in our group were small, but in that small group, the rate of death was equivalent to nonendometrioid high-risk endometrial cancer despite representing a fraction of the group. This indicates we likely don’t fully understand management of this subgroup, and perhaps molecular testing will provide the answer.”
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Findley R, et al. Abstract 10533. Presented at: Society of Gynecologic Oncology Annual Meeting on Women’s Cancer (virtual meeting); March 19-25, 2021.
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