Toxicity after adjuvant therapy for stage III uterine cancer

The optimal adjuvant therapy for stage III endometrial cancer is unknown. Studies have suggested that combination therapy with chemotherapy and radiation is associated with improved survival. We examined early and late-term toxicities associated with chemotherapy (CT), external beam radiotherapy (RT), or combination chemoradiotherapy for stage III uterine cancer.

The SEER-Medicare database was used to identify women age ≥ 65 years with stage III uterine cancer who received adjuvant CT, RT, or chemoradiotherapy from 2000 to 2015. The associations between therapy and early and late-term toxicities identified with billing claims, hospitalizations and emergency department visits were examined using multivariable regression models.

A total of 2185 patients were identified including 574 (26.3%) who received CT, 636 (29.1%) who received RT, and 975 (44.6%) who received chemoradiotherapy. The proportion of patients receiving chemoradiotherapy or CT increased over time. During the first 6 and 12 months of adjuvant therapy, RT was associated with a lower risk of early-term toxicity compared to chemoradiotherapy (aRR = 0.59, 95%CI 0.49-0.70 and aRR = 0.76, 95%CI 0.67-0.86, respectively) while CT shared a similar risk of early toxicities as chemoradiotherapy. CT and RT shared a similar risk of late-term toxicities compared to chemoradiotherapy. CT and RT alone were associated with a higher hazard for overall mortality than chemoradiotherapy (aHR = 1.27, 95% CI 1.10-1.47 and aHR = 1.25, 95% CI 1.08-1.44, respectively).

Chemoradiotherapy is associated with lower mortality compared to single modality therapy and has a similar risk of early and late term toxicities compared to CT, though higher risk of early toxicities compared to RT.