Effect of time interval between surgery and the initiation of adjuvant therapy on the oncologic outcomes of early-stage endometrial cancer.

Objective: To identify the impact of time interval between surgery and initial adjuvant radiotherapy on oncologic outcomes in early-stage endometrial cancer.

Methods: This retrospective cohort study included patients with stage I/II endometrial cancer who underwent surgical staging and adjuvant therapy at Songklanagarind Hospital from January 1, 2007, to December 31, 2017. Patients were categorized into two groups: TI <6 weeks and TI ≥6 weeks. The effects of TI and clinicopathological factors on recurrence-free survival (RFS) and overall survival (OS) were analyzed using Cox proportional-hazards regression.

Results: In total, 177 patients were enrolled, with 52% receiving adjuvant radiotherapy at <6 weeks (overall median TI 5.7 weeks). The recurrence and death rates were 13% and 10.2%, respectively. The median follow-up time was 46.6 months. The overall 3-year RFS and OS rates were 88.2% and 85.2%, respectively. The TI significantly affected the 3-year RFS (94.4% vs 81.2%; P = 0.008) and 3-year OS (95.5% vs 83.2%; P = 0.012) in patients with TI <6 and ≥6 weeks, respectively. In multivariate analysis, the depth of myometrial invasion (MI), presence of lymphovascular space invasion, and TI were independent prognostic factors for both RFS and OS. Delaying the TI (≥6 weeks) was significantly associated with a worse RFS (hazard ratio [HR] 3.70; 95% confidence interval [CI]: 1.34-10.22; P = 0.012) and an inferior OS (HR 3.80; 95% CI: 1.23-11.69; P = 0.02).

Conclusion: A delay in the TI between surgery and the initiation of adjuvant radiotherapy of ≥6 weeks negatively affected the oncologic outcomes in early-stage endometrial cancer.