Less-favourable prognosis for low-risk endometrial cancer patients with a discordant pre- versus post-operative risk stratification.

Background: Pre-operative risk stratification based on endometrial sampling determines the extent of surgery for endometrial cancer (EC). We investigated the concordance of pre- and post-operative risk stratifications and the impact of discordance on survival.

Methods: Patients diagnosed with EC within the first 6 months of the years 2005-2014 were selected from the Netherlands Cancer Registry (N = 7875). Pre- and post-operative risk stratifications were determined based on grade and/or histological subtype for 3784 eligible patients.

Results: A discordant risk stratification was found in 10% of patients: 4% (N = 155) had high pre- and low post-operative risk and 6% (N = 215) had low pre- and high post-operative risk. Overall survival of patients with high pre- and low post-operative risk was less favourable compared to those with a concordant low risk (80% versus 89%, p = 0.002). This difference remained significant when correcting for age, stage, surgical staging and adjuvant therapy (hazard ratio 1.80, 95% confidence interval 1.28-2.53, p = 0.001). Survival of patients with low pre- and high post-operative risk did not differ from those with a concordant high risk (64% versus 62%, p = 0.295).

Conclusion: Patients with high pre- and low post-operative risk have a less favourable prognosis compared to patients with a concordant low risk. Pre-operative risk stratifications contain independent prognostic information and should be incorporated into clinical decision-making.