Chemotherapy response rates among patients with endometrial cancer who have elevated serum platelets

Objective This retrospective study evaluates the influence of serum platelet count on chemotherapy response rates among women with endometrial cancer. Methods From 3 separate cancer centers, a total of 318 patients with endometrial cancer who received postoperative chemotherapy between June 1999 and October 2009 were retrospectively identified. Endometrioid, serous, clear cell, and carcinosarcoma histologies were included. Patients were classified as having an elevated platelet count if their serum platelet count was greater than 400 × 10⁹/L at the time of initial diagnosis. Primary outcome was chemotherapy response, classified as either complete or partial/refractory. Secondary outcomes were disease-free and disease-specific survival. χ² Test and Student t test were performed as appropriate. Kaplan-Meier curves and Cox proportional hazards models were used to assess serum platelet effect on survival. Results There were 125 deaths, 76 recurrences, and 48 disease progressions. Of the total group, 53 (16.7%) were categorized as having an elevated platelet count. An elevated platelet count was associated with a lower chemotherapy response rate in univariate analysis (hazard ratio [HR], 2.8; 95% 95% confidence interval [CI], 1.46-5.38; P < 0.01). Multivariate analysis showed elevated platelets to be independently associated with decreased disease-free survival (HR, 2.24; 95% CI, 1.26-3.98; P < 0.01) but not disease-specific survival (HR, 1.03; 95% CI, 0.56-1.88, P = 0.93). Conclusions Patients with endometrial cancer who have an elevated serum platelet count greater than 400 × 10⁹/L may have lower chemotherapy response rates and are at increased risk for recurrence when compared with patients with a count within the reference range.