Abstract 3404: Thrombocytosis and epithelial ovarian cancer survival: relevant time frame of platelet count measurement and diagnostic threshold for thrombocytosis

INTRODUCTION: Ovarian cancer is rapidly progressive and lethal disease. Thrombocytosis has been associated with poor prognosis; mechanisms underlying this association include paracrine signaling between platelets and cancer cells, resulting in tumor cell proliferation. However, the relevant timing of platelet measurement in relation to diagnostic operation and a threshold to define thrombocytosis as a prognostic indicator have not been evaluated. METHODS: Tumor Registry confirmed epithelial ovarian and fallopian tube cancer cases with pre-diagnosis platelet counts were identified from the Synthetic Derivative, a de-identified mirror of electronic medical records from the Vanderbilt University Medical Center. Thrombocytosis was defined with two thresholds: platelet count greater than 400 or 450 × 109/L. The relevant time frame of platelet measurement was evaluated within 5 time intervals: on the date of diagnosis, and 1, 2, 4, and 8 weeks before and including the date of diagnosis. Prognostic significance was evaluated using Cox proportional hazards regression to calculate hazard ratios (HR) and confidence intervals (CI); adjustment included age, stage, grade, and histologic subtype of disease. RESULTS: Measured platelet values were available for 136, 241, 280, 297, and 304 cases within the five time intervals. The prevalence of thrombocytosis was 31.6, 39.4, 38.2, 38.1, and 37.5% for 400 × 109/L, and 19.9, 26.1, 25.7, 24.9, and 25.0% for 450 × 109/L across the five intervals, respectively. Thrombocytosis was significantly associated with higher stage and grade, regardless of threshold used. In both unadjusted and multivariable adjusted analysis, thrombocytosis was significantly associated with worse survival. Associations were similar across thresholds and time frames, but were generally larger on the date of diagnosis (HR(400): 1.96, 95% CI 1.23-3.13; HR(450): 1.90, 95% CI: 1.12-3.23), and smaller as time to diagnosis increased up to 8 weeks (HR(400): 1.54, 95% CI: 1.14-2.09; HR(450): 1.55, 95% CI: 1.11-2.15). CONCLUSIONS: Depending upon the threshold used and the timing of measurement, thrombocytosis was identified in 20-40% of epithelial ovarian cancer cases. Regardless of threshold or timing, preoperative thrombocytosis was associated with more aggressive disease characteristics and was an independent negative prognostic factor. These preliminary results support use of a lower thrombocytosis threshold and indicate that platelet count measurements collected up to 8 week preoperatively may be used to inform ovarian cancer prognosis. Citation Format: Gabriella D. Cozzi, Jacob M. Samuel, Jason T. Fromal, Spencer Keene, Marta A. Crispens, Dineo Khabele, Alicia C. Beeghly-Fadiel. Thrombocytosis and epithelial ovarian cancer survival: relevant time frame of platelet count measurement and diagnostic threshold for thrombocytosis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3404.