Gemcitabine-related thrombocytosis: Does it increase the risk of thrombosis?

Abstract

6091 Background: Gemcitabine is an antimetabolite agent that has demonstrated activity in various solid and hematological malignancies. Although thrombocytopenia is a known side effect, gemcitabine-related thrombocytosis has been uncommonly reported. Chemotherapy increases the risk of thrombo-embolism in patients with cancer. The study aimed to identify the incidence of gemcitabine-related thrombocytosis and to determine whether it has been associated with an increased risk of thrombo-embolism. Methods: Medical records of 175 consecutive adults patients with a malignant disease who received gemcitabine at Saskatoon Cancer Center were reviewed. Patients with history of prior thrombo-embolism or with baseline thrombocytosis were excluded. Fisher’s Exact test was done for statistical analysis. Results: 149 eligible patients with median age of 62 (26–83) and M:F of 1.01:1 were identified. 141 (95%) patients had advanced malignancy and 61 (41%) had received prior chemotherapy. 106 (71%) patients received combination of chemotherapy and 95% of those patients received gemcitabine in combination with a platinum compound. Median number of cycle was 3 (1–8). Median platelets count prior to commencement of gemcitabine was 285 × 109 (44–449). 83 (56%) patients experienced thrombocytopenia whereas 69 (46%) patients experienced thrombocytosis within 3 weeks of treatment with gemcitabine. Median post-gemcitabine platelet count in patients with thrombocytosis was 622 × 109 (457–1385). 15 (10%) patients experienced thrombocytosis with each cycle of gemcitabine. Median duration of thrombocytosis was 2 weeks (0.5−5). 13 (9%) of 149 patients experienced a vascular event (venous, n=9; arterial, n=4) within 6 weeks of treatment with gemcitabine. Median platelet count prior to the vascular event was 268 × 109 (79–669). All except one patient had advanced malignancy and 85% had received combination of chemotherapy. 5 of 69 (7%) patients with thrombocytosis experienced a vascular event compared with 8 of 80 (10%) patients without thrombocytosis (p=0.77). Conclusions: Gemcitabine has been associated with an increased incidence of thrombocytosis. However gemcitabine-related thrombocytosis is a transient phenomenon and has not been associated with an increased risk of a vascular event. No significant financial relationships to disclose.