Understanding Chemotherapy-Induced Thrombocytopenia: Implications for Gastrointestinal Cancer Treatment.

Chemotherapy-induced thrombocytopenia (CIT) is a common yet underrecognized complication of systemic chemotherapy, particularly in gastrointestinal (GI) cancers. Despite progress in targeted and immune-based therapies, platinum-based and fluoropyrimidine regimens, especially oxaliplatin-containing protocols, remain standard in GI cancer treatment and are linked to high rates of CIT. This complication often leads to treatment delays, dose reductions, and elevated bleeding risk. This review provides a comprehensive overview of the pathophysiology, clinical implications, and management strategies of CIT in GI malignancies. CIT arises from several mechanisms: direct cytotoxicity to megakaryocyte progenitors, disruption of the marrow microenvironment, thrombopoietin dysregulation, and immune-mediated platelet destruction. Platinum agents, antimetabolites, and immune checkpoint inhibitors can contribute to these effects. Oxaliplatin-induced CIT may occur acutely via immune mechanisms or chronically through marrow suppression. CIT affects 20-25% of solid tumor patients, with highest rates in those receiving gemcitabine (64%), carboplatin (58%), and oxaliplatin (50%). Within GI cancer regimens, FOLFOXIRI and S-1 plus oxaliplatin show higher CIT incidence compared to FOLFIRI and CAPIRI. Thrombocytopenia is graded by severity, from mild (Grade 1-2) to severe (Grade 3-4), and often necessitates treatment adjustments, transfusions, or supportive therapies. Current strategies include chemotherapy dose modification, platelet transfusion, and thrombopoietin receptor agonists (TPO-RAs) like romiplostim and eltrombopag. While platelet transfusions help in acute settings, TPO-RAs may preserve dose intensity and reduce bleeding. Emerging agents targeting megakaryopoiesis and marrow protection offer promising avenues for long-term management.