Risk Factors for Thrombocytopenia Induced by Capecitabine Plus Oxaliplatin Therapy in Patients With Colorectal Cancer

Capecitabine plus oxaliplatin (CapeOX) therapy is used as an adjuvant chemotherapy regimen for patients with colorectal cancer (CRC). Although oxaliplatin induces thrombocytopenia, the risk factors for thrombocytopenia in oxaliplatin-treated patients with CRC are not well established. We aimed to investigate the risk factors for thrombocytopenia in CapeOX-treated patients with CRC. In addition, we evaluated platelet counts and non-invasive liver fibrosis indices, specifically the aspartate aminotransferase-to-platelet ratio index (APRI) and the fibrosis-4 index (FIB-4), during CapeOX therapy in these patients.

Between July 2017 and June 2020, we enrolled CapeOX-treated patients with high-risk stage II or stage III CRC at seven hospitals collaborating with the Division of Oncology, Aichi Prefectural Society of Hospital Pharmacists (Aichi prefecture, Japan). In this retrospective study, we investigated patients' backgrounds, laboratory data, concomitant medications, number of cycles of CapeOX and oxaliplatin, cumulative dose of oxaliplatin, and administration period. The cut-off values were calculated using receiver operating characteristic analysis of platelet counts and APRI and FIB-4 scores.

Fifty-five patients without thrombocytopenia and 44 patients with thrombocytopenia were enrolled. During CapeOX therapy, the thrombocytopenia group showed a significant decrease in platelet count and a significant increase in APRI and FIB-4 scores compared to the non-thrombocytopenia group. Baseline albumin level ≤3.5 g/dl and platelet count ≤238×10³/μl were independently associated with ≥grade 2 thrombocytopenia in CapeOX-treated patients.

Baseline albumin level and platelet count may be useful for predicting thrombocytopenia in CapeOX-treated patients with high-risk stage II or stage III CRC.