Occurrence and Management of Thrombocytopenia in Metastatic Colorectal Cancer Patients Receiving Chemotherapy: Secondary Analysis of Data From Prospective Clinical Trials

Introduction Chemotherapy-induced thrombocytopenia (CIT) contributes to treatment dose delay and/or modification, often resulting in poorer survival and disease progression. We explored the incidence and clinical consequences of CIT among metastatic colorectal cancer (mCRC) patients. Materials and Methods Data from two prospective randomized phase 3 trials of mCRC patients receiving either first-line FOLFOX4 (fluorouracil, leucovorin, oxaliplatin) or second-line FOLFIRI (fluorouracil, leucovorin, irinotecan) were analyzed. Thrombocytopenia was defined by platelet count < 100 × 10 9 /L (further categorized by grade) and by recorded adverse events (AEs). Co-occurrence of anemia (hemoglobin < 12 g/dL) and neutropenia (neutrophil count < 2 × 10 9 /L) and clinical consequences of CIT were also evaluated. Results Among 1078 mCRC patients in the FOLFOX4 study, cumulative incidence of CIT based on platelet count was 37% (grade 3, 2%; grade 4, 1%) during an average 8 months' follow-up. Neutropenia or anemia were absent in 44% of CIT episodes; 62% of CIT AEs led to chemotherapy dose delay, change, and/or discontinuation. Among 1067 mCRC patients in the FOLFIRI study, cumulative incidence of CIT based on platelet count was 4% (grade 3, < 1%; grade 4, 0) during an average 4 months' follow-up. Neutropenia or anemia were absent in 22% of CIT episodes; 32% of CIT AEs led to chemotherapy dose delay, change, and/or discontinuation. With both regimens, transfusions and hospitalizations after CIT AEs were rare (< 3%). Conclusion CIT was common among mCRC patients receiving the FOLFOX4 regimen. The most frequent consequence of CIT was a delay in chemotherapy, highlighting the unmet need in CIT management.