The bevacizumab plus oxaliplatin-based chemotherapy regimen is more suitable for metastatic colorectal cancer patients with a history of schistosomiasis: a clinical retrospective analysis.

Background: The basic platelet counts of schistosomiasis patients are low. If it does not meet the requirements for chemotherapy, the patient's treatment will not be carried out, which directly affects their prognosis. Therefore the impact of treatment on platelet counts is critically important. The effects of bevacizumab plus oxaliplatin-based chemotherapy and bevacizumab plus irinotecan-based chemotherapy regimens on platelets are different but have not been determined. In order to find a more suitable plan for metastatic colorectal cancer (mCRC) patients with a history of schistosomiasis, we conducted a retrospective analysis of mCRC patients and evaluated the impact of bevacizumab on their platelets.

Methods: The medical records of all mCRC patients with a history of schistosomiasis who received oxaliplatin-based chemotherapy or irinotecan-based chemotherapy as first-line treatment for no less than 4 cycles, with or without bevacizumab from September 1, 2017, to June 30, 2019, in Kunshan Hospital were reviewed. Six-month cumulative incidence rates of splenomegaly and thrombocytopenia of chemotherapy with and without bevacizumab groups, oxaliplatin-based chemotherapy with and without bevacizumab groups, irinotecan-based chemotherapy with and without bevacizumab groups were compared from the first cycle until the completion of chemotherapy using Kaplan-Meier analysis and Log-rank test.

Results: Evaluable splenic enlargement and thrombocytopenia results were obtained from 153 mCRC patients. The 6-month cumulative incidence rates of splenomegaly (23.3% 55%; P=0.01) and that of thrombocytopenia (43.8% 57.5%; P=0.40) were lower in the bevacizumab group than the non-bevacizumab group, however there were no statistical differences for the rates of thrombocytopenia. For patients treated with oxaliplatin, the rates of splenomegaly (19.5% 66.7%; P=0.01) and thrombocytopenia (31.7% 77.2%; P=0.02) were lower in the bevacizumab-treated cohort than that in the non-bevacizumab cohort. When stratified for irinotecan, there were no statistical differences in the frequency of splenomegaly between the two groups. However, the rates of thrombocytopenia were higher in the bevacizumab-treated cohort than that in the non-bevacizumab cohort (59.4% 8.7%; P=0.01).

Conclusions: The bevacizumab plus oxaliplatin-based chemotherapy regimen is safer for mCRC patients with a history of schistosomiasis, especially for patients with a lower platelet count.