Neutropenia in colorectal cancer treated with oxaliplatin-based hyperthermic intraperitoneal chemotherapy: An observational cohort study.

BACKGROUND The implications of neutropenia after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) treatment have never been investigated. AIM To evaluate the occurrence of neutropenia and its effect on the risk of increased Clavien-Dindo morbidity as well as its effect on overall or disease-free survival. METHODS All patients with colorectal peritoneal metastases (1996-2015) completing cytoreductive surgery and oxaliplatin-based HIPEC treatment from a bi-institutional database (Uppsala and Sydney) were included in the study. Clavien-Dindo grade 3-4 morbidity differences between the neutropenia group vs non-neutropenia group were calculated and Kaplan-Meier curves with log rank test were rendered. Univariate and multivariable Cox regression models for disease-free survival were implemented. RESULTS Two hundred and forty-six patients were identified - 32 postoperative any-grade neutropenia patients and 214 non-neutropenia patients. The neutropenia group had more combination oxaliplatin + irinotecan treatment than the non-neutropenia group (66% vs 13%, P = 0.0001). The neutropenia group was not associated with increased Clavien-Dindo grade 3-4 morbidity. Median overall survival was 53 mo vs 37 mo for the neutropenia and non-neutropenia group, P = 0.07. Median disease-free survival was 16 mo vs 11 mo, respectively, P = 0.02. Neutropenia was an independent prognostic factor for disease-free survival with hazard ratio: 0.58, 95% confidence interval: 0.36-0.95, P = 0.03. CONCLUSION 13% of patients developed neutropenia which was not associated with increased Clavien-Dindo grade 3-4 morbidity. Neutropenia was an independent positive prognostic factor for disease-free survival and was associated with more intense HIPEC treatment. This is in direct contrast to the current paradigm of decreasing the treatment intensity.