Impact of Mitomycin-C-Induced Neutropenia after Hyperthermic Intraperitoneal Chemotherapy with Cytoreductive Surgery in Colorectal Cancer Patients with Peritoneal Carcinomatosis

BACKGROUND: Mitomycin-C (MMC) is the most commonly used chemotherapeutic agent for hyperthermic intraperitoneal chemotherapy (HIPEC) after cytoreductive surgery (CRS). However, MMC has a side effect of myelosuppression. This study aimed to evaluate the clinical manifestations and impact of MMC-induced neutropenia after CRS and HIPEC in colorectal cancer patients. METHODS: A total of 124 colorectal cancer patients who underwent CRS with HIPEC between March 2015 and January 2019 were evaluated. Patients with malignancies of non-colorectal origin, hospital stay longer than 60 days, peritoneal cancer index > 30, and complete cytoreduction score > 2 were excluded. MMC 35 mg/m(2) was administered for 90 min at 41–43 °C. The patients were divided into three groups: no neutropenia, mild neutropenia (grade 1–2), and severe neutropenia (grade 3–4). RESULTS: In total, mild and severe neutropenia occurred in 30 (24.2%) and 48 (38.7%) patients, respectively. Age and body surface area were significantly different among the neutropenia groups. Severe neutropenia developed significantly earlier than mild neutropenia (6.9 days vs. 10.4 days, p < 0.001) and also lasted significantly longer (4.6 days vs. 2.5 days, p = 0.005). The rate of major postoperative complications was significantly higher in the severe neutropenia group than in the no and mild neutropenia groups (8.3% vs. 6.7% vs. 6.5%, p = 0.015) CONCLUSIONS: Severe neutropenia starts earlier and lasts longer than mild neutropenia after CRS and HIPEC using an MMC triple method. The higher rate of major postoperative complications in patients with severe neutropenia highlights the importance of postoperative management during the neutropenia period.