Relationship Between the Product of Pre‐Treatment Neutrophil and Monocyte Counts and Clinical Outcomes in Rectal Cancer With Suspected Lateral Lymph Node Metastasis

Aim A novel systemic inflammatory response marker, the neutrophil × monocyte value (NM value), has been identified as a negative predictive factor for responses to chemoradiotherapy in rectal cancer. However, the clinical implications of the NM value remain unknown. Methods This study reviewed 352 patients with rectal cancer who received preoperative chemoradiotherapy between 2003 and 2023. The cut‐off value for the pre‐treatment NM value was established at the median. A pre‐treatment size of lateral lymph node (LLN) ≥ 8 mm was defined as clinical LLN metastasis. The prognostic significance of the NM value was evaluated. Results The cut‐off NM value was 1 100 000; 179 patients had an NM value ≥ 1 100 000. Ninety‐nine patients had LLN ≥ 8 mm. Disease‐free survival (DFS) was significantly shorter in patients with an NM value ≥ 1 100 000 than in those with an NM value < 1 100 000. DFS and overall survival (OS) were shorter in patients with LLN ≥ 8 mm than in those with LLN < 8 mm. The LLN size and NM value were identified as independent prognostic factors for DFS (LLN size—hazard ratio (HR): 1.51, p = 0.04, NM value—HR: 1.53, p = 0.04). Patients with LLN ≥ 8 mm and an NM value ≥ 1 100 000 had the poorest prognosis among the populations compared by the combination of LLN size and NM value. Conclusions The pre‐treatment NM value is an independent prognostic factor associated with DFS. In patients with LLN ≥ 8 mm, a high NM value may be a significant indicator of a poor prognosis.