Risk Factors for Positive Peritoneal Lavage Cytology in Stage I to III Colon Cancer: A Prospective Observational...

Positive peritoneal lavage cytology (PLC) in non-metastatic colon cancer is a marker for a higher likelihood of future peritoneal recurrence and poorer survival. Any association between PLC and the tumour site (laterality), stage, and other pathological variables is debated. Our study aimed to find any relationship between the positive PLC, laterality, stage and other pathological parameters in resectable non-metastatic colon cancer. We performed a prospective, observational study on all consecutive patients with stage I-III adenocarcinoma of the colon undergoing upfront curative resection at our centre from March 2021 to February 2023. Patients previously treated with chemotherapy, previous abdominal surgery, colon cancer as a second primary, intraperitoneal tumour rupture, and ascites were excluded from the study. PLC was performed using pre-standardised surgical and pathological methods determined by the research team. Among the 119 eligible patients, positive PLC was found in 15 (23.08%) of those with right-sided disease (n = 65) and 6 (11.11%) of those with left-sided disease (n = 54) (p = 0.57). On univariate analysis, positive PLC was found to be associated with higher N-status (p = 0.004), higher overall stage (p = 0.003), presence of perineural invasion (PNI) (p = 0.003), extranodal extension (ENE) (p = 0.004), signet ring cell type morphology (p = 0.002), and pre-operative CEA level > 5 ng/dl (p = 0.003). Multivariate analysis revealed an association between positive PLC and higher-grade disease, N status, and stage IIIC disease. Positive PLC status in resectable colon cancer did not correlate with the laterality of the primary tumour but was associated with a higher nodal burden, overall stage, presence of PNI, ENE, presence of signet ring cells, and a preoperative CEA level > 5 ng/ml. Further studies and follow-up are needed to establish their value in detecting future peritoneal recurrence.