Obesity and pathological features of tumour aggressiveness and lymph node staging in colon cancer: a multicentre propensity score-matched study

Abstract Aim To investigate whether obesity (BMI ≥ 30) influences pathological markers of tumour aggressiveness and lymph node staging quality (≥ 12 retrieved nodes) in patients undergoing elective colon cancer surgery. Methods This multicentre retrospective cohort study included adults undergoing elective surgery for colon adenocarcinoma at three tertiary referral centres. Patients with rectal cancer, emergency surgery, metastatic disease, neoadjuvant therapy, or incomplete data were excluded. Obesity was defined as a BMI ≥ 30 kg/m². Clinical, surgical, and pathological data were collected from prospectively maintained databases. Associations between obesity and study outcomes were evaluated using multivariable logistic regression adjusted for age, sex, ASA score, tumour location, T stage, and MSI status. Results A total of 126 patients undergoing elective surgery for colon adenocarcinoma were included, of whom 42 (33.3%) BMI > 30. Obesity was not associated with lymphovascular invasion, tumour necrosis, or high-grade histology. In contrast, obesity independently predicted both perineural invasion (OR 3.59, 95%CI 1.16–11.50; p = 0.011) and peritumoral deposits (OR 2.82, 95%CI 1.03–7.69; p = 0.032). Higher T stage correlated with aggressive pathological features, whereas MSI status showed a protective effect. Regarding lymph node assessment, the proportion of patients with ≥ 12 retrieved nodes was high and similar between obese and non-obese patients (88.1% vs. 83.3%, p = 0.48). Obesity was not independently associated with adequate lymph node staging (OR 1.48, 95%CI 0.50–4.43; p = 0.48). Conclusion Obesity did not compromise nodal staging or most tumour aggressiveness markers, but its association with perineural invasion and tumour deposits highlights a potentially distinct, clinically relevant tumour biology.