To explore whether melanosis coli (MC) and is associated with laterally spreading tumors (LST), and the cancer risk.

We conducted a retrospective study involving patients diagnosed with melanosis coli through colonoscopy at our hospital between 2018 and 2022, and propensity matching scores (PSM) were performed. Age and gender were used as matching variables to perform 1∶2 nearest-neighbor matching between the MC group and the control group. A total of 361 MC patients and 722 controls were enrolled in the study, and our analysis sought to examine the relationship between LST and MC.

The LST detection rates in the MC and control groups were 10.7% and 6.2%, respectively (P=0.040), and further binary logistic regression analysis showed that MC was significantly correlated with an increased LST detection rate (OR: 1.487, 95%CI: 1.096-2.012, P=0.010). In addition, the rate of LST malignancy was increased in MC (P=0.026), and binary logistic regression analysis demonstrated that MC was a risk factor for LST malignancy (OR: 1.825, 95%CI: 1.276-2.611, P=0.001). LST detection was correlated with the distribution (P=0.005), and grade (P=0.045) of MC.

The detection rate of LST is higher in MC compared to the control group, and the incidence of LST malignancy is higher in MC.