High L1CAM expression was associated with invasive tumor growth (pTa vs. pT2–4) in urothelial carcinoma of the bladder (p < 0.0001) and with mismatch repair protein deficiency (p = 0.0064) and left-sided tumor location (p = 0.0104) in colorectal adenocarcinoma. Here, L1CAM is linked to bladder transitional cell carcinoma.