APC and bladder transitional cell carcinoma: As DNA methylation gained a lot of attention for being considered a potential non-invasive biomarker for BLCA, it has been demonstrated by numerous reports that DNA aberrant methylation is not only present in BLCA individuals but its risk increases in smokers [30], which highlights our findings in terms of the correlation between smoking status and APC promoter gene methylation (p-value <0.001).