SHH and skin basal cell carcinoma: After mutual correction of the two genes SHH and SFRP5 by multivariate logistic regression, odds ratios for individual genes were still larger than 1 (O.R. 1.42 (P = 0.304) and 2.01 (P = 0.032) respectively), suggesting that methylation of SFRP5 is significantly associated with the occurrence of BCC.