CDKN2A and colorectal adenocarcinoma: In colorectal adenocarcinoma, a significant association was found between p16 positivity (at least weak immunostaining) and MMR (mismatch repair) status, with a higher percentage of tumors showing positive p16 staining in the MMR-proficient group (56%) than in the MMR-deficient group (27%, p<0.0001).