CDKN2A and adenocarcinoma: A strong and diffuse p16ink4 immunoreactivity (>50% positive cells) was observed in 15 invasive cancers [12 (12/26, 46.2%) anal gland/transitional zone-type adenocarcinoma and 3 (3/48, 6.3%) malignant lesions arising from the colorectal zone] (Fig. 2b).