In contrast to studies of p16 mRNA, previous studies have reported overexpression of p16 protein to be predictive of improved prognosis in oropharyngeal squamous-cell cancer (Weinberger et al, 2004), vulvar carcinoma (Knopp et al, 2004) and colorectal carcinoma (Zhao et al, 2003; Cui et al, 2004), whereas high levels of p16 protein expression have been associated with shorter event-free survival in prostate cancer (Lee et al, 1999). This evidence concerns the gene CDKN2A and prostate cancer.