Prognostic impact of high p16/cyclin D1 index in breast cancer

Proteins p16 and cyclin D1 (CCND1) are known to tightly regulate the G1/S transition during the cell cycle, but their role in breast cancer development and progression is not clear. We investigated 224 cases of breast cancer from the Kangbuk Samsung Medical Center between 2000-2005. Expression levels of p16 and CCND1 were assessed by tissue microarray-based immunohistochemistry. A p16/CCND1 index was divided into low- and high-expression groups using receiver operating characteristic curves. The p16/CCND1 index was significantly different across molecular subtypes and a high p16/CCND1 index was statistically correlated with survival rates. This p16/CCND1 index may be an indicator of poor patient outcome and thus, represents a potential therapeutic target.