Retinoblastoma and p16 proteins in mammary carcinoma: Their relationship to cyclin D1 and histopathological parameters

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Abstract
The cell cycle‐associated retinoblastoma protein (pRb) and p16 protein were demonstrated using immuno‐histochemistry on paraffin sections from 192 cases of invasive breast carcinoma. Abnormal expression of pRb was defined as negative staining and was seen in 17% of tumours. Such abnormal expression was significantly more frequent in tumours with negative oestrogen receptor (ER) status. There was also a trend for tumours which were negative for pRb to be grade III ductal carcinomas. There was no association between p16 staining and any histopathological parameter, though, surprisingly, log‐rank analysis showed that strong staining was associated with a poor outcome. There was a significant inverse relationship between pRb and p16 expression and a significant positive association between pRb and cyclin D1. In a Cox multivariate analysis, which included cyclin D1, neither pRb nor p16 was an independent predictor of patient outcome. Int. J. Cancer (Pred. Oncol.) 79:71–75, 1998.