RB growth control evasion in lung cancer

We evaluated the expression of pRb by immunohistochemistry in 98 lung cancer specimens already characterized for their p16 and cyclin D1 status. We found the absence of pRb expression to be dependent upon the histological type, being more frequent in SCLCs than in NSCLCs (p<.00005). On the other hand, we failed to find any correlation between the expression of pRb and p16. In addition, we found a positive correlation between the expression of pRb and cyclin D1 (p=.0001). Therefore, we hypothesize that pRb growth control may be overcome by two different mechanisms in lung carcinogenesis: loss ofpRb expression or overexpression of cyclin D1.