Relation between retinoblastoma and p53 proteins in human papilloma viruses 16/18 positive and negative cancers of the uterine cervix

Aim - To ascertain the extent of retinoblastoma protein (pRB) expression in comparison to p53 protein and human papilloma viruses (HPV) 16/18 status in cervical carcinomas. Methods - Fifty cases of invasive cervical carcinoma were HPV typed for genotypes 16 and 18 using consensus primers by polymerase chain reaction (PCR). Immunohistochemistry for pRB and p53 was done on formalin fixed tissue using microwave antigen retrieval and commercially available antibodies. Results - Forty five cases were squamous carcinomas, three were adenocarcinomas, and two were adenosquamous carcinomas. Thirty one cases were HPV 16 positive and one was HPV 18. Sixteen cases showed +4 pRB expression and a further 11 were +3 positive. Seven cases were negative. Only five cases (10%) showed +4 p53 immunostaining, while seven were negative and 15 were +1. Of the 16 pRB +4 positive cases, one was negative for p53 and a further seven were +1 positive. This inverse pattern of staining between pRB and p53 had a p value of <0.001. No correlation was observed between HPV 16/18 status and p53 and/or PRE staining. Conclusions - pRB is expressed in the majority of cases of cervical cancer (86%), with more than 75% (+4) of the tumour cell population being positive in 16 cases (32%). There appears to be a general inverse pattern of staining between pRB (high) and p53 (low) in cervical cancer. The expression of both pRB and p53 proteins is independent of the HPV 16/18 status of the tumour.