Usefulness of polyclonal antibodies raised against P65 oncofetal protein in immunohistochemical diagnosis of ductal breast cancer.

Paraffin-embedded infiltrating ductal breast cancer tissue slides (135) were analyzed by immunohistochemistry with the use of rabbit polyclonal anti-P65 oncofetal protein and mouse monoclonal anti-estrogen/progesterone receptor (ER, PR) antibodies. Analysis with anti-P65 antibody revealed the positive cytoplasmic reaction in 83 cases, 98 showed the nucleic reaction and 3 were immunologically negative. Among the analyzed cases 49 revealed both cytoplasmic and nucleic reactions. For the whole group of cancers the correlation was found between ER or PR level and P65 cytoplasmic reaction (r = 0.77 and 0.66, respectively) and low inverse correlation with nucleic localization of P65 protein. The percentage of positive cells with cytoplasmic expression of P65 was significantly higher in more histologically differentiated cancers (grade I and II according to Bloom and Richardson) than in grade III. Opposite tendency was observed for the nucleic expression of P65 protein. The percentage of immunopositive nuclei grew with the advance of the disease and was the highest in poorly-differentiated (grade III) tumors. The tumors with P65 cytoplasmic reaction were mainly small (T1, T2), without metastases to lymph nodes (N0) and distant metastases (M0). The dependence between P65 protein localization and clinical stage of disease (TNM classification) was evaluated statistically. The straight dependence existed between P65 nucleic reaction and tumor size (p = 0.0002), metastases to lymph nodes (p = 0.0032) and distant metastases (p = 0.0006). The obtained results suggest that the transfer of P65 protein from cytoplasm to nuclei of the breast cancer cells is connected with more clinically advanced stages and worse prognosis for the patients.