Expression of p53 oncoprotein in different histological types of breast carcinoma.

Based on studies of 263 breast carcinomas, Domagala et al (Am J Pathol 142:669-674, 1993) reported that nuclear p53 accumulation is correlated with a high SBR histological grade in cases of infiltrating ductal carcinoma (IDC). Furthermore, the immunohistochemical expression of p53 was frequent in medullary carcinomas (22/36 cases 61 %), rare in lobular carcinomas (2/47 cases 4.2%), and absent in mucinous carcinomas (0/7 cases). We have confirmed these results. Using frozen specimens and Pab 1801 antiserum on a series of 843 breast cancers (Martinazzi M, et al, Am J Clin Pathol, 1993, 100:213-217), we detected p53 expression in 15.4% of tumors. Expression was significantly correlated with the lack of estrogen (ER) and progesterone receptors (PgR), with a high tumor grade (SBR grading), a high growth fraction as expressed by Ki 67 antibody, and detection of c-erb-2 protein in cases of IDC. Staining for p53 was demonstrated in 5/10 pure medullary carcinomas (50%). No tumors in a series of 8 pure tubular carcinomas, 20 pure mucinous, and 5 pure invasive cribriform carcinomas stained for p53. We also confirmed the observation that p53 is rarely detected in infiltrating lobular carcinomas (ILC) (8/ 174; 4.5%). These cases were frequently ER and PgR negative (4/8 cases). These findings suggest that p53 immunohistochemical reactivity has no relationship to the histological subtyping in cases of ILC.