AN IMMUNOHISTOCHEMICAL SURVEY OF PS2 EXPRESSION IN HUMAN EPITHELIAL CANCERS

The oestrogen-inducible pS2 protein isolated from human breast-cancer cells appears to have prognostic significance in breast-cancer patients. Using both monoclonal and polyclonal pS2 anti-sera, we have carried out an immunocytochemical survey of 9 epithelial cancers. Some degree of specific tumour staining was observed in 4 tissues, the extent varying greatly between specimens. Most (11/13) of the colorectal cancers showed immunoreactivity, as did 4/5 pancreatic carcinomas. In some of these cases, patchy staining was also observed in adjacent non-tumour cells. Two bronchio-alveolar carcinomas showed positivity, but 5 poorly differentiated adenocarcinomas of the lung did not. In the ovary, staining was observed in 3/3 mucinous cystadenocarcinomas but only in 1/8 of the serous type. No reactivity was seen in specimens of salivary gland, kidney, liver, prostate or uterus. This pilot study indicates that pS2 may be a useful marker of adenocarcinomas in human neoplasms apart from those in the breast, and suggests that more extensive surveys might be worthwhile.