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.