Distribution of CA 125 in adenocarcinomas. An immunohistochemical study of 481 cases.

To determine the distribution of CA 125 in adenocarcinomas, formalin-fixed, paraffin-embedded tissue from 481 cases of adenocarcinoma from a variety of primary sites were studied using a monoclonal antibody to CA 125 (B27.1) and an avidin-biotin immunohistochemical technique. Positive reactivity was most common in adenocarcinomas of the endocervix, ovary, and endometrium (61% to 94%). However, relatively frequent positive reactions also were seen in adenocarcinomas of the pancreas (48%) and bile ducts (56%). Adenocarcinomas of the breast, lung, thyroid, distal esophagus/stomach, and liver (hepatocellular carcinoma) showed positive reactions in 7% to 20% of cases. Staining of rare tumor cells was seen in 2 of 45 colonic adenocarcinomas and in 1 of 61 prostatic adenocarcinomas. No reactivity was seen in the 54 renal cell carcinomas studied. Although CA 125 is most commonly present in gynecologic adenocarcinomas, it is also produced by some adenocarcinomas from many other sites. Immunostaining for CA 125 may be helpful in ruling out renal cell carcinoma in certain clinical settings.