Low frequency and low level of elevation of serum CA 72-4 in human carcinomas in comparison with established tumor markers.

We evaluated a new circulating tumor marker, CA 72-4, by comparing its frequency of appearance and level of elevation with other established tumor markers in serial serum specimens from patients with various carcinomas. We found that CA 72-4, though highly expressed and widely found in various tumor tissues, is present at low concentration and frequency in the serum. In breast, colon, ovarian, and pancreatic carcinomas, only 21%, 30.9%, 16%, and 26.5% of specimens, respectively, showed elevated CA 72-4. When elevated, the level of elevation was also low, much lower than that of the dominant markers. Poor response of CA 72-4 to therapy was especially noticeable in serial specimens. In most cases, the CA 72-4 remained normal for the entire series while other markers remained at elevated levels. However, changes of the level of CA 72-4 usually paralleled those of other markers but at a much lower concentration. Simultaneous measurement of CA 72-4 and CA 19-9 appears useful to differentiate colorectal from pancreatic carcinomas when they all contained elevated levels of CA 19-9. There was a much higher ratio of CA 72-4 to CA 19-9 with colon than with pancreatic and other carcinomas (247 +/- 524 vs. 4.7 +/- 6.8).