Detection of a new embryonic antigen (ESA-10) in the blood of patients with cancer: preliminary results in the United States.

ESA-10 is an embryonic antigen expressed by tumor cells. A method to detect the antigen in the blood based on alterations in the erythrocyte sedimentation rate that occur when antiserum to ESA-10 is bound to the antigen in blood was devised and used here to determine the sensitivity and predictive value of the test in patients with biopsy proven non-hematologic malignancies, and in normal control subjects. The test was positive in 22 of 24 cancer patients tested, and negative in 30 of 35 control subjects. Of the five positive control subjects, one female had recently given birth and was lactating. Another control subject was recently diagnosed with prostate cancer, just months after having participated in this study. Therefore, this tumor marker test (Turtest(®)) had a sensitivity of 91.7% and a positive predictive value of 81.5% in patients with biopsy proven cancer, and a specificity and negative predictive value in control subjects of 88.2 and 93.8%, respectively, if the control subject who subsequently developed prostate cancer is removed from the control group. Therefore, this simple test has potential as a clinically useful tumor marker with sensitivity and specificity equal to or greater than other commercially available tumor markers and should be explored further in larger studies.