Immunoradiometric assay (IRMA) using monoclonal antibody for colon cancer cell surface antigen (CA19-9) was compared with carcinoembryonic antigen (CEA) with regard to sensitivity and specificity in 730 patients. In the 341 patients who had no evidence of malignant disease, CA19-9 levels ranged between 4. 5 to 49 U/ml. Specificity of CA19-9 at a cutoff of 20 U/ml was similar to that of CEA at a cutoff of 5.0 ng/ml; CA19-9 was more sensitive than CEA in pancreatic cancer, whereas CEA was more sensitive than CA19-9 in breast, colon, and gastric cancer. Of 17 patients with pancreatic cancer, 13 had elevated levels of CA19-9 (sensitivity, 76%). whereas only 8 had elevated levels of CEA (sensitivity, 47%) and 15 had elevated levels of either CEA or CA19-9 (sensitivity, 88%). These findings suggest that, like CEA, CA19-9 is detectable in nonmalignant diseases and is not specific for gastrointestinal tumors, and has higher sensitivity than CEA only in pancreatic cancer. However, further prospective studies are required to verify its value in the diagnosis and management of pancreatic cancer. Cancer 56977-283, 1985. LTHOUGH carcinoembryonic antigen (CEA) has A been the most widely studied'-3 and used marker in human cancer, it lacks the specificity and sensitivity required for early detection of malignan~y.~ Clinically, it is used only as an indicator of recurrence or as a monitor of therapy in known cancer More recently, hybridoma technology* has renewed interest in more specific tumor markers. Koprowski et al. developed a monoclonal antibody to colon cancer cell surface antigen in 19799 and later showed that this antibody reacted with sialylated lacto-N-fuco-pentoase 11. l o In early clinical studies, this same antibody has been found to be both highly sensitive and specific in identifying gastrointestinal adenocarcinoma.'1*'2 A radiometric assay using this antibody has been made available for inves-tigational purposes (along with the necessary reagents) by Centocor (Philadelphia).'' In this report we present our results with this assay, including comparison with CEA, in patients with malignant and nonmalignant diseases. Materials and Methods Immimoradiometric Assay for CA19-9 Details of the CA19-9 assay have been described previously. Briefly, antibody coated beads were incu-bated with standards and unknowns (100 pl) in 25 well reaction trays for 3 hours at 37°C. The beads were then washed and 200 ~l of radiolabeled iodine 125 ('251) anti-CA19-9 (approximately 100,OOO cpm) was added to each bead. The beads were incubated for 3 hours at room temperature, followed by aspiration and washing, after which they were transferred into 12 X 75 mm tubes and counted in a gamma counter. The lowest 277

No abstract

; SHARON SLAUGHTER, MT(ASCP)I • The authors used laser immunonephelometry to measure cerebrospinal fluid and serum immunoglobulin G and albumin in patients with multiple sclerosis and other neurological diseases known to cause increased cerebrospinal fluid immunoglobulin G. The Wilcoxon rank-sum test showed that for four commonly used formulas (Tourtellotte's, Schuller's, the immunoglobulin G index, and immunoglobulin G/albumin) the definite multiple sclerosis group had significantly higher values of these variables than did the normal group or the groups with possible multiple sclerosis, other neurological diseases, or nonimmunological other neurological diseases. McNemar's test of symmetry showed that Tourtellotte's formula was more sensitive than other formulas and that Schuller's formula was slightly more specific than other formulas. Receiver operating characteristic curves showed that there was little difference among the formulas.