Wj. Allard et al., NONSPECIFIC CROSS-REACTING ANTIGEN 50 90 IS ELEVATED IN PATIENTS WITHBREAST, LUNG, AND COLON-CANCER/, Cancer research, 54(5), 1994, pp. 1227-1234
A total of 22 genes have been identified in the carcinoembryonic antig
en (CEA) gene family The protein products of this family are highly ho
mologous and include CEA, biliary glycoprotein, nonspecific cross-reac
ting antigen 50/90 (NCA 50/90), NCA 95, and pregnancy-specific beta-gl
ycoprotein. We used a monoclonal antibody with high affinity to develo
p a specific enzyme-linked immunosorbent assay (ELISA) method for NCA
50/90 in serum and plasma. Our calibrators were based on affinity-puri
fied recombinant protein from a Baculovirus expression system. No sign
ificant reactivity with purified CEA, recombinant NCA 95, or recombina
nt biliary glycoprotein was found by Western blot analysis or in the E
LISA method. Only 1 of 15 sera from pregnant women (chorionic gonadotr
opin > 1000 ng/ml) was positive in the NCA 50/90 ELISA, suggesting tha
t this method does not detect pregnancy-specific glycoprotein. A cutof
f value of 18 ng/ml was established based on the 95% value of serum an
d plasma from 147 healthy volunteers. Only 3 of 31 serum and plasma sa
mples from patients with clinically inactive breast cancer were elevat
ed above the cutoff value, but 44% of 136 samples from patients with c
linically active breast cancer were positive. NCA 50/90 measurements w
ere elevated in 7 of 25 patients with active breast cancer whose CEA a
nd CA 15-3 values were below cutoff, and NCA 50/90 values do not corre
late with CEA in breast cancer. In addition, we found sensitivities of
70, 39, and 42% for lung cancer, colon cancer, and leukemia, respecti
vely. The sensitivity for non-small cell Lung cancer was 85%, however,
compared to 50% for small cell lung cancer. Serum from Leukemia patie
nts showed an overall sensitivity of 43%, but 71% (10 of 14) sera from
patients with chronic myelogenous leukemia were positive compared to,
for example, chronic lymphocytic leukemia where 0 of 7 sera had NCA 5
0/90 values above the cutoff. These studies suggest that NCA 50/90 may
have clinical utility in the management of patients with a variety of
cancers.