M. Yoshimura et al., ASSESSMENT OF URINARY BETA-CORE FRAGMENT OF HUMAN CHORIONIC-GONADOTROPIN AS A NEW TUMOR-MARKER OF LUNG-CANCER, Cancer, 73(11), 1994, pp. 2745-2752
Background. Some patients with lung cancer have been found to have ele
vated levels of serum immunoreactive human chorionic gonadotropin (hCG
)/hCG beta (IR-beta), but it is uncertain whether it would be valuable
as a tumor marker. Recently, IR-beta has been demonstrated to consist
of at least three different molecules, intact hCG, free hCG beta, and
hCG beta-core fragment (beta-CF), in body fluids. In this study, the
authors qualitatively analyzed IR-beta in the serum and urine of patie
nts with lung cancer and assessed its clinical usefulness as a tumor m
arker. Methods. Highly sensitive and specific enzyme immunoassays were
established to measure intact hCG, free hCG beta, and beta-CF in the
serum and urine of patients with lung cancer. Results. Of 99 patients
with lung cancer, almost half of the patients achieved positive values
of IR-beta in the urine, although only 12 had elevated values of IR-b
eta in the serum. The greater part of the elevated urinary IR-beta was
identified to be beta-CF by gel chromatography on Sephadex G-100 (Pha
rmacia LKB Biotechnology, Tokyo, Japan), leading the authors to assess
its usefulness as a tumor marker for lung cancer. Based on the cutoff
value (0.2 ng/ mg of creatinine) from healthy subjects, the overall p
ositive rate of urinary beta-CF for lung cancer was 48.5% (48 of 99 pa
tients). The incidence of the marker increased with stage of disease,
from 35.7% (15 of 42) in Stage I and 35.7% (5 of 14) in Stage II to 62
.5% (20 of 32) in Stage III and 72.7% (8 of 11) in Stage IV, These pos
itive rates exceeded or equaled those of the serum tumor markers, carc
inoernbryonic antigen, and squamous cell carcinoma (SCC)-related antig
en, measured simultaneously in the same patients. The author were enco
uraged that there was no significant difference in the positive rates
of urinary beta-CF between two major types of lung cancer: adenocarcin
oma (49.2%) and SCC (45.2%). Immunohistochemical study revealed positi
ve staining of IR-beta in the cancer tissues from 5 of 12 patients wit
h elevated levels of IR-beta, in which most of the positive cases had
the elevated levels of serum free hCG beta (>0.5 ng/ml) and/or urinary
beta-CF (>1.0 ng/mg of creatinine). Conclusions. Ectopic production o
f IR-beta by lung cancer is not rare, and urinary beta-CF might be a p
otential tumor marker of lung cancer.