OVX1 radioimmunoassay complements CA-125 for predicting the presence of residual ovarian carcinoma at second-look surgical surveillance procedures.
OBJECTIVE
At second-look surgical surveillance procedures, normal CA-125 levels can be associated with persistent disease in 50% to 60% of patients. A novel radioimmunoassay (RIA) has been evaluated for the ability to identify patients with persistent disease who have normal levels of CA-125.


METHODS
The OVX1 double-determinant assay used a murine monoclonal antibody to detect an epitope on a high-molecular weight mucin-like glycoprotein.


RESULTS
Apparently healthy individuals had serum OVX1 levels of 2.23 +/- 2.48 U/mL (mean +/- SD). Elevated serum OVX1 levels (> 7.2 U/mL) were found in 5% of 184 normal individuals and in 70% of 93 epithelial ovarian cancer patients with clinically evident disease. Among sera from these ovarian cancer patients, OVX1 was elevated in 68% of 76 samples with CA-125 levels more than 35 U/mL and in 76% of 17 samples with CA-125 levels less than 35 U/mL. In serum samples obtained at the time of positive second-look laparotomy, 59% of 41 patients with CA-125 levels less than 35 U/mL had elevated OVX1 antigen levels, whereas 41% of 22 patients with CA-125 levels more than 35 U/mL had elevated serum OVX1 levels. In patients with negative second-look laparotomies, false-positive results were eliminated by increasing the threshold of OVX1 to 10.5 U/mL. At this level, 32% of 41 patients with positive second-look operations had an elevated OVX1 level, despite a normal CA-125 level. When used in combination, CA-125 (> 35 U/mL) and OVX1 (> 10.5 U/mL) detected persistent disease in 56% of 63 patients with positive surveillance procedures, compared with 35% when CA-125 was used alone (P < .05).


CONCLUSIONS
An elevated OVX1 level can alert oncologists to the possibility that ovarian cancer has persisted, despite the return of CA-125 to a normal range.
Xu
F J
FJ
Duke University Medical Center, Durham, NC 27710.
Yu
Y H
YH
Daly
L
L
DeSombre
K
K
Anselmino
L
L
Hass
G M
GM
Berchuck
A
A
Soper
J T
JT
Clarke-Pearson
D L
DL
Boyer
C
C
D000818:Animals; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm / Q000097:blood*; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D005260:Female; D006023:Glycoproteins; D006801:Humans; D051379:Mice; D009369:Neoplasms / Q000276:immunology; D010049:Ovarian Diseases / Q000276:immunology; D010051:Ovarian Neoplasms / Q000276:immunology* / Q000601:surgery*; D011237:Predictive Value of Tests; D011506:Proteins; D011863:Radioimmunoassay; D012016:Reference Values; D012044:Regression Analysis; D012086:Reoperation
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D015295:Antigens, Tumor-Associated, Carbohydrate; D014408:Biomarkers, Tumor; D006023:Glycoproteins; C086414:OVX1 antigen; D011506:Proteins