We investigated the relationship between the serum level of CA125 befo
re a second-look operation (SLO) and SLO findings in 196 patients with
adenocarcinoma of the ovary. SLO findings were positive in 38 (19.4%)
of 196 patients. The positive rate tended to increase with the clinic
al stage, but SLO findings were positive even in a patient with stage
Ia disease. The pre-SLO serum level of CA125 was positive in 11 patien
ts before SLO, SLO findings were positive in 8 of these 11 patients. T
he highest diagnostic accuracy (37.9%) for the pre-SLO serum level of
CA125 was obtained at a cut-off value of 11 U/ml. Our findings suggest
that a positive pre-SLO serum level of CA125 does not necessarily ind
icate tumor positivity. In addition, we suggest that the cut-off value
for prediction of SLO findings should be below 35 U/ml, which is a co
mmonly used cut-off value.