BALTIMORE--Some 60% to 80% of ovarian cancer patients recur after
the first round of treatment, and "only about 15% of ovarian
cancer patients who test positive at second-look laparotomy survive
as long as 5 years," Karl F. Hubner, MD, of the University
of Tennessee, Knoxville, said at a nuclear oncology conference
sponsored by the Johns Hopkins Medical Institutions.
Unless the patient undergoes second-look laparotomy, finding a
recurrence is chancy, Neal B. Rosenshein, MD, of Johns Hopkins
School of Medicine, said in his presentation.
A CT scan, Dr. Rosenshein said, is about as good as a "flip
of a coin," and scintigraphy has about the same value. Using
a CA 125 assay is 100% accurate if positive, but no better than
CT if negative. Laparoscopy, besides being painful and expensive,
has a false-negative rate of 35%.
In a search for better noninvasive tools, Dr. Hubner has been
studying positron emission tomography (PET) using F-18 fluorodeoxyglucose
(FDG). Regional and whole body scans have proved useful in locating
metastatic spread, Dr. Hubner said. Studies show that standard
FDG uptake values above 3.2 strongly predict cancer.
"Taken together, negative PET and CT scans are sufficiently
specific that they may obviate second-look surgery," he said.
"This combination has the highest accuracy for both diagnosis
and exclusion of ovarian cancer." He also noted that PET
imaging can be used to optimize the timing of second-look surgery.
Furthermore, PET , a noninvasive procedure, is less expensive:
$2,200 at Dr. Hubner's Knoxville center versus $15,000 for second-look
surgery (for a 5-day hospital stay without complications).
Drawbacks to the process include GI tract activity, which can
be minimized by looking at that activity over time, he said. PET
scan may be obscured by postoperative abscesses or infections
and, in any case, cannot detect lesions under 7 mm in diameter.
Dr. Hubner suggests irrigating the bladder during the scan to
keep bladder activity low.