SEATTLE--In patients with advanced epithelial ovarian cancer,
CA 125 concentrations after two cycles of chemotherapy are a powerful
independent predictor of survival, a Southwest Oncology Group
Study (SWOG) has shown.
SWOG statistician Ping-Yu Liu, PhD, and his colleagues obtained
baseline and follow-up CA 125 levels for 101 patients enrolled
in a phase III SWOG study. All patients had suboptimal stage III
or IV ovarian cancer and were receiving chemotherapy--either cisplatin
(Platinol) or carboplatin (Paraplatin) plus cyclophosphamide--every
28 days for six cycles.
"We found that patients with lower CA 125 values at 8 weeks
had a significantly higher chance of longer term survival,"
said Dr. Liu of the SWOG Statistical Center and Fred Hutchinson
Cancer Research Center.
Of the 101 patients, 51 had a CA 125 level less than 35 U/mL (the
cutoff for normal) 8 weeks into the study, ie, 4 weeks after the
second course of chemotherapy. Median survival for these patients
whose CA 125 levels had normalized by 8 weeks was 26 months, compared
with 15 months for the other 50 patients whose CA 125 values remained
above 35 U/mL.
Similarly, for patients whose CA 125 values declined by 50% or
more from their pretreatment level, median survival was 21 months
versus 10 months for those whose values increased or dropped by
less than 50%.
"So overall, patients whose CA 125 values either normalized
or were reduced by 50% or more had an 11 month increase in their
median survival," Dr. Liu said.
Further analysis showed that other prognostic factors, such as
age, performance status, and disease stage, could not explain
the survival difference between those patients with lower and
higher CA 125 values. "In fact, at 8 weeks, CA 125 turned
out to be the single most significant prognostic factor for survival,"