Ca 125 ovarian cancer

SAN DIEGO -- A prospective, multicenter screening trial is investigating whether a longitudinal pattern of CA 125 measurements, rather than a single measurement, offers better sensitivity for detecting ovarian cancer in women at high risk for the disease.

"The interpretation of a woman's CA 125 level involves looking for an elbow pattern rise, over time, rather than evaluating a single absolute level," reported Dr. Steven Skates of Massachusetts General Hospital, Boston.

For further refinement of the measurement's sensitivity, variables such as menopausal status, race, bilateral salpingo-oophorectomy, and smoking also should be considered, because they can alter by at least 10% the critical cut point that indicates further investigation, he said at the annual meeting of the Society of Gynecologic Oncologists.

A total of 2,005 women from 23 U.S. academic medical centers have been enrolled in the trial to date. Of the five ovarian cancers that have been detected, four had levels commensurate with an elbow pattern of rising CA 125 levels. In general, approximately 15%-20% of ovarian cancers do not produce CA 125, Dr. Skates said.

Investigators in the study are using CA 125 levels, measured every 3 months as the first line of screening, followed by transvaginal ultrasonography (TVS) when indicated. Although they are mainly looking for an elbow pattern rise, they also have set cutoff levels to guide them in interpreting initial measurements before a pattern is evident. The cut point is chosen so that 10% of screened women are referred to CA 125 indicated ultrasound annually.

For postmenopausal women, that cut point is 34 U/mL, which is essentially the standard CA 125 cutoff of 35 U/mL.

Similarly, in premenopausal women, although the cut point was initially set at 40 U/mL, the preliminary results from the trial indicate the equivalent cut point is 53 U/mL. African American premenopausal women have a lower equivalent cut point of 39 U/mL, and for premenopausal smokers it's 44 U/mL.

Of the five cancers detected so far, one cancer was particularly worrisome, because the woman exhibited the typical elbow pattern rise in CA 125 levels but repeatedly had normal TVS findings, Dr. Skates said.

"One of the discussion points for the trial's surgical committee based on this case, which has just arisen, is going to be whether the guidelines on exploratory laparoscopy in such situations should be revised and more strongly encouraged, and whether we can calculate a risk beyond which, even with a negative ultrasound, we would encourage exploratory laparoscopy," he said in an interview.

BY KATE JOHNSON

Contributing Writer