RISK OF DIAGNOSIS OF OVARIAN-CANCER AFTER RAISED SERUM CA-125 CONCENTRATION - A PROSPECTIVE COHORT STUDY

Objective-To determine the risk of invasive epithelial ovarian cancer and fallopian tube cancer associated with a raised concentration of th e tumour marker CA 125 in asymptomatic postmenopausal women. Design-Se rum CA 125 concentration was measured annually in study participants f or one to four years. Participants with a concentration greater than o r equal to 30 U/ml were recalled for abdominal ultrasonography. Follow up was by annual postal questionnaire. Setting-General practice, occu pational health departments, ovarian cancer screening unit in a teachi ng hospital. Subjects-22 000 volunteers, all postmenopausal women grea ter than or equal to 45 years of age; recruited between 1 June 1986 an d 1 May 1990. Intervention-Surgical investigation if the ultrasound ex amination was abnormal. Main outcome measures-Cumulative and relative (invasive fallopian tube) after a specified CA 125 result. Results-49 index cancers developed in the study population during a mean follow u p of 6.76 years. The overall cumulative risk of developing an index ca ncer was 0.0022 for the entire study population and was lower for wome n with a serum CA 125 concentration <30 U/ml (cumulative risk 0.0012) but was appreciably increased for women with a concentration greater t han or equal to 30 U/ml (0.030) and >100 U/ml (0.149). Compared with t he entire study population the relative risk of developing an index ca ncer within one year and five years was increased 35.9-fold (95% confi dence interval 18.3 to 70.4) and 14.3-fold (8.5 to 24.3) respectively after a serum CA 125 concentration greater than or equal to 30 U/ml an d 204.8-fold (79.0 to 530.7) and 74.5-fold (31.1 to 178.3) respectivel y after a concentration greater than or equal to 100 U/ml. Conclusion- CA 125 is a powerful index of risk of ovarian and fallopian tube cance r in asymptomatic postmenopausal women.