A Randomized Study of Screening for Ovarian Cancer: A Multicenter Study in Japan

Abstract

Interest in screening for ovarian cancer, which is common in developed countries, has grown in recent years. This study, which seems to be the first prospective randomized report of ovarian cancer screening, was designed to establish a better strategy for detecting early cancers. Asymptomatic postmenopausal women, seen in the years 1985 to 1999, were randomly assigned to an intervention group (n = 41,688) or to a control group (n = 40,799) and were followed up for an average of 9.2 years. The original goal was to offer annual screens comprising pelvic ultrasonography and a serum cancer antigen 125 (CA-125) test to women in the intervention group. Those with abnormal ultrasound findings or elevated CA-125 were referred to a gynecologic oncologist for surgical assessment. In late 2002 when the code was broken, 27 cancers were found in screened women and 8 more were diagnosed outside the screening program. Rates of detecting ovarian cancer were 0.31 per 1000 at the prevalent screen and ranged from 0.38 to 0.74 per 1000 at subsequent screens. Rates increased on successive screens. Ovarian cancer developed in 32 control women. Fewer women in the screened group than in the control group had advanced-stage disease. The proportion of stage I ovarian cancer was higher in screened than in control women (63% vs. 38%), but the difference fell short of statistical significance. The histologic type of index cancers was similar in the screened and control groups, as were tumor grade and the use of adjuvant chemotherapy. More women in the screening group than in the control group had no disease or only microscopic disease, but this difference also was not statistically significant. Continuing follow-up of this cohort is expected to provide further information about the effects of screening for ovarian cancer on asymptomatic postmenopausal women.