Pathologic findings following false-positive screening tests for ovarian cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) cancer screening trial.

Objective: In the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO), ovarian cancer screening with transvaginal ultrasound (TVU) and CA-125 produced a large number of false-positive tests. We examined relationships between histopathologic diagnoses, false-positive test group, and participant and screening test characteristics.

Methods: The PLCO ovarian cancer screening arm included 39,105 women aged 55-74 years assigned to annual CA-125 and TVU. Histopathologic diagnoses from women with false-positive tests and subsequent surgery were reviewed in this analysis: all CA125+ (n=121); all CA125+/TVU+ (n=46); and a random sample of TVU+ (n=373). Demographic and ovarian cancer risk factor data were self-reported. Pathologic diagnoses were abstracted from surgical pathology reports. We compared participant characteristics and pathologic diagnoses by category of false-positive using Pearson χ2, Fisher's exact, or Wilcoxon-Mann-Whitney tests.

Results: Women with a false-positive TVU were younger (P<0.001), heavier (P<0.001), and reported a higher frequency of prior hysterectomy (P<0.001). Serous cystadenoma, the most common benign ovarian diagnosis, was more frequent among women with TVU+ compared to CA-125+ and CA-125+/TVU+ (P<0.001). Benign non-ovarian findings were commonly associated with all false-positives, although more frequently with CA-125+ than TVU+ or CA-125+/TVU+ groups (P=0.019). Non-ovarian cancers were diagnosed most frequently among CA-125+ (P<0.001).

Conclusions: False-positive ovarian cancer screening tests were associated with a range of histopathologic diagnoses, some of which may be related to patient and screening test characteristics. Further research into the predictors of false-positive ovarian cancer screening tests may aid efforts to reduce false-positive results.