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Ovarian cancer is highly lethal because symptoms are slow to emerge and late-stage diagnosis therefore is common; accordingly, clinicians often are asked about screening. From late 1993 through mid-2001, U.S. investigators for the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial randomized 78,216 women (age range, 55–74) to annual screening with serum cancer antigen (CA) 125 testing plus vaginal ultrasound or to usual care. Positive screens were defined by CA 125 levels ≥35 U/mL or abnormal ultrasound findings. In 2009, PLCO results showed that screening had low positive predictive value (JW Womens Health Apr 16 2009). Now, PLCO investigators report effects of screening on ovarian cancer mortality.
The proportion of screen-detected cancers that were late-stage was only slightly lower than the proportion of cancers detected at late stages during usual care (69% and 78%, respectively). Ovarian cancer deaths occurred in 118 and 100 women in the screening and usual-care groups, respectively (ovarian cancer death rates, 3.1 and 2.6 per 10,000 person-years). Of 3285 women with false-positive screening results, 1080 underwent surgical follow-up; 163 of these women (15%) experienced one or more serious complications.
Buys SS et al. Effect of screening on ovarian cancer mortality: The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Randomized Controlled Trial. JAMA 2011 Jun 8; 305:2295.
Comment
The authors note that their discouraging findings might reflect the rapid progression of aggressive ovarian tumors, making detection with annual screening ineffective. Moreover, some screen-detected tumors might never have been destined to cause clinical problems. Finally, the serious perioperative complications associated with follow-up of false-positive screening results are sobering. Although effective screening approaches might emerge someday, the findings of the PLCO trial should strengthen our current resolve to “just say no” to ovarian cancer screening.