[Balancing benefits and harms of population-based interventions, using the example of cancer screening]

Clinical effectiveness of cancer screening biomarker tests offered as self-pay health service: a systematic review

BACKGROUND

Biomarker tests are increasingly being offered by laboratories and clinicians as self-pay health services to screen asymptomatic individuals; however, sufficient evidence may not be available to support this practice. We investigated the benefit-harm tradeoffs associated with 11 biomarkers currently offered in Germany as self-pay tests to screen for cancer.

METHODS

We systematically searched bibliographic databases for health technology assessments, systematic reviews and randomized-controlled trials (RCTs) through September 2015. We included publications that analysed cancer screening biomarkers and reported patient-relevant outcomes (mortality, morbidity, quality of life), and potential harms of screening, among asymptomatic individuals in screening and non-screening arms. Language was restricted to English and German. Two reviewers independently screened references; data were extracted and quality of included studies was evaluated by a reviewer and validated by a second reviewer.

RESULTS

Six publications of secondary literature and four publications reporting results from two RCTs were included. For 10 cancer screening biomarkers, no direct evidence on patient-relevant outcomes was available. Only one trial, which simultaneously assessed cancer antigen 125 (CA125) and vaginal ultrasound for ovarian cancer screening, provided the outcome of interest. Screening compared with usual care did not reduce ovarian cancer mortality. Patient harms included overdiagnosis and false-positive results.

CONCLUSION

Although ovarian cancer screening with CA125 showed no benefit, false-positive tests, overdiagnosis and overtreatment were reported. Physicians and laboratories should provide patients with comprehensive information about the lack of evidence and potential harms caused by biomarker screening tests offered as a self-pay health service.