Cancer Screening Companies Are Rapidly Proliferating: Are They Ready for Business?

Cancer screening has been a major research front for decades. The classical circulating biomarkers for cancer (such as PSA, CEA, CA125, AFP, etc.) are neither sensitive nor specific and are not recommended for population screening. Recently, circulating tumor DNA (ctDNA) emerged as a new pan-cancer tumor marker, with much promise for clinical applicability. ctDNA released by tumor cells can be used as a proxy of the tumor burden and molecular composition. It has been hypothesized that if ctDNA is extracted from plasma and analyzed for genetic changes, it may form the basis for a non-invasive cancer detec-tion test. Lately, there has been a proliferation of for-profit companies that will soon offer cancer screening services. Here, we comment on Grail, Thrive, Guardant, Delfi, and Freenome. Previously, we identified some fundamental difficulties associat-ed with this new technology. In addition, clinical trials are exclusively case-control studies. The sensitivities/specificities/ predictive values of the new screening tests have not been well-defined or, the literature-reported values are rather poor. Despite these deficiencies some of the aforementioned companies are already testing patients. We predict that the premature use of ctDNA as a cancer screening tool may add another disappoint-ment in the long history of this field.

Automated summary

Cancer screening has been an important field of research. Traditional biomarkers are not suitable for population screening. Circulating tumor DNA has emerged as a promising new marker for cancer, but there are still challenges and the accuracy of new screening tests needs further definition.