Story perspectives

Experts Warn: DNA Cancer Tests Yield High False Positives

4/8/2026

Summary

Story summary

Dr. Roach, a physician, notes that cell-free DNA testing for cancer screening detects only 10%–30% of cancers, despite claims of high specificity.
For stomach cancer, only 3% of positive results are true positives, increasing false positives.
An 85-year-old patient with polycythemia vera faces anxiety from false positives and potential misdiagnoses.
Dr. Roach advises caution, saying screening should be reserved for healthy individuals whose life expectancy justifies surgical risks.

1 of 1

Story summary

Dr. Roach, a physician, notes that cell-free DNA testing for cancer screening detects only 10%–30% of cancers, despite claims of high specificity.
For stomach cancer, only 3% of positive results are true positives, increasing false positives.
An 85-year-old patient with polycythemia vera faces anxiety from false positives and potential misdiagnoses.
Dr. Roach advises caution, saying screening should be reserved for healthy individuals whose life expectancy justifies surgical risks.