PHILADELPHIA – A common screening test failed to detect potentially cancerous colon growths 95 percent of the time, falsely reassuring patients and doctors, according to a new study.

Researchers found that the digital, in-office test on stool samples was not as reliable as a six-sample test given to patients to do on their own at home – although even that test detected potentially cancerous growths less than 24 percent of the time.

The study, published Tuesday in the Annals of Internal Medicine, was conducted at 13 Veterans Affairs medical centers and involved 2,665 patients – most of them men – who were given the at-home test and the in-office test followed by a colonoscopy.