Current screening recommendations are that adults over age 50 should take a six-sample fecal occult blood test (FOBT) at home and return the stool samples to their physicians for interpretation.
Positive tests should be followed up with a colonoscopy.
Unfortunately, patients often do not complete the home FOBT tests, so doctors sometimes do a single FOBT test in the office.
In a prospective study of 3,121 people without symptoms for colorectal cancer, researchers found that the single office-based FOBT missed advanced precancerous lesions 95% of the time.
Researchers identified 284 people with colorectal cancer or large polyps likely to become cancer.
Of these, only 5% had positive results on a single office-based FOBT, while 24% had positive results on the six samples taken at home.
|Nearly 30% of physicians reported they did not follow-up a positive FOBT with an immediate colonoscopy|
|Annals of Internal Medicine|
In a national survey of 1,147 primary care physicians and 11,365 people eligible for colorectal cancer screening, 90% of the doctors reported using FOBT at least once per month and one-third of these reported using only a single FOBT rather than the home test.
The researchers found that nearly 30% of physicians reported they did not follow-up a positive FOBT with an immediate colonoscopy.
In addition, the research team noted that about a quarter of the patients reported having FOBT, and one-third of these reported having only a single test in the office.
An editorial writer calls the 2 studies shocking and concludes that primary care physicians must reexamine their colorectal cancer screening practices (Editorial, p. 146).