Formula points to family risk for a cancer

``It is quite simple -- the authors couldn't have made it any easier," said Dr. David Weinberg, a gastroenterologist at Fox Chase Cancer Center in Philadelphia who had no role in the study.

The findings appear in today's New England Journal of Medicine.

They come from a huge effort to analyze every case of colon cancer in Scotland from 1999 to mid-2003 involving people under 55. Cancers diagnosed earlier in life are more likely to be from inherited mutations.

The most common of these mutations cause the Lynch syndrome, a type of colon cancer that progresses very quickly. These mutations also raise the risk of uterine, ovarian, and other forms of cancer, making it important to identify relatives who may be carriers.

Researchers tried to devise a simple way to screen patients and find which ones should get the expensive tests.

The researchers used the formula plus a relatively simple $300 lab analysis on the 870 participants in the study and successfully identified two-thirds of the patients who had the mutations.