A grilled chicken sandwich from a fast-food restaurant can cause cancer, a U.S. group of doctors charged in a lawsuit filed Thursday against seven fast-food chains including McDonald's and Burger King.

The Washington-based Physicians Committee for Responsible Medicine said in their lawsuit that an independent lab had found a dangerous carcinogenic compound called PhIP in grilled chicken samples taken from the restaurants.

"Even a grilled chicken salad increases the risk of breast cancer, prostate cancer, and other forms of this lethal disease," PCRM president Neal Barnard said in a press release.

PhIP is one of a group of carcinogenic compounds found in grilled meat. The compound has been listed on the California governor's list of cancer-causing chemicals for more than a decade.

Chick-fil-A, Chili’s, Applebee’s, Outback Steakhouse, and TGI Friday’s were also named in the lawsuit.