WASHINGTON, Aug. 14 (Xinhua) -- U.S. researchers said Wednesday they have discovered how a common oral bacterium can trigger a cascade of changes leading to colorectal cancer. The microorganism called fusobacteria, which are found in the mouth, may stimulate bad immune responses and turn on cancer growth genes to generate colorectal tumors, two studies published in the journal Cell Host & Microbe revealed. Colorectal cancer is the second leading cause of cancer-related death in the United States. Recent studies have shown that fusobacteria from the mouth are also abundant in tissues from colorectal cancer patients but it was not known...