Of cancers that strike both men and women, colorectal cancer is the No. 2 killer in the US, reports the CDC, claiming more than 50,000 lives in 2013.

Previous studies out of Harvard found that a common oral bacteria accelerates the cancer's growth in animals, but since the so-called fusobacteria are more prevalent in the mouth than the gut, it remained unclear how fusobacteria localize to the cancer.

In a new study published in Cell Host & Microbe, researchers out of Israel and Harvard get at that mystery, finding bacteria may travel from the mouth to the gut and colon via the bloodstream.

They tested this by injecting fusobacteria into the tail veins of mice with either precancerous or malignant colorectal tumors; the researchers subsequently detected fusobacteria in the tumors, per a press release.

What's more, the researchers found that fusobacteria carry a protein called Fap2 that binds to a sugar called Gal-GalNac found on the surface of colorectal tumors, reports Medical News Today.

While study author Wendy Garrett warns that "it may not be possible to prevent oral microbes from entering the bloodstream and reaching colorectal tumors," it's possible that drugs that target Fap2 or Gal-GalNac might impede the binding and prevent fusobacteria from contributing to tumor development.

And Garrett says the research could bear other fruit: "If we know how fusobacteria localize and become enriched in colon tumors, hopefully we can utilize the same or similar mechanisms to guide and deliver cancer therapeutics to colon tumors." (One in seven colorectal cancer patients is now under this age.)

This article originally appeared on Newser: How Bacteria in Your Mouth Make Colon Cancer Worse

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