Bacteria Residing in the Mouth Discovered in CRC Tumors

Cases of colorectal cancer (CRC) are increasing among young people at an alarming rate, prompting the recommended age for screening to be lowered to 45 years. While several risk factors for developing CRC have already been identified, a surprising one has recently been linked to bad breath.

A recent study has shed light on a specific oral organism that may be responsible for CRC. Fusobacterium nucleatum (Fn), a bacterium normally found in the human oral cavity and rarely in the lower gastrointestinal tract of healthy individuals, is found in high concentrations in CRC tumors. High levels of Fn within the tumor have been associated with higher rates of recurrence, metastasis, and poor patient prognosis.

The study examined approximately 200 CRC tumors and collected stool samples from 1,246 individuals in a case-control study. Two distinct subspecies of Fn bacteria were identified: Fna C1 and Fna C2. Of these two, Fna C2 was found to dominate the CRC tumors and provide protection against cancer-fighting drugs. This means that patients with high levels of Fna C2 in the gastrointestinal tract have a worse prognosis and do not respond well to treatment, resulting in an increased risk of recurrence. Fna C2 was present in 50% of the CRC tumors analyzed in the study. Interestingly, Fna C2 is able to withstand high levels of stomach acid, allowing it to travel from the oral cavity through the stomach, while Fna C1 is limited to the oral cavity.

Researchers worldwide are only beginning to scratch the surface of understanding cancer and developing effective treatments. However, this study provides valuable insight into the connection between oral health and CRC, potentially leading to the development of antibiotics specifically designed to target these bacteria at an early stage, thereby preventing CRC or improving treatment outcomes. In the meantime, the best approach is to maintain proper oral hygiene and regularly visit the dentist to prevent CRC.

Emmanuel Olaniyan is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.