Is This Bacteria the Cause for the Increase in Colorectal Cancer Cases in Younger Patients?

A study found that the oral bacterium Fusobacterium nucleatum (F. nuc) presents in a greater number of colorectal cancer (CRC) tumors among younger patients (diagnosed before age 45 years) compared with older patients. This finding comes as there has been an increase in the number of CRC cases among younger individuals and may point to a difference in the microbiome as a possible reason for this uptick in cancer. The research was presented at the Gastrointestinal Cancers Symposium.

Researchers compared the intratumoral microbiome in patients with CRC (primary and metastatic tumors) diagnosed before age 45 years versus diagnosed after age 65 years. Researchers extracted DNA from tumors and analyzed them using 165 ribosomal gene sequencing and compared the frequency of Fnuc and other bacterial and fungal DNA in tumors based on patient age.

A total of 18 younger (median age, 39.2 years) and 13 older (median age, 72.8 years) patients were included in the study. A total of 478 unique bacterial and fungal species were detected.

Microbiome in younger versus older patients

F. nuc was observed five younger patients (28%) and three older patients (23%). Researchers observed a significant difference in the rate of Moraxella osloensis in younger versus older patients (11% vs. 46%; P=0.043), representing a fourfold increased rate in younger patients. There was no significant difference in microbiome diversity in younger versus older patients.

“Intratumoral bacterial profiling may discover patterns that explain the rising incidence of CRC in younger individuals and might eventually inform the development of novel therapeutics and adaptive cancer screening methods,” the researchers concluded.

The study is limited by its small patient population.