Bacteria Linked to More Aggressive Colon Cancer, Increased Recurrence Risk

The presence of the bacterium Fusobacterium within colon and rectal cancer tumors is associated with more aggressive forms of the disease and an increased risk of recurrence after treatment, according to a Spanish study. This discovery may pave the way for using Fusobacterium as a biomarker to help doctors identify patients most vulnerable to cancer returning and to select the most appropriate therapies.

The study, led by a team from the Vall d'Hebron Institute of Oncology in Barcelona, published its findings in the journal ESMO Open. Researchers analyzed data from 740 patients with surgically removable colon and rectal cancer. Their results indicated that approximately 21% of these patients had tumors containing Fusobacterium. This presence correlated with lower chances of remaining disease-free and a higher likelihood of recurrence compared to patients whose tumors did not harbor the bacterium.

Study authors noted that over 30% of patients with stage II and III colon and rectal cancer experience recurrence despite surgery and chemotherapy. This highlights the need for new biomarkers to better identify patients at higher risk of the tumor returning and to guide treatment decisions more precisely. Dr. Paolo Nuciforo, head of the Molecular Oncology Group at the institute and lead researcher, stated that current methods have limited ability to predict which patients will truly benefit from chemotherapy post-surgery. He believes the study's findings could improve patient risk stratification.

Furthermore, the research revealed that chemotherapy after tumor removal was more effective in patients whose tumors lacked Fusobacterium, whereas patients with the bacterium in their tumor tissue did not show the same benefit. The team also identified another significant indicator: the persistent presence of the bacterium in stool samples after surgery is linked to an increased risk of cancer returning. Fusobacterium was detected in stool samples up to three years before recurrence, suggesting a potential for closer patient monitoring and earlier therapeutic intervention in the future. Researchers suggest that analyzing for Fusobacterium could become part of post-surgical examinations, alongside other clinical and molecular markers, to help design treatment plans tailored to each patient's biological characteristics.