The number of teeth is a prognostic indicator for chemotherapy in colorectal cancer.

Background: The oral and gut microbiomes are linked to prognosis in colorectal cancer patients undergoing surgery, chemotherapy, or radiotherapy. Dysbiosis in the oral microbiome can lead to tooth decay, periodontitis, and gingivitis, resulting in tooth loss. This study examined the relationship between tooth count and chemotherapy outcomes in colorectal cancer patients.

Method: This retrospective cohort study involved 42 patients receiving chemotherapy for unresectable advanced or metastatic colorectal cancer at Tokushima University Hospital between October 2016 and December 2021. Prior to chemotherapy, dental panoramic radiographs were taken to determine tooth count. Patients were grouped based on the number of teeth (≥17 vs. ≤16), and overall survival (OS), progression-free survival (PFS), and adverse events were compared.

Results: Patients with ≤16 teeth had significantly worse OS than those with ≥17 teeth (p = 0.024). PFS tended to be worse in patients with ≤16 teeth, albeit without significance (p = 0.097). The incidence of various adverse events did not differ between the groups. Anemia was the most common adverse event in patients with ≤16 teeth. Conversely, neutropenia was the most common adverse event in patients with ≥17 teeth.

Conclusion: The number of teeth could be easily examined prognostic factor for chemotherapy in colorectal cancer. J. Med. Invest. 72 : 134-138, February, 2025.