The effect of metformin use on hypopharyngeal squamous cell carcinoma in diabetes mellitus patients

Background
Metformin is proven to improve the prognosis of various cancers, but it is unknown if metformin could ameliorate hypopharyngeal cancer in diabetes mellitus patients. This was a retrospective cohort study, and the effect and survival outcome of metformin on hypopharyngeal cancer with diabetes mellitus was investigated.
Methods
There were 141 hypopharyngeal cancer patients collected in a tertiary referral center from December 1st, 2011 to December 31st, 2013. There were 49 patients without diabetes mellitus (DM) and 92 patients with DM. In the 92 DM patients, there were 43 patients with metformin used and 49 patients without metformin used. All received patients followed up until September 1st, 2015.
Results
There was no significant difference in patients’ characteristics between the non-DM and DM groups, and also no significant difference in clinical T stage, N stage, metastatic condition, and disease stage between the non-DM and DM groups. DM with metformin patients had lower metastasis rates and better overall survival (OS) (p = 0.011) and disease-free survival (DFS) (p = 0.004) compared to non-DM and DM without metformin. Multivariate analysis also showed a better OS and DFS in DM-Met (+) with advanced hypopharyngeal cancer but not in early stage.
Conclusion
There was less distant metastasis and better survival outcomes in hypopharyngeal cancer DM patients who use metformin.