Influence of Metformin Use on Treatment Outcome in NSCLC Patients

There are preliminary clinical and preclinical data suggesting that patients suffering from non-insulin-dependent diabetes mellitus, treated with metformin, have improved local tumor control. The reduction in oxygen consumption of tumor cells and thus a relative reduction in the tumor's hypoxia may be responsible for this.

Non-small cell lung cancer is the most frequent solid tumor in many Western countries and the number one cause of cancer-related death. Even though the introduction of concurrent chemoradiotherapy has improved local tumor control and thus overall survival, 5-year overall survival is still as low as 14%. Furthermore, many patients are not eligible to undergo concurrent treatment thus reducing their chances to defeat this disease. Additionally, concurrent chemoradiotherapy is associated with increased toxicity compared to sequential treatment. Therefore, alternative additives improving the effect of radiotherapy without increasing toxicity to an unbearable level are searched for. One possible pharmaceutical is metformin; many patients have been using it in the past without evident increased toxicity, it is cheap, and widely available.

Thus, the aim of this study is to test the hypothesis that metformin increases overall survival without enhancing treatment-related toxicity. For this means, in three cohorts of patients suffering from advanced stage non-small cell lung cancer and all undergoing concurrent radiochemotherapy: 1. Patients with diabetes mellitus treated with metformin only; 2. Patients with insulin-dependent diabetes mellitus not treated with metformin; 3. The remaining patients serving as controls. Using Kaplan-Meier statistics as well as uni- and multivariate analysis, the overall survival and toxicity of these cohorts will be compared. Other potentially confounding factors will be tested as secondary endpoints.