Can metformin improve 'the tomorrow' of patients treated for oesophageal cancer?

Introduction: Recent studies suggest that the use of metformin is associated with reduced cancer incidence and improved prognosis in patients with oesophageal cancer. We explored the relationship between the use of metformin and outcome (pathologic response rate, distant metastasis-free and overall survival) in our mono-institutional cohort of patients treated for oesophageal cancer. Material and methods: Between 2008 and 2014, a total of 196 patients with oesophageal cancer (ages ranged from 37 to 82 years) eligible for curative treatment entered the study. Patients were categorized as non-diabetic (n = 172), diabetic not taking metformin (n = 5) or diabetic taking metformin (n = 19). The majority of patients were treated with trimodality therapy (n = 189). Pathologic response was graded according to Mandard's tumour regression score at the time of surgery. Distant metastasis-free and overall survival were calculated using the Kaplan-Meier method with log rank comparisons performed to determine significance. Results: The overall pathologic complete response rate for the study population was 26%. It was 25% for patients not using metformin and 39% for diabetics taking metformin (p = 0.260). The two-year overall survival rate for the whole group was 59%. Use of metformin was associated with a significantly better distant metastasis-free survival rate (p = 0.040) or overall survival rate (p = 0.012). Multivariate analysis using Cox regression found that metformin treatment significantly prolonged survival (p = 0.043). Conclusion: In our population-based study, the use of metforrnin was associated with an improved overall and distant metastasis-free survival rate in patients with oesophageal cancer. These data are complementary to one other clinical study and warrant further prospective study.