Neoadjuvant Metformin in Association to Chemoradiotherapy for Locally Advanced Rectal Cancer

Inclusion Criteria

• •18 years or older;
• •biopsy proven poorly differentiated carcinoma or adenocarcinoma of the rectum;
• •lesions located within 12 cm of the anal verge (from colonoscopy assessment);
• •ability to tolerate oral treatment;
• •locally advanced tumor, classified by the presence of positive regional lymph nodes or primary tumor invasion beyond the serosa (T3 or T4), assessed by MRI;
• •eligibility for curative surgery (no distant metastasis or invasion of bony structures of the pelvis);
• •Performance Status (PS) Eastern Cooperative Oncology Group (ECOG) 0-2;
• •adequate hematologic functions (hemoglobin ≥ 10 g / dL \[5.6 mmol / L\]; neutrophil count ≥ 1,500 / mm3 and platelet count ≥ 100,000 / mm3), adequate renal function (serum creatinine less than 1.5 times the UNL) and adequate hepatic function (bilirubin less than 1.5 times the UNL; aspartate aminotransferase and alanine aminotransferase less than 2.5 times the UNL);