title: Association between Metformin Use and Survival in Nonmetastatic Rectal Cancer Treated with a Curative Resection: A Nationwide Population Study.
abstract: OBJECTIVE
  Metformin is associated with an anticancer effect. However, the effects of metformin in rectal cancer are controversial. This study investigated the impact of metformin on the survival of patients with diabetes mellitus and nonmetastatic rectal cancer who underwent curative surgery.
  
  
  METHODS
  The database was provided by the Korea Center Cancer Registry and National Health Insurance Service of the Republic of Korea. A cohort of patients with newly diagnosed rectal cancer between 2005 and 2011 was identified. Drug exposure was defined as receiving the oral hypoglycemic agent for at least 90 days over the period from 6 months before the initial diagnosis of rectal cancer to the last follow-up.
  
  
  RESULTS
  A total of 4,503 patients were prescribed oral hypoglycemic agents and classified as the diabetic group, of which 3,694 patients received metformin for at least 90 days. Unadjusted analyses showed a significantly higher overall survival (hazard ratio, 0.596; 95% confidence interval, 0.506 to 0.702) and rectal cancer-specific survival (hazard ratio, 0.621; 95% confidence interval, 0.507 to 0.760) in the metformin group than in the nonmetformin group. The adjusted overall survival (hazard ratio, 0.631; 95% confidence interval, 0.527 to 0.755) and cancer-specific survival (hazard ratio, 0.598; 95% confidence interval, 0.479 to 0.746) in the group with a medication possession ratio of 80% or greater was significantly higher than in the group with a medication possession ratio of less than 80%.
  
  
  CONCLUSIONS
  Metformin use is associated with overall and cancer-specific survival in diabetic patients with a nonmetastatic rectal cancer treated with a curative resection.
authors.affiliation: Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Young-Jun
authors.initials: YJ
authors.lastname: Ki
authors.affiliation: National Evidence-based Healthcare Collaborating Agency, Seoul, Korea.
authors.forename: Hyo Jeong
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Radiation Oncology, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Mi-Sook
authors.initials: MS
authors.lastname: Kim
authors.affiliation: National Evidence-based Healthcare Collaborating Agency, Seoul, Korea.
authors.forename: Chan Mi
authors.initials: CM
authors.lastname: Park
authors.affiliation: National Evidence-based Healthcare Collaborating Agency, Seoul, Korea.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Ko
authors.affiliation: Department of Radiation Oncology, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Young Seok
authors.initials: YS
authors.lastname: Seo
authors.affiliation: Department of Surgery, Korea Cancer Center Hospital, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Moon
authors.affiliation: National Evidence-based Healthcare Collaborating Agency, Seoul, Korea.
authors.forename: Jin A
authors.initials: JA
authors.lastname: Choi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000188:drug therapy* / Q000453:epidemiology; D013505:Digestive System Surgical Procedures / Q000379:methods; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000627:therapeutic use*; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D009367:Neoplasm Staging; D011159:Population Surveillance; D012004:Rectal Neoplasms / Q000150:complications / Q000453:epidemiology / Q000401:mortality* / Q000628:therapy*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents; D007004:Hypoglycemic Agents; D008687:Metformin
keywords: Colorectal surgery; Diabetes mellitus; Metformin; Rectal neoplasms; Survival