title: Metformin Is Associated with a Favorable Outcome in Diabetic Patients with Cervical Lymph Node Metastasis of Differentiated Thyroid Cancer.
abstract: OBJECTIVE
  Type 2 diabetes is known to increase the risk and progression of certain types of cancer. Metformin treatment of diabetic patients is reported to have beneficial effects on some cancers. We evaluated the clinical outcome of diabetic patients with differentiated thyroid cancer (DTC) according to metformin treatment.
  
  
  METHODS
  We reviewed 943 patients diagnosed with DTC after total thyroidectomy between 1995 and 2005 in a tertiary hospital. The study involved 60 diabetic patients and 210 control patients matched for age, sex, body mass index (BMI), and tumor size.
  
  
  RESULTS
  There were no differences in the clinicopathological features and disease-free survival (DFS) between diabetic patients and the control group over 8.9 years of follow-up. Of the diabetic patients with DTC, 35 patients (58%) were treated with metformin. There were no differences in age, sex, BMI, tumor size, antidiabetic medication, glycated hemoglobin, or C-peptide levels in metformin and nonmetformin groups. However, cervical lymph node (LN) metastasis was more prevalent in the metformin group than in the nonmetformin group (OR 3.52, p = 0.035). Among diabetic patients with cervical LN metastasis of DTC, the metformin subgroup (17.1 years) was associated with longer DFS than the nonmetformin subgroup (8.6 years) (HR 0.16, p = 0.021); metformin treatment was also associated with longer DFS in this subgroup in multivariate analysis after adjusting age, BMI, duration of diabetes, presence of tumor at resection margin, and serum thyroglobulin level at ablation (HR 0.03, p = 0.035).
  
  
  CONCLUSIONS
  Metformin treatment is associated with low recurrence in diabetic patients with cervical LN metastasis of DTC.
authors.affiliation: Department of Endocrinology, Dongnam Institute of Radiological and Medical Sciences Cancer Center, Busan, Korea ; Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Eun Kyung
authors.initials: EK
authors.lastname: Jang
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Won Gu
authors.initials: WG
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Hyemi
authors.initials: H
authors.lastname: Kwon
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Yun Mi
authors.initials: YM
authors.lastname: Choi
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Min Ji
authors.initials: MJ
authors.lastname: Jeon
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Tae Yong
authors.initials: TY
authors.lastname: Kim
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Won Bae
authors.initials: WB
authors.lastname: Kim
authors.affiliation: Department of Endocrinology, Dongnam Institute of Radiological and Medical Sciences Cancer Center, Busan, Korea.
authors.forename: Eui Young
authors.initials: EY
authors.lastname: Kim
keywords: Diabetes mellitus; Metformin; Neoplasm metastasis; Recurrence; Thyroid cancer