title: Incidental diffuse thyroid 18F-FDG uptake related to autoimmune thyroiditis may be a favorable prognostic factor in advanced breast cancer.
abstract: Patients with breast cancer have a relatively high prevalence of diffuse thyroid uptake of (18)F-FDG related to thyroid autoimmunity. It is postulated that the presence of thyroid autoimmunity has prognostic implications for breast cancer. The aim of this study was to evaluate the prognostic value of incidental diffuse thyroid uptake in breast cancer patients.
  
  
  METHODS
  This was a retrospective observational cohort study in a tertiary referral hospital. We evaluated a total of 564 patients who had undergone surgery for primary breast cancer between January 2006 and December 2009. Patients were divided into 2 groups according to their diffuse thyroid uptake. The main outcome measure was disease-free survival.
  
  
  RESULTS
  Of the 564 patients, 108 (19.1%) showed diffuse thyroid uptake. The median follow-up period was 36.0 mo (range, 1.0-77.0 mo). Both thyroperoxidase and thyroglobulin antibody titers were higher in patients with thyroid uptake than in those without (P < 0.001 for both). Of the 108 patients with thyroid uptake, 5 had a recurrence of breast cancer during the follow-up, whereas 85 without uptake had a recurrence (log-rank statics, 12.28; P < 0.001). The association between diffuse thyroid uptake and tumor recurrence was not significant in multivariate analysis of patients with early-stage breast cancer (hazard ratio, 0.26; 95% confidence interval, 0.06-1.10; P = 0.067). However, the association between diffuse thyroid uptake and breast cancer recurrence was statistically significant in multivariate analysis with adjustment for several prognostic variables (hazard ratio, 0.19; 95% confidence interval, 0.57-0.62; P = 0.006).
  
  
  CONCLUSIONS
  Incidental diffuse thyroid uptake related to autoimmune thyroiditis was an independently favorable prognostic factor in advanced breast cancer. These findings support evidence that thyroid autoimmunity has a beneficial effect on the outcomes of breast cancer patients.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Internal Medicine, Pusan National University Hospital, Busan, Korea.
authors.forename: Sang Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: In Joo
authors.initials: IJ
authors.lastname: Kim
authors.forename: Seong-Jang
authors.initials: SJ
authors.lastname: Kim
authors.forename: Jee Yeon
authors.initials: JY
authors.lastname: Lee
authors.forename: Young Tae
authors.initials: YT
authors.lastname: Bae
authors.forename: Yun Kyung
authors.initials: YK
authors.lastname: Jeon
authors.forename: Bo Hyun
authors.initials: BH
authors.lastname: Kim
authors.forename: Yong Ki
authors.initials: YK
authors.lastname: Kim
mesh_terms: D000368:Aged; D001692:Biological Transport; D001943:Breast Neoplasms / Q000150:complications / Q000175:diagnosis* / Q000378:metabolism*; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008875:Middle Aged; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000378:metabolism*; D013967:Thyroiditis, Autoimmune / Q000150:complications*
chemical_list: D019788:Fluorodeoxyglucose F18