title: Association of thyroid, breast and renal cell cancer: a population-based study of the prevalence of second malignancies.
abstract: BACKGROUND
  Analysis of the National Cancer Institute's Surveillance, Epidemiology, and End Results data has shown that the incidence of thyroid cancer is higher in patients with a preexisting malignancy and that the incidence of other malignancies is higher in patients with thyroid cancer. The purpose of this study was to evaluate the prevalence of a second malignancy in patients treated for thyroid, breast or renal cell cancer and determine what associations, if any, exist between these cancers.
  
  
  METHODS
  This study utilized the novel data system, Explorys, as its population base. Patient cohorts were constructed using ICD-9 codes, and prevalence rates were obtained for each cancer. Rates of second malignancy were obtained and compared to the baseline prevalence for a particular malignancy.
  
  
  RESULTS
  Female thyroid cancer patients had a 0.67- and twofold increase in prevalence of a subsequent breast and renal cell cancer. Female breast and renal cell cancer patients had a twofold and 1.5-fold increase in the prevalence of thyroid cancer, respectively. Male patients with thyroid cancer had a 29- and 4.5-fold increase in prevalence of subsequent breast and renal cell cancer. Male patients with breast and renal cell cancer had an increased prevalence of subsequent thyroid cancer, 19- and threefold, respectively.
  
  
  CONCLUSIONS
  Our study demonstrated a bidirectional association between thyroid, breast and renal cancer in both male and female patients. This may have important implications for patient follow-up and screening after treatment of a primary cancer.
authors.affiliation: Department of Surgery, Summa Health System, Akron City Hospital, Akron, OH, USA. vanfossv@summahealth.org
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Van Fossen
authors.forename: Scott M
authors.initials: SM
authors.lastname: Wilhelm
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Eaton
authors.forename: Christopher R
authors.initials: CR
authors.lastname: McHenry
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D038801:International Classification of Diseases; D007680:Kidney Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D008297:Male; D016609:Neoplasms, Second Primary / Q000175:diagnosis / Q000453:epidemiology*; D009820:Ohio / Q000453:epidemiology; D015995:Prevalence; D011379:Prognosis; D012042:Registries; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy