title: Breast cancer risk in young women and history of selected medical conditions.
abstract: BACKGROUND
  Several common medical conditions are associated with altered hormone levels, and may thus plausibly influence breast cancer risk. Few studies have examined such relationships, and we utilized a population-based case-control study of young women in the US to examine breast cancer risk following a history of various medical conditions. Relationships between breast cancer and each medical condition examined are biologically plausible, and relevant in terms of public health.
  
  
  METHODS
  The study included 2173 breast cancer cases and 1990 population-based controls from three areas of the US, under 55 years, who were administered a questionnaire including details of physician-diagnosed medical conditions.
  
  
  RESULTS
  No significantly increased or decreased breast cancer risk was associated with a history of thyroid disease, gallbladder disease, colorectal polyps, diabetes, high blood pressure, high cholesterol or surgery for endometriosis. There was some evidence of an increased breast cancer risk associated with ovarian cysts among women who did not receive an oophorectomy (relative risk [RR] = 1.94, 95% CI: 1.0-3.9). Non-significant increases in breast cancer risk were observed following diagnoses of several other cancers, including thyroid cancer, basal cell carcinoma, Hodgkin's disease and malignant melanoma.
  
  
  CONCLUSIONS
  To conclude, our generally null results from this large, population-based study support results from previous studies in providing reassurance that women with a history of several common medical conditions do not appear to be at an increased risk of breast cancer at a young age.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD, USA.
authors.forename: H A
authors.initials: HA
authors.lastname: Weiss
authors.forename: L A
authors.initials: LA
authors.lastname: Brinton
authors.forename: N A
authors.initials: NA
authors.lastname: Potischman
authors.forename: D
authors.initials: D
authors.lastname: Brogan
authors.forename: R J
authors.initials: RJ
authors.lastname: Coates
authors.forename: M D
authors.initials: MD
authors.lastname: Gammon
authors.forename: K E
authors.initials: KE
authors.lastname: Malone
authors.forename: J B
authors.initials: JB
authors.lastname: Schoenberg
mesh_terms: D000328:Adult; D017677:Age Distribution; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D015897:Comorbidity; D016001:Confidence Intervals; D003920:Diabetes Mellitus / Q000453:epidemiology*; D005260:Female; D005833:Genital Neoplasms, Female / Q000453:epidemiology*; D006801:Humans; D006973:Hypertension / Q000453:epidemiology*; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D011159:Population Surveillance; D012016:Reference Values; D018570:Risk Assessment; D012307:Risk Factors; D016019:Survival Analysis; D013959:Thyroid Diseases / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology