title: [Clinical characteristics of bilateral primary breast cancer: a report of 100 cases].
abstract: OBJECTIVE
  Women with breast cancer have an increased risk of new primary tumors of the contralateral breast. This study was to analyze the clinical characteristics of bilateral primary breast cancer (BPBC), and explore risk factors of BPBC.
  
  
  METHODS
  Clinical data of 100 patients with BPBC and 200 patients with unilateral primary breast cancer (UPBC) were compared.
  
  
  RESULTS
  The age of disease and age of menarche of BPBC patients were significantly younger than those of UPBC patients (P<0.05). Compared with UPBC patients, BPBC patients had a significantly greater prevalence of family history (15% vs. 5%, P<0.01); incidence rate of breast cancer before menopause was significantly higher in BPBC patients than in UPBC patients (70% vs. 58%, P<0.05). Pathologically positive rate of ipsilateral axillary lymph nodes was not significantly different between the 2 groups. The radiation treatment proportion in metachronous BPBC patients was not significantly different from that in UPBC patients (69% vs. 58%, P>0.05).
  
  
  CONCLUSIONS
  Compare with UPBC patients, BPBC patients have a significantly greater prevalence of family history, and are younger. The estrogen might be closely related to BPBC, but the lymphatic metastasis ability of the first tumor in BPBC is similar to that of UPBC.
authors.affiliation: Department of Breast, Cancer Hospital, Tianjin Medical University, Tianjin, P.R. China.
authors.forename: Meng
authors.initials: M
authors.lastname: Wang
authors.forename: Zhi-Yi
authors.initials: ZY
authors.lastname: Fang
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001365:Axilla; D001943:Breast Neoplasms / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis; D008572:Menarche; D008593:Menopause; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000473:pathology; D016609:Neoplasms, Second Primary / Q000235:genetics / Q000473:pathology; D012307:Risk Factors