title: Risk for distant recurrence of breast cancer detected by mammography screening or other methods.
abstract: BACKGROUND
  Selection of systemic adjuvant therapies for women diagnosed as having breast cancer is based on risk estimations for cancer recurrence. In such estimations, tumors detected by mammography screening are considered to be associated with a similar risk of recurrence as tumors of similar size found by other methods.
  
  
  OBJECTIVE
  To compare the risk of recurrence and survival among women with cancerous tumors detected by mammography screening compared with other methods (outside of screening).
  
  
  METHODS
  Retrospective study comparing clinical, histopathological, and biological features of cancerous tumors detected by mammography screening compared with tumors detected outside of screening. Women diagnosed as having breast cancer in 1991 or 1992 were identified from the Finnish Cancer Registry (n = 2842). The median follow-up time was 9.5 years. Cancer biological variables were analyzed from tumor tissue microarrays using immunohistochemistry or in situ hybridization and included ERBB2, TP53, and MK167 expression and ERBB2 amplification data.
  
  
  METHODS
  Univariate and multivariate analyses of potential risk factors for distant recurrence of breast cancer and 10-year survival.
  
  
  RESULTS
  Of the 1983 women with unilateral invasive breast cancer, data on tumor diameter were available for 1918 women. Women with cancerous tumors detected by mammography screening had better estimated 10-year distant disease-free survival than women with tumors found outside of screening (tumor size of < or =10 mm [n = 386] 92% vs 85% [P =.04]; 11-20 mm [n = 808] 88% vs 76% [P<.001]; 21-30 mm [n = 409] 86% vs 63% [P =.008]; >30 mm [n = 315] 68% vs 50% [P =.12], respectively). In a Cox multivariate model that included cancer biological factors, the relative hazard ratio for distant recurrence among women with tumors detected outside of screening (HR, 1.90; 95% confidence interval, 1.15-3.11) was significantly higher than among women with tumors detected by mammography screening (P =.01). Breast cancer diagnosis by mammography screening was an independent prognostic variable reducing the relative HR for distant recurrence. This effect was equal to or greater than the effect of 1-cm decrease in tumor diameter (HR, 1.20; 95% confidence interval, 1.10-1.31).
  
  
  CONCLUSIONS
  Cancerous tumors detected by mammography screening are associated with a better prognosis than tumors of similar size found outside of screening. The risk of distant metastases is overestimated for women diagnosed as having cancer by mammography screening unless the method of detection is taken into account in risk estimations.
authors.affiliation: Department of Oncology, Helsinki University Central Hospital, Helsinki, Finland. heikki.joensuu@hus.fi
authors.forename: Heikki
authors.initials: H
authors.lastname: Joensuu
authors.forename: Tiina
authors.initials: T
authors.lastname: Lehtimäki
authors.forename: Kaija
authors.initials: K
authors.lastname: Holli
authors.forename: Liisa
authors.initials: L
authors.lastname: Elomaa
authors.forename: Taina
authors.initials: T
authors.lastname: Turpeenniemi-Hujanen
authors.forename: Vesa
authors.initials: V
authors.lastname: Kataja
authors.forename: Ahti
authors.initials: A
authors.lastname: Anttila
authors.forename: Mikael
authors.initials: M
authors.lastname: Lundin
authors.forename: Jorma
authors.initials: J
authors.lastname: Isola
authors.forename: Johan
authors.initials: J
authors.lastname: Lundin
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000401:mortality* / Q000473:pathology; D005260:Female; D005387:Finland; D006801:Humans; D008327:Mammography; D008403:Mass Screening; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis
chemical_list: D014408:Biomarkers, Tumor