title: Invasive breast cancer: stratification of histological grade by gene-based assays: a still relevant example from an older data set.
abstract: OBJECTIVE
  A Netherlands Kanker Institute data set provided the results of gene-based assays (GBAs) and histological grades of 295 patients with invasive breast cancer. Grade is the first prognostic assay available after a cancer diagnosis. Given this time-line of actual practise, the aim was to study how gene-based assays further stratify histologic grade.
  
  
  RESULTS
  Emphasis was placed on evaluation of a simple decision tree and on study of the recurrence score (RS). The decision tree determined three risk stratifications. Tumours that were both intermediate grade (IG) and low-RS were grouped with low grade, and tumours that were IG and high-RS were coupled with high grade. IG and intermediate-RS tumours comprised the third category. Survival analysis was performed with respect to the three stratifications. Cramer's V statistic was used for concordance analysis. The mixed grade-RS classifier showed significant survival stratification (P < 0.00001). The mixed classifier was concordant with the 70-gene assay (Cramer's V = 0.57). Recurrence score alone had a 0.59 Cramer's V with the gene assay. Because two-thirds of tumours were of either low or high grade, concordance was maintained despite the majority of classifications having been determined by grade alone.
  
  
  CONCLUSIONS
  There is no compelling reason to test low- and high-grade tumours further by GBAs.
authors.affiliation: Department of Pathology, South Austin Medical Center, Austin, TX, USA.
authors.forename: Leslie
authors.initials: L
authors.lastname: Dalton
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D030541:Databases, Genetic; D003663:Decision Trees; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000378:metabolism; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009426:Netherlands; D011379:Prognosis
chemical_list: D019394:Ki-67 Antigen
keywords: breast cancer; gene; grade recurrence score; molecular prognosis