title: Pathological features and clinical outcomes of breast cancer according to levels of oestrogen receptor expression.
abstract: OBJECTIVE
  Historically, nuclear staining of ≥10% of invasive tumour cells has been used for oestrogen receptor (ER) positivity. In 2010, ASCO/CAP guidelines recommended the cut-off value be changed to nuclear staining of ≥1%. This study will analyse the relationships between levels of ER expression and clinicopathological features and clinical outcomes, with an emphasis on the ER 1-10% subgroup.
  
  
  RESULTS
  We analysed clinicopathological features in five subgroups based on ER expression levels in 1700 consecutive invasive breast cancer patients diagnosed and treated at our institution between 2000 and 2011. Of the cases, 24% had ER expression <1%, 2% were ER 1-10%, 5% were 11-50%, 5% were 51-70% and 64% were 71-100%. We observed four subgroups of patient cohorts (ER <1%, 1-10%, 11-70% and 71-100%) that were unique in Nottingham grade, nuclear grade, progesterone receptor expression and disease-free survival. Of the 341 patients with follow-up data, we found no significant differences in pathological features between patients in the ER 11-50% and ER 51-70% subgroups.
  
  
  CONCLUSIONS
  These data support the important role of ER in breast cancer, and the importance of accurate testing and quantitative reporting for ER. Tumours with ER 1-10% are not common, and further studies are needed to understand more clearly this subgroup of breast cancer.
authors.affiliation: Department of Pathology, University of Rochester Medical Center, Rochester, NY, USA; Department of Pathology, West China Hospital, Sichuan University, Sichuan, China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jianmin
authors.initials: J
authors.lastname: Wang
authors.forename: Kristin A
authors.initials: KA
authors.lastname: Skinner
authors.forename: Michelle
authors.initials: M
authors.lastname: Shayne
authors.forename: Steven I
authors.initials: SI
authors.lastname: Hajdu
authors.forename: Hong
authors.initials: H
authors.lastname: Bu
authors.forename: David G
authors.initials: DG
authors.lastname: Hicks
authors.forename: Ping
authors.initials: P
authors.lastname: Tang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D018270:Carcinoma, Ductal, Breast / Q000145:classification / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008875:Middle Aged; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism; D013629:Tamoxifen / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D018931:Antineoplastic Agents, Hormonal; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D013629:Tamoxifen
keywords: breast cancer; expression levels; oestrogen receptor; pathological features