p21(WAF1) expression and endocrine response in breast cancer

J Pathol. 1999 Jun;188(2):126-32. doi: 10.1002/(SICI)1096-9896(199906)188:2<126::AID-PATH340>3.0.CO;2-O.


An immunocytochemical assay for the p53-regulated protein product of the WAF1/Cip1 gene, p21(WAF1) (p21), was developed and applied to archival primary breast tumour material from 91 patients whose subsequent recurrent disease was treated with assessable courses of endocrine therapy. Nuclear localization of p21 protein was observed in 76 (82.4 per cent) cases. Status cut-offs were established and 29 (31.9 per cent) were deemed negative, 39 (42.9 per cent) weakly positive, and 23 (25.3 per cent) strongly positive. p21 status was inversely correlated with p53 protein (p=0.047) but did not relate to oestrogen receptor (ER) status, response to endocrine therapy, or time to further disease progression (TTP). Highly p21-positive patients had a significantly improved overall survival time (p=0. 020). Co-assessment of p21 and p53 subgroups revealed p21+/p53- patients to have good survival characteristics, whilst p21-/p53+ patients did poorly (p=0.008). The p21-/p53- patients overall did intermediately well, but Ki67-defined cellular proliferation analysis of these revealed two subclasses: those with high proliferation and poor survival times resembling the p21-/p53+ phenotype, and those with less proliferative tumours with good survival, similar to the p21+/p53- group. The significance of these results is discussed in the light of recent research concerning the role of p21 and p53 in breast cancer aetiology.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / analysis*
  • Breast Neoplasms / chemistry*
  • Cell Nucleus / chemistry
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins / analysis*
  • Female
  • Humans
  • Immunohistochemistry
  • Ki-67 Antigen / analysis
  • Middle Aged
  • Receptors, Estrogen / analysis
  • Survival Analysis
  • Tumor Suppressor Protein p53 / analysis


  • Biomarkers, Tumor
  • CDKN1A protein, human
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Ki-67 Antigen
  • Receptors, Estrogen
  • Tumor Suppressor Protein p53