Axillary lymph node status of operable breast cancers by combined steroid receptor and HER-2 status: triple positive tumours are more likely lymph node positive

Aims To examine the frequency of axillary lymph node (ALN) invasion of operable breast cancers by their combined oestrogen receptor (ER), progesterone receptor (PR) and HER-2 status. Methods 2227 recently operated cases in one centre were retrieved from the Multidisciplinary Breast Centre database and stratified according to their combined immunohistochemical (IHC) expression of ER/PR/HER-2 status. An equivocal HER-2 status was further analysed by Fluorescence in situ Hybridisation (FISH). The following 6 groups were considered: ER(-)PR(-)HER-2(-) (NNN; triple negative), ER(-)PR(-)HER-2(+) (NNP), ER(+)PR(-)HER-2(-) (PNN), ER(+)PR(-)HER-2(+) (PNP), ER(+)PR(+)HER-2(-) (PPN), ER(+)PR(+)HER-2(+) (PPP; triple positive). For ALN, the following variables were tested in uni- and multivariate models: age at diagnosis (years), tumour size (mm), tumour grade, ER, PR, HER-2 and the combined steroid receptor and HER-2 status. Likelihood ratio chi(2)-tests were used for univariate analysis and logistic regression for multivariate analysis. Results Triple positive tumours had a higher likelihood of being ALN positive than others (56.2% versus 35.7%; P <0.0001). Univariate logistic regression also withheld age, size, grade and HER-2 as predictors of ALN involvement. Final multivariate logistic regression revealed age, size, grade and PPP versus non-PPP to be independent predictors of ALN involvement; the odds ratio (OR) and 95% CI for PPP versus non-PPP tumours was 2.169 (1.490-3.156). Conclusion Our data provide insight into the natural history of triple positive breast carcinomas. Such tumours are more likely ALN positive than those with another steroid receptor and HER-2 status. How these findings correlate with breast cancer prognosis remains to be investigated