Clinical outcome of adjuvant endocrine treatment according to PR and HER-2 status in early breast cancer

Patients with estrogen receptor (ER)+/progesterone receptor (PR)- and/or HER-2 overexpressing breast carcinomas may derive lower benefit from endocrine treatment. We examined retrospectively data from 972 breast cancer patients who received tamoxifen (725), tamoxifen + Gn-RH analogs (127) and aromatase inhibitors (120) as adjuvant treatments. ER+/PR- versus ER+/PR+ tumours were characterised by larger size (P = 0.001), higher tumour grade (P = 0.001), higher Ki-67 expression (P = 0.001) and lower mean ER (P = 0.000) and HER-2 expression (P = 0.000). At univariate analysis, tumour grading [hazard ratio (HR) = 4.0; 95% confidence interval (CI) = 1.4-11.1; P = 0.007], nodal status (HR = 3.4; 95% CI 1.2-5.7; P = 0.000), tumour diameter (HR = 2.9; 95% CI 1.7-4.7; P = 0.000) lack of PR expression (HR = 2.1; 95% CI 1.3-3.4; P = 0.002) and HER-2 overexpression (HR = 1.9; 95% CI 1.0-3.5; P = 0.03), as well as Ki 67 expression (HR = 1.7; 95% CI 1.0-2.7; P = 0.04) were associated with shorter disease-free survival (DFS). At the multivariate analysis, nodal status (HR = 3.6; 95% CI 1.9-6.8; P = 0.0001), lack of PR expression (HR = 2.3; 95% CI 1.3-4.0; P = 0.003) and tumour diameter (HR = 2.1; 95% CI 1.1-3.8; P = 0.018) retained their prognostic significance, whereas HER-2 overexpression was associated with a trend towards shorter DFS that was of borderline statistical significance (HR = 2.0; 95 % CI 1.0-3.9; P = 0.05). Our data suggest that lack of PR expression and HER-2 overexpression are both associated with aggressive tumour features, but the prognostic information of PR status on the risk of recurrence in endocrine-treated breast cancer patients is stronger.