We, therefore, assume that our findings can also be applied to patients who receive current standard care and this could in the future be addressed by analysing studies like the NSABP B-14 trial.38 For premenopausal patients, the most recent ASCO guideline recommends offering adjuvant tamoxifen for at least 5 or even 10 years.40 We demonstrated that the absence of activated PI3K/MAPK pathways in the primary tumour was predictive for substantial tamoxifen benefit in postmenopausal patients. This evidence concerns the gene PIK3CA and neoplasm.