Patients with PR-negative tumours consistently have a poorer prognosis than those with PR+ tumours,51 regardless of adjuvant endocrine agent taken.6–8 We also found that patients with tumours that were PR-negative by immunohistochemistry had a poorer prognosis, but the level of ER:PR-B interactions was more prognostic for relapse. Here, PGR is linked to neoplasm.