Current treatment landscape of HR+/HER2- advanced breast cancer in the Nordics: a modified Delphi study

This Delphi study aimed to assess current perspectives on hormone receptor-positive/human epidermal growth factor receptor 2-negative(HR+/HER2-) advanced breast cancer (aBC) treatment strategies across the Nordics, and to establish where consensus exists across the Nordics on HR+/HER2- aBC treatment.

A modified, three-round Delphi method was followed. A steering committee was appointed for study coordination, panellist selection, and questionnaire development. The questionnaires covered relevant topics on HR+/HER2- aBC treatment: treatment patterns in different lines of therapy (first [1L], second [2L], and third [3L]), oligometastatic disease, de novo aBC, brain metastases, age as influential factor, visceral crisis, radiotherapy, diagnostics, and clinical guidelines. Both open and closed-ended questions were included. Consensus was defined as at least 70% agreement.

In total, 28 experienced BC oncologists participated in the study from all five Nordic countries. Overall, topics reaching consensus included: preferred treatment approach in 1L and 2L therapy, treatment of oligometastatic disease, visceral crisis, brain metastases, and age-related treatment considerations. No consensus was reached for 3L therapy and local treatment for primary tumour in de novo aBC. Endocrine therapy (ET) combined with a cyclin-dependent kinase (CDK)4/6 inhibitor was the treatment of choice for 1L and 2L therapy. Treatment patterns in clinical practice did not always follow recommendations in current Nordic guidelines, as seen in the case of recently approved treatments.

ET in combination with a CDK4/6 inhibitor is the preferred frontline treatment for HR+/HER2- aBC in the Nordics. The observed discrepancy between current guidelines and clinical practice could be due to differences in the reimbursement of novel treatments in the Nordics. Collaborative research efforts are warranted for topics that lack consensus.