The discussion opens with an overview of the evolving treatment landscape for patients with high-risk HR-positive/HER2-negative early breast cancer, highlighting how adjuvant CDK4/6 inhibitors have expanded treatment options beyond endocrine therapy alone. The faculty review the evidence supporting these agents and discuss how clinical trial eligibility criteria from monarchE and NATALEE inform treatment selection in routine practice. Particular attention is given to assessing recurrence risk using factors such as nodal involvement, tumor size, grade, and other clinicopathologic features while recognizing that many patients do not fit neatly within trial-defined populations. The conversation also addresses the challenges clinicians face when applying study criteria to real-world cases and emphasizes the importance of individualized decision-making. Practical considerations surrounding node-positive and selected node-negative disease are explored as the panel discusses how recurrence risk ultimately guides recommendations for adjuvant CDK4/6 inhibitor therapy.

This segment focuses on the practical considerations surrounding the initiation of adjuvant CDK4/6 inhibitor therapy after surgery and other planned treatments. The faculty discuss how chemotherapy, radiation therapy, endocrine therapy, and ovarian suppression influence treatment sequencing and timing in everyday practice. They review the timing windows established in the monarchE and NATALEE clinical trials and consider how these data can be applied when patients experience delays or require individualized treatment schedules. The conversation also highlights the importance of patient education before treatment begins, ensuring that patients understand the overall treatment plan and expectations for long-term therapy. Looking ahead, the panel examines ongoing research evaluating chemotherapy de-escalation and the potential role of genomic risk assessment in guiding treatment decisions. The discussion concludes with consideration of how treatment sequencing may affect patient adherence and persistence with adjuvant therapy over time.

This segment turns to the clinical trial evidence supporting adjuvant CDK4/6 inhibition, with the faculty examining invasive disease-free survival outcomes from monarchE and the consistency of benefit across clinically relevant subgroups including menopausal status, tumor size, tumor grade, and nodal burden. The panel discusses how extended follow-up has reinforced confidence in these agents, noting that the separation between treatment curves has been sustained beyond the completion of therapy, and considers what additional long-term data may bring for ribociclib. The conversation then shifts to the challenge of framing risk and benefit in a curative-intent population, where patients are typically asymptomatic and may question the need for further treatment after surgery. The faculty emphasize patient education around the rationale for adjuvant therapy and the goal of preventing distant recurrence. The segment closes with a candid exchange on treatment discontinuation, contrasting rates reported in clinical trials with real-world experience and underscoring the role of attentive clinical follow-up and dose adjustment in keeping patients on therapy.

The faculty explore the practical and logistical dimensions of delivering adjuvant CDK4/6 inhibitor therapy, including prescribing, care team coordination, and the identification of patients at higher risk of non-adherence. The discussion highlights the contributions of pharmacists, nurses, and advanced practice providers in patient teaching and early follow-up, as well as strategies for synchronizing laboratory monitoring and injections to minimize clinic burden for patients returning to work and daily life. Attention then turns to the principal toxicities associated with these agents, including gastrointestinal effects with abemaciclib, neutropenia across the class, and hepatic enzyme abnormalities associated with ribociclib. The panel reviews approaches to monitoring and management, including the use of a stepwise dose escalation strategy at initiation and the role of dose reduction in improving tolerability without presumed loss of efficacy. The conversation closes by considering how evolving genomic data may lead to more patients receiving endocrine therapy and CDK4/6 inhibition without chemotherapy.

The faculty present the first case, a premenopausal woman with hormone receptor-positive, HER2-negative breast cancer who received neoadjuvant chemotherapy and was found to have residual invasive disease with multiple involved nodes, high-grade histology, and an elevated proliferation index.

Continuing with the first case, the faculty consider how to choose between abemaciclib and ribociclib for a patient who clearly meets monarchE eligibility, discussing the influence of longer follow-up and available survival data alongside comorbidities such as underlying gastrointestinal issues.

The second case introduces a postmenopausal woman with a moderately sized, intermediate-grade tumor and limited nodal involvement who completed adjuvant chemotherapy and radiation and presents several months after surgery, already established on endocrine therapy and hesitant to add further treatment because of toxicity concerns.

The closing segment focuses on shared decision-making for patients balancing a desire to reduce recurrence risk against concerns about quality of life during years of therapy.