E25: Is adjuvant chemotherapy being overused or underused in women aged < 50 with HR+ HER2- breast cancer in the National Cancer Database?

ePoster Abstract Author(s)

Susan J. Doh, MD (she/her/hers)

Resident
Division of Surgical Oncology, Department of Surgery, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, OH, USA
Cleveland, Ohio, United States

Submitter(s)

Susan J. Doh, MD (she/her/hers)

Resident
Division of Surgical Oncology, Department of Surgery, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, OH, USA
Cleveland, Ohio, United States

Author(s)

Susan J. Doh, MD (she/her/hers)

Resident
Division of Surgical Oncology, Department of Surgery, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, OH, USA
Cleveland, Ohio, United States
AA

Amanda L. Amin, MD, MS, FACS, FSSO

Section Chief, Breast Surgery, Co-Director, Breast Cancer Program, UH Seidman Cancer Center
Division of Surgical Oncology, Department of Surgery, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, OH, USA, United States
AS

Ashley B. Simpson, DO, FACOS, FACS

Clinical Assistant Professor, Case Western Reserve University School of Medicine
Division of Surgical Oncology, Department of Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA, United States
LR

Lisa Rock, MD, FACS

Clinical Instructor, Case Western Reserve University School of Medicine
Division of Surgical Oncology, Department of Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA, United States
RS

Robert Shenk, MD

Associate Professor, Case Western Reserve University School of Medicine
Division of Surgical Oncology, Department of Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA, United States
MM

Megan Miller, MD, FACS

Assistant Professor, Case Western Reserve University School of Medicine
Division of Surgical Oncology, Department of Surgery, University Hospitals Cleveland Medical Center, Cleveland, OH, USA
Cleveland, Ohio, United States

Introduction: For HR+ HER2- breast cancer, the TAILORx and RxPONDER studies established the benefit of adjuvant chemoendocrine therapy over endocrine therapy alone in women aged ≤50 with N0 disease and OncotypeDx recurrence score (RS) 16-25, and N1 disease and RS < 25, respectively. Our aim was to determine factors associated with chemotherapy receipt in women < 50 with stage I-III HR+ HER2- breast cancer in clinical practice and assess overall survival (OS) for comparison with clinical trials data.

Methods: We queried the NCDB 2004-2020 for women aged 18-49 with stage I-III HR+ HER2- breast cancer who underwent surgery. Patients with inflammatory breast cancer, bilateral disease, unknown RS, and neoadjuvant systemic therapy receipt were excluded. Univariable logistic regression and multivariable Cox proportional hazards assessed factors associated with chemotherapy receipt and OS.

Results: Of 69,542 patients, 82.5% were pN0, 17.3% were pN1, and 0.1% were pN2+. RS was similar in pN0 and pN1 patients: low RS (0-10) 19.7% and 19.4%, intermediate RS (11-25) 66.8% and 67.3%, and high RS ( >25) 13.6% and 13.3%. Chemotherapy receipt increased with greater burden of nodal disease (24.1% pN0, 46.8% pN1, and 88.1% pN2+, p< 0.001) and with RS (4.9% low, 56% intermediate, 39% high, p< 0.001). The vast majority of pN0 patients who received chemotherapy had RS 16-25 (46.7%) or >25 (44.9%). However, in the N0 group, 68.6% of RS 16-25 and 15.1% of RS >25 patients did not receive chemotherapy. Of pN1 patients, 70.5% of low RS and 52.6% of intermediate RS patients did not receive chemotherapy. Factors positively associated with chemotherapy receipt were intermediate and high RS (OR 4.04 and OR 57.17, both p < 0.001), grade 3 histology (OR 3.66, p < 0.001), larger tumors (pT2-4 OR 1.48-3.07, p < 0.001), and nodal positivity (pN1 OR 3.17 and pN2+ OR 12.29, both p < 0.001). For patients who received endocrine therapy (n = 65,238, 93.8%), there was an OS benefit with chemoendocrine therapy in pN0 patients with RS 16-25 (HR 0.75, p=0.031). A similar OS advantage was observed for pN1 patients with intermediate (HR 0.65, p=0.006) and high RS (HR 0.4, p=0.02).

Conclusions: Acknowledging the exclusion of neoadjuvant treatment, less than half of women with HR+ HER2- breast cancer aged < 50 and pN0 RS 16-25 or pN1 RS < 25 in the NCDB received adjuvant chemoendocrine therapy despite the OS benefit established in clinical trials and largely confirmed in this study. Our results likely reflect complex decision-making, including the potential replacement of chemotherapy with ovarian suppression, and highlight opportunities to refine application of the recent TAILORx and RxPONDER findings to oncologic practice.

Learning Objectives:

Identify whether chemoendocrine therapy is being overused or underused in women aged <50 with HR+ HER2- breast cancer in the NCDB based on nodal status, OncotypeDx score, and OS benefit
Describe factors associated with chemotherapy receipt in this population
Compare overall survival in the NCDB cohort vs. TAILORx and RxPONDER clinical trials