P6: Short-term outcomes in DCIS patients managed without initial surgery

Thursday, March 23, 2023

2:51 PM – 2:56 PM

Location: SSO HUB: Breast & Endocrine Zone

Poster Presenter(s)

Amanda L. Nash, MD

Resident
Duke University School of Medicine
Durham, North Carolina, United States

Disclosure information not submitted.

Author(s)

Amanda L. Nash, MD

Resident
Duke University School of Medicine
Durham, North Carolina, United States

Disclosure information not submitted.
YR

Yi Ren, MS

Biostatistician III
Duke Cancer Institute, Duke University Medical Center, Durham, NC, United States

Disclosure information not submitted.
ST

Samantha M. Thomas, MS

Biostatistician
Biostatistics and Bioinformatics, Duke University, United States

Disclosure information not submitted.
AF

Amanda B. Francescatti, MS

Cancer Surgery Standards Program
American College of Surgeons, United States

Disclosure information not submitted.
AM

Anne McCarthy, n/a

Program Manager
Cancer Programs, American College of Surgeons, Chicago, IL, United States

Disclosure information not submitted.
TL

Thomas Lynch, MD

Clinical Associate
Division of Surgical Sciences, Department of Surgery Duke University Medical Center, Durham, NC, United States

Disclosure information not submitted.
EF

Elizabeth Frank, n/a

Patient Advocate
Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, United States

Disclosure information not submitted.
AP

Ann Partridge, MD, MPH

Professor of Medicine, Chair in Breast Cancer Research
Dana Farber Cancer Institute, United States

Disclosure information not submitted.
Alastair Thompson, BSc (Hons), MBChB, MD

Olga Keith Wiess Professor of Surgery, Chief of Section and Co-lead of the Lester and Sue Smith Breast Center
Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine
Houston, Texas, United States

Disclosure information not submitted.
LG

Lars Grimm, MD

Assistant Professor
Duke University Hospital, United States

Disclosure information not submitted.
tH

terry Hyslop, PhD

Professor of Biostatistics
Jefferson Sidney Kimmel Cancer Center, United States

Disclosure information not submitted.
Shelley Hwang, MD MPH

Vice Chair of Research, Chief of Breast Surgical Oncology
Duke University
Durham, North Carolina, United States

Disclosure information not submitted.
MR

Marc Ryser, PhD

Assistant Professor in Population Health Sciences
Duke Cancer Institute, Department of Population Health Sciences, Department of Mathematics, United States

Disclosure information not submitted.

Introduction: The trade-offs of an active monitoring (AM) strategy for DCIS, with surgery only upon disease progression, are an area of active investigation. More evidence is needed to determine the feasibility and safety of this approach. We compared follow-up burden and cancer outcomes in women diagnosed with low-risk and high-risk DCIS who were managed without upfront surgery.

Methods: A stratified random sample of patients with DCIS who did not receive surgery within 6 months of diagnosis was selected from 1,330 Commission on Cancer-accredited sites. Data were abstracted from primary source documentation at each site, including subsequent biopsies, first surgery, and cancer diagnoses for up to 10 years. Low-risk disease (DCIS or invasive) was defined as grade I/II and hormone receptor (HR) positive tumors diagnosed at age ≥40; all others were considered high-risk. Invasive cancer subtype was defined by HR and HER2 status. Number of biopsies, first surgery, and risk status and subtype of subsequent invasive cancers were compared between DCIS risk groups using Chi square tests.

Results: 1,905 patients were included, with a median follow up of 46.7 months (IQR 28.4-72.6). 251 (13.2%) women received at least one subsequent biopsy, and 759 (39.8%) went on to have breast surgery (Table 1). Type of surgery differed by DCIS risk group (p < 0.001). Among the 109 locoregional invasive events, and excluding unknowns, the risk group concordance between index DCIS and subsequent invasive cancer was 75.9%. The subtype of subsequent invasive cancers differed by DCIS risk status (p=0.003), with 82.1% of low-risk patients diagnosed with HR-positive, HER2-negative disease.

Conclusions: During short term follow-up, women without initial surgery for DCIS had a low biopsy burden and the majority did not receive surgery. Compared to low-risk patients, high-risk patients had more extensive surgery and a less favorable invasive cancer phenotype on progression. These findings support that high-risk DCIS is not suitable for AM. Among patients with low-risk DCIS, such evidence will help patients weigh the burdens and benefits of AM, including the need for close monitoring to identify early disease progression.

Learning Objectives:

define low-risk DCIS
describe how first surgery differs between low-risk and high-risk DCIS patients
describe how risk of invasive progression differs between low-risk and high-risk DCIS