BACKGROUND:This study normalized the National Cancer Database (NCDB) and Surveillance, Epidemiology, End Results Program (SEER) populations to mirror the USCS population and examined survival outcomes in breast cancer following normalization. METHODS:Patients diagnosed with stage I-IV breast cancer (2010-2018) were selected from the NCDB and SEER. Rates obtained from the USCS were used to normalize the NCDB and SEER cohorts, using patient weighted frequencies for variables (age, sex, race/ethnicity, etc). Overall survival was estimated using the Kaplan-Meier method before and after normalization. RESULTS:The USCS included 2473,739 patients, the NCDB 1441,556, and SEER 504,938. There were minimal differences between the cohorts based on age or sex. There were notable differences in the racial/ethnic composition (Hispanic: USCS 8.3 %, NCDB 5.9 %, SEER 11.7 %; p < 0.001). There were minimal differences in tumor biomarkers, but significant differences in extent of disease (local: USCS 66.1 %, NCDB 80.2 %, SEER 68.4 %; distant: USCS 6 %, NCDB 3.9 %, SEER 3.9 %; p < 0.001). Variables that were similar without weighting (age, sex, tumor biomarkers), had similar OS after weighting. However, when the NCDB and SEER were weighted by stage, HR status and race/ethnicity combined, slight changes were seen in 5-year OS (NCDB regional: unweighted 76.8 % vs weighted 77.0 %, SEER regional: unweighted 79.7 % vs weighted 78.5 %; p < 0.001). CONCLUSIONS:US tumor registries provide data for a large sampling of breast cancer patients. Despite significant differences in case coverage based on race/ethnicity and stage, OS remained similar following normalization to the USCS, suggesting that analyses using these data sets may be generalizable to the population.

Background: Young women with early-stage breast cancer are increasingly choosing contralateral prophylactic mastectomy (CPM) despite longstanding data demonstrating that breast conservation is equally effective as mastectomy, with comparable overall and disease-specific survival. Life-stage specific factors (e.g., breastfeeding, body image) can make surgical decisions particularly complex for young women and young women report high levels of decisional conflict regarding the surgical decision. The use of decision support tools has been shown to improve decision quality and reduce decisional regret. To optimally support young women making decisions about breast cancer surgery, we developed CONSYDER, a web-based decision aid (DA) tailored to the unique concerns of young patients. We aimed to test the effectiveness and implementation of the DA in a multi-center, pragmatic trial. Methods: The CONSYDER Study incorporates a Type II hybrid effectiveness-implementation, stepped-wedge design. Using a mixed-methods approach, including surveys, interviews, focus groups, and audio-recordings with patients and providers, we will test the efficacy and evaluate the implementation of the CONSYDER DA across 4 sites (Weill Cornell Medicine, Yale Cancer Center, Dana-Farber Cancer Institute, Duke Cancer Institute) over a 30-36 month period. Eligibility criteria include: female and age 18-44 years with a new diagnosis of stage 0-III unilateral breast cancer. All sites have a 6-month “run-in” period (T1) where patients will not be sent the DA. Sites will then be randomized to begin delivery of the DA as part of standard clinical care during subsequent 6-month blocks (T2, T3, T4, or T5). The primary study aims are to: 1) test the effectiveness of the DA on reducing patient-reported decisional conflict (assessed by the Decisional Conflict Scale [DCS]) prior to breast cancer surgery; 2) evaluate the implementation and mechanisms of DA use. Secondary aims include determining the impact of the DA on decision-making preferences, breast cancer knowledge, treatment goals and preferences, anxiety, decisional regret, and self-efficacy in communication. An exploratory aim will evaluate how the DA impacts surgical choice. A sample size of 800 patients (200 per site) was selected to have approximately 80% power to detect a minimum effect size of 0.35 (clinically meaningful DCS effect sizes range 0.3 to 0.4). For the primary endopoint, we will use generalized linear models to assess if the DCS score differs between the intervention and usual care groups. An assessment for differential effects of the DA on women of different races, ethnicities, and ages (e.g., 40-44 vs. 35-39 vs. <35) will be performed by testing for a treatment by variable (e.g., race, ethnicity, age group) interaction, assuming sufficient accrual numbers for different patient subsets. As part of the implementation evaluation, we will perform semi-structured interviews with a subset of participants. Surgeon attitudes and approaches around discussing surgical options will be evaluated with a survey of surgeons prior to the implementation of the DA and at the end of the study. To complement the surgeon surveys, we will randomly sample a subset of surgeons at each site post-implementation and audio-record 4-8 consultations per surgeon to characterize how the DA may impact patient-provider communication and shared surgical decisions. We will also conduct interviews and focus groups with providers/staff involved with the delivery of the DA about perceived barriers to DA implementation at their site/practice and opportunities to improve sustainability. The CONSYDER Study opened to enrollment in March 2024. As of June 2024, 57 participants are enrolled. Clinical Trials Information: NCT06275126 Citation Format: Shoshana Rosenberg, Yushu Shi, Anna Revette, Lindsay Northrop, Laura Dominici, Jennifer K. Plichta, E. Shelley Hwang, Karen Sepucha, Maryam Lustberg, Lisa Newman, Ann H. Partridge, Rachel A. Greenup. Effectiveness and implementation of a decision support tool to improve surgical decision-making in young women with breast cancer: The CONSYDER Study [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P2-08-22.

Background: Despite improvement in survival rates over time, recurrence and treatment-related adverse events remain concerning risks for patients with early (stage I-III) breast cancer (eBC). The EVOLVE Registry, a patient-centered United States (US)-based registry was created to address the limitations of existing eBC databases and better understand real-world sociodemographics, clinical characteristics, diagnostic and treatment pathways, clinical outcomes, and patient experience in eBC. This is the first analysis of the ongoing EVOLVE Registry. Methods: The EVOLVE Registry, created through a collaboration between PicnicHealth and AstraZeneca, consists of the de-identified medical record data, along with patient-reported social determinants of health (SDoH) and patient-reported outcomes (PROs) data. Inclusion criteria were defined as eBC (invasive, non-metastatic) diagnosed ≤3 years prior to enrollment and ≥18 years old at consent. Patient enrollment began May 2023. Using PicnicHealth’s platform, all available retrospective medical records prior to enrollment, including pre-diagnosis, were retrieved. Following enrollment, medical records and survey/PRO were prospectively collected. eBC-specific data elements were abstracted from structured and narrative text. Rural/urban categorization was derived from Rural-Urban Commuting Area (RUCA) codes. While enrollment (target: 3,000 patients) and data collection is ongoing, data from medical records collected and completed surveys for patients enrolled in the EVOLVE Registry up to June 2024 were analyzed. Patient demographics, receptor status, and self-reported SDoH data are described. Results: A total of 1,428 patients with eBC enrolled as of June 2024 with a median of 7 years of visits pre-diagnosis and 2 years of visits post-diagnosis. Mean (range) age at diagnosis was 55 (24 - >89) years, with 76% diagnosed between 40-69 years and 35% diagnosed ≤1 year of enrollment. Almost all patients (n=1,427) were female; 77% were White, 12% Black/African American, 2% Asian, 4% mixed race, and 5% other race; 13% were Hispanic/Latino; 93% resided in a metropolitan/micropolitan area and 7% small town/rural. Most patients had hormone receptor (HR)+/human epidermal growth factor receptor 2 (HER2)- eBC (70%), followed by 15% HR-/HER2-, 11% HR+/HER2+, 4% HR-/HER2+, and 1% unknown. About half (55%) were diagnosed at stage I, 32% at stage II, and 13% at stage III. Of the 58% of patients who responded to the SDoH survey, 98% had some form of medical insurance; 20% had a high school education or less; 31% had full time employment, 10% part-time employment, and 27% were retired; 62% reported a household annual income of <$75k; 57% owned their own housing; 25% were concerned about losing their housing; 16% reported lack of transportation access kept them from medical appointments. 47% reported current or former use of nicotine-based products, 89% of whom reported cigarette use and 25% reported e-cigarette/vape use. Conclusions: The EVOLVE Registry to date has enrolled a population broadly representative of patients with eBC in the US with regards to race, ethnicity, and eBC characteristics. The patient-reported SDoH indicated a highly insured population, however, this may not reflect financial burden and unmet needs, including for transportation and housing security, as those were still apparent in this population. With ongoing enrollment, this registry will help further the understanding of the evolving real-world treatment of eBC, existing disparities, and patient needs across diagnostic and treatment pathways that affect breast cancer outcomes. Citation Format: Haley S. Friedler, Michael C. S. Bissell, Kellie Ryan, Michele Baber, Xiaoqing Xu, Zulikhat Segunmaru, Chintal H. Shah, Qixin Li, Thomas Quinn, Amy Longenecker, Amy Bryer, Colleen Goldberg, Gillian Hanson, Maryam Lustberg, Maryam Lustberg, N Lynn Henry, Rachel A Greenup, Mariana Chavez-MacGregor, Joseph M. Unger, Alice Ho, Deborah Collyar, Miranda Gonzales, Tiffany Haynes, Josefa Briceno. Preliminary Analysis of Sociodemographic and Clinical Characteristics of Patients with Early Breast Cancer in the Patient-Centered, Real-World EVOLVE Registry [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P1-10-11.

Increasing incidence of breast cancer among young adults (YA), defined by the National Comprehensive Cancer Network (NCCN) as age < 40 years, has amplified concerns over financial toxicity (FT) in this demographic. This systematic review sought to clarify the association between YA status and FT. We queried bibliographic databases for full-text English language publications between 2010 and 2024 reporting FT using validated patient-reported outcome metrics among patients with stage I–III breast cancer. Two reviewers screened and extracted data between June and September 2024. Variables of interest included age and treatment-related adverse events (secondary outcome of interest). Of 4023 articles screened, 66 were included for review. Sixty-four were excluded for including in situ or metastatic disease, multiple cancer histologies, or FT as a parameter of a larger scale without validation for stand-alone use. While no studies compared FT using the NCCN YA threshold (i.e., < 40 versus ≥ 40 years), two studies demonstrated that younger age was associated with worse FT. One study compared patients age ≥ 65 to < 65 years using the Comprehensive Score for Financial Toxicity, and the other considered age as a continuous variable using the Psychological Sense of Economic Hardship Scale. The latter also reported treatment-related symptoms were associated with greater FT after adjusting for age. No study identified the multidimensional domain of FT as a primary outcome among YA versus non-YA women with non-metastatic invasive breast cancer. Two studies showed younger age was associated with greater FT. As FT has been shown to negatively impact patient outcomes, further investigations are needed to support policy efforts and to improve care for younger breast cancer survivors.

Background: Approximately 20% of patients report inadequate discussions with their providers about reconstructive options, with an increased frequency reported in non-White women. Eliciting treatment preferences with adaptive choice-based conjoint (ACBC) analysis can improve our understanding of what patients’ value. We aimed to determine what African American (AA) patients value when considering breast reconstruction options. Methods: Cross-sectional ACBC with AA women considering breast reconstruction recruited through community partnerships and an academic medical center. Relative importance scores, part-worth utilities, and maximum-acceptable risks were calculated to assess preferences for attributes of flap versus implant reconstruction. Results: Overall, 181 women, 101 from an academic center and 80 from the community were included. The most important attributes were risk of complications [mean (SD) relative importance (RI), 26% (12%)], additional surgeries [RI, 24% (14%)], and abdominal morbidity [RI, 22% (11%)]. Women were least concerned with appearance [RI, 15% (12%)] and recovery time [RI, 14%, (10%)]. Fewer women preferred a profile representing flap (n=27, 15%) compared to implant reconstruction (n=154, 85%). Those who preferred flap reconstruction cared most about additional surgeries [RI, 36% (15%)]; in contrast, those who preferred implant reconstruction cared most about complications [RI, 27% (12%)]. Participants with fewer comorbidities [OR, 0.84; p=0.012], no prior surgical complication (OR, 0.32; p=0.029), and prophylactic mastectomy (OR, 6.07; p=0.19) were more likely to choose the implant profile. Conclusion: AA patients place greatest value on minimizing complication risk and additional surgeries when considering post-mastectomy reconstruction. Future studies should assess how eliciting individual-level preferences can improve shared decision-making in surgery.

Introduction: Home recovery (HR) after mastectomy promotes faster recovery and may improve patient experience. We examined the cost differences after mastectomy, comparing same day mastectomy discharge to inpatient admission amoung commercially insured women. Methods: Merative MarketScan Commercial and Medicare Databases (2017-2019) were used to identify women ≥18 years old who underwent mastectomy. Mastectomy encounters were classified as home recovery (stays spanning a single calendar date) or inpatient stay (stays >1 calendar day) based on the length of the visit. Total payments (from both patients and insurers) for the mastectomy encounter were calculated by summing all paid claims falling within the start and end dates of the encounter. Payments were also summed separately for professional versus facility claims, and by patient versus insurer payments. Median costs were calculated stratified by home recovery status, and calculated by various encounter characteristics, such as patient region and occurrence of simultaneous breast reconstruction. Medians were compared between home recovery groups using rank-sum tests. Results: Of 11,508 patients undergoing mastectomy, 4,683 (40.7%) were HR patients while 6,825 (59.3%) underwent hospital admission. Mean age of HR patients was 53.6 yo while admission patients was 51.8 yo (p<0.001). The mean length of stay for the inpatient group was 2.3 days. Overall, median total costs were significantly lower among women who underwent HR when compared to hospital admission ($23,173 vs $33,901, p<0.001); facility costs also differed ($16,721 vs $23,539, p<0.001) as well as professional surgical cost ($6,441 vs $7,962, p<0.001). The median cost difference was also present with simultaneous non-autologous reconstruction ($35,739 vs $41,028, p<0.001). Geographical location also affected median surgical costs: Northeast ($29,327 vs $41,233, p<0.001), North Central ($18,739 vs $28,455, p<0.001), South ($11,911 vs $32,819, p<0.001), and West ($23,912 vs $36,790, p<0.001). HR after mastectomy remained less costly than hospital admission regardless of Medicare ($7,322 vs $18,072, p<0.001) vs commercial insurance ($26,269 vs $34,691, p<0.001). The median 1-year all healthcare cost is less in the outpatient mastectomy group compared to admission group ($34,748 vs $38,410, p<0.001). Conclusion: Following mastectomy, Home Recovery is associated with significantly lower costs when compared to hospital admission regardless of geographical region, simultaneous reconstruction, and insurance coverage. With fewer costs, faster recovery, and improved patient satisfaction, home recovery after mastectomy is a clinically and financially non-inferior alternative to conventional inpatient admission for the appropriate patient population. Citation Format: Leah Kim, Miranda Moore, Rachel Greenup, Donald Lannin, Tristen Park. Cost Differences of Hospital Admission vs. Home Recovery following Mastectomy [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2024; 2024 Dec 10-13; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(12 Suppl):Abstract nr P3-07-09.

Purpose Postmastectomy immediate breast reconstruction (PMIBR) rates in breast cancer patients have increased over recent decades but remain less frequently performed and understudied in elderly patients. We aim to evaluate postmastectomy breast reconstruction trends by age in Korea and the United States, highlighting potential disparities related to age, geography and ethnicity. Methods This is a multi-cohort retrospective study analyzing three databases. The Asan Medical Center-Breast Cancer Registry (AMC-BCR) included 13,654 total mastectomy patients from 2001–2021. A subset of patients, separately collected as AMC-plastic surgery registry (AMC-PSR) was used to analyze age-related differences in comorbidities and complications. The National Cancer Database (NCDB) included 966,354 total mastectomy patients with stage 0–3 breast cancer from 2004–2020. Results PMIBR rates in AMC-BCR increased from 13–78% in younger patients (< 60 years) and from 0–28% in older patients (≥ 60 years). Patients living in a metropolitan area (49.4% vs. 46.6%, p = 0.001), with higher education (93.2% vs. 66.3%, p < 0.001), unmarried (12.5% vs. 5.1%, p < 0.001), and with no childbirth history (10.5% vs. 6.3%, p < 0.001) were more likely to undergo reconstruction. In the NCDB, the rates were 37% for young (< 60) Asian-Americans, 48% for young non-Asians, 14% for older (≥ 60) Asian-Americans, and 24% for older non-Asians in 2020. Asian-Americans had the lowest reconstruction rates across ethnicities. AMC-PSR data showed no significant difference in major complications by age. Conclusions Older patients exhibited lower reconstruction rates than the younger patients and demographic factors differed between age groups, suggesting disparities by age, ethnicity and cultural factors.

e23194 Background: Financial toxicity (FT), the detrimental effect of treatment-related expenses on patient outcomes, is a significant issue related to breast cancer diagnosis and treatment. The rising incidence of breast cancer among young adults (YA) age ≤ 40 has amplified concerns over FT in this demographic. Despite this, the degree to which YA status impacts FT is unclear. This systematic review sought to clarify the association between age and FT as a first step in understanding how FT may affect age-based health disparities. Methods: This systematic review queried PubMed, Embase, Web of Science, Sociological Abstracts, PsychINFO, CINAHL, and EconLit for full-text English language articles published between 2010-2024 reporting FT using validated patient-reported outcome metrics among patients with stage I-III breast cancer. Given that FT is a multidimensional construct, studies that assessed cancer-related costs alone without consideration for financial hardship, distress, or anxiety were excluded. As chemotherapy, a primary driver of cancer-related costs, is not routinely indicated for stage 0 disease, studies incorporating these patients were excluded. Two independent reviewers screened and extracted data between June-September 2024. Variables of interest included age and treatment-related adverse events. Quality was assessed using National Heart, Lung, and Blood Institute assessment tools. Results: Of 4,023 articles screened, 66 were included for full text review. Sixty-four were further excluded for including in situ or metastatic disease, multiple cancer subtypes, or if FT was assessed as a parameter of a larger scale without published precedent for stand-alone use. While no studies compared FT among YA versus non-YA women, the two remaining studies demonstrated that younger age was associated with worse FT. One of these compared those ≥65 to < 65 years old using the COST scale and the other considered age as a continuous variable and assessed FT using The Psychological Sense of Economic Hardship Scale. The latter also found that symptoms of breast cancer or its treatment were associated with greater FT after adjusting for age. Conclusions: In this systematic review, no study identified the multidimensional domain of FT as a primary outcome among YA versus non-YA women with non-metastatic invasive breast cancer. Although limited, two studies did show younger age to be associated with greater FT. Inconsistencies in age classification, use of validated outcome metrics, and criteria for FT limit our current understanding of how FT impacts YA with breast cancer. Further investigations exploring age as a social determinant of health are needed to support policy efforts that prevent sub-optimal outcomes for younger patients, including deviations from standard treatment related to affordability of care.

Advances in contemporary breast cancer care (e.g., early detection, increased use of preoperative chemotherapy, and updated SSO–ASTRO margin guidelines) have the collective potential to influence successful breast conservation. We evaluated contemporary trends in conversion to mastectomy (lumpectomy followed by definitive mastectomy) among women with breast cancer undergoing initial lumpectomy. Women with unilateral clinical stage 0–III breast cancer were identified from the National Cancer Database (2009–2019). Treatment sequence was categorized into surgery first or neoadjuvant chemotherapy (NACT) followed by surgery. We used a multivariable logistic regression model to calculate the predicted probability of conversion to mastectomy across diagnosis year and race and ethnicity, controlling for socio-demographic and clinical factors. We then calculated the relative change in conversion to mastectomy over time for each race and ethnic group. The study included N = 1,543,702 women. Approximately 9.2

Studies show that Medicaid expansion leads to timely diagnosis and treatment of early-stage breast cancer; however, no studies have examined its impact on locally advanced breast cancer (LABC). We assessed LABC rates pre- and post-Medicaid expansion, and evaluated overall survival (OS) in LABC patients treated in expansion and non-expansion states. Overall, 5147 National Cancer Database participants age 40–64 years diagnosed with LABC between 2010 and 2017 were allocated into the two cohorts. Demographic/clinical variables were compared using the Wilcoxon rank-sum and Pearson’s Chi-square tests. A generalized linear model assessed trends in LABC diagnoses over time, while a Cox proportional hazards model evaluated associations between Medicaid expansion status and OS. A total of 3346 and 1801 LABC patients resided in expansion and non-expansion states, respectively. Ninety-one percent of non-expansion patients resided in the Southern United States (p < 0.001) versus 8.2

Background: While survival for patients with early breast cancer (eBC) has greatly improved with earlier detection and modern treatments, the risk of recurrence and long-term/late treatment-related adverse events (AEs) remain concerns for many patients. Contemporary real-world data are needed to understand current diagnostic pathways, treatment patterns and toxicities, quality of life, and patient experience to better characterize eBC care and knowledge gaps and establish important hypotheses to test in prospective trials, with the ultimate goal to improve both treatment and outcomes for patients with eBC. Study design: PicnicHealth and AstraZeneca are collaborating to build a real-world observational eBC cohort composed of de-identified medical records data supplemented with patient-reported outcomes (PROs), including patient-reported social determinants of health (SDoH). Patients recruited from multiple channels, such as digital marketing and community partnerships, will consent to participate and sign HIPAA authorization for PicnicHealth to collect their medical records from all providers and sites of care in the United States. All available retrospective medical records in any format will be retrieved, and records will continue to be collected for patients prospectively following enrollment. Disease-specific information will be abstracted using PicnicHealth’s human-in-the-loop machine learning abstraction platform. Patients will have access to their records in the form of a searchable and shareable digital timeline. Additional data, including but not limited to symptoms, quality of life and treatment experience will be collected through surveys. The first patient was enrolled in May 2023. Patients will be followed for ≥8 years or until withdrawal or death, whichever occurs first. Eligibility criteria: Patients with stage I-III breast cancer diagnosed ≤3 years before enrollment, who onboard to the PicnicHealth platform, consent to participate, sign HIPAA authorization for medical record collection, and provide ≥1 provider/care site for record retrieval will be included in the cohort. Specific aims: The cohort aims to generate contemporary real-world data relevant to understanding demographic and clinical characteristics, SDoH, diagnostic/testing pathways, treatment patterns, and clinical outcomes, including AEs and AE management. Specifically, demographic and SDoH differences in management, outcomes, and the patient experience during and following eBC diagnosis and treatment will be evaluated. The cohort design and the data collected will evolve as the eBC landscape evolves to continuously address new research questions around diagnosis, management, outcomes, and patient experience. Statistical methods: The demographics, SDoH, clinical characteristics, treatments, healthcare resource utilization, eBC outcomes, such as recurrence and progression, and patient experience will be summarized for the cohort overall and by pre-determined subgroups using descriptive statistics. Additional analyses include, but are not limited to, evaluating the impact of key exposures, such as SDoH, on treatment and diagnostic pathways, treatment compliance, clinical outcomes, and PROs. All analyses will be prespecified in study-specific statistical analysis plans. Present accrual and target accrual: At least 3,000 patients will be enrolled in the PicnicHealth eBC Cohort. As of July 2023, 843 patients have onboarded to the PicnicHealth platform and will be screened for eligibility into the eBC registry cohort. Contact information for people with a specific interest in the study: For additional information, please contact breastcancer@picnichealth.com. Citation Format: Haley Friedler, Meghan Tierney, Melinda Baker, Gillian Hanson, Josefa Briceno, Karen Smith, Michele Baber, Kara Glover, Xiaoqing Xu, Kellie Ryan, Zulikhat Segunmaru, Clara Lam, Maryam Lustberg, N. Lynn Henry, Rachel Greenup, Marianna Chavez, Joseph Unger, Alice Ho, Deborah Collyar. EVOLVE: An Ambispective, Patient-Centered, Real-World Early-Stage Breast Cancer Study in the United States [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-19-04.

Many women eligible for breast conservation therapy (BCT) elect unilateral mastectomy (UM) with or without contralateral prophylactic mastectomy (CPM) and cite a desire for “peace of mind.” This study aimed to characterize how peace of mind is defined and measured and how it relates to surgical choice. Nine databases were searched for relevant articles through 8 October 2023, and data were extracted from articles meeting the inclusion criteria. The inclusion criteria were met by 20 studies. Most were prospective cohort studies (65