69 The Importance of Tri-Modality Therapy for De Novo Stage IV Invasive Lobular Carcinoma (ILC) Presenting With Bone-Only Metastases

Publication
Article
Miami Breast Cancer Conference® Abstracts Supplement41st Annual Miami Breast Cancer Conference® - Abstracts
Volume 38
Issue 4
Pages: 63-64

Systemic Therapy Only vs Locoregional Therapy With Systemic Therapy in Patients With Stage IV ILC With Bone-Only Metastases

Systemic Therapy Only vs Locoregional Therapy With Systemic Therapy in Patients With Stage IV ILC With Bone-Only Metastases

Background

Locoregional therapy (LRT) of the primary breast carcinoma (BC) in the setting of de novo oligometastatic stage IV disease is strongly debated, despite both retrospective data and prospective trials supporting it. This study aims to determine the overall survival (OS) benefit of LRT combined with systemic therapy (ST) vs ST only in the management of invasive lobular carcinoma (ILC) presenting with de novo stage IV bone-only metastases.

Methods

Patients who presented from 2014 to 2022 with bone-only metastases were retrospectively identified from a prospectively maintained multi-institutional cohort of patients with oligometastases. Univariable and multivariable Cox proportional hazards models were used to identify factors associated with OS. The Kaplan-Meier method was used to estimate time-to-event outcomes. Groups were compared using the log-rank test. Variables included demographics, tumor size, histology, receptor status, use of endocrine therapy, chemotherapy, bisphosphonates, and ovarian suppression.

Results

Of 744 patients identified, 83 (11%) had ILC. Patients with ILC were older (58.9 years vs 52.6 years; P < .05), had a higher number of multiple tumors (81% vs 61%; P < .05), and had lower HER2-positive frequency (12% vs 29%; P < .05) than those with IDC. Hazard of death was 63% higher in ILC vs IDC (HR, 1.63; 95% CI, 1.1-2.24; P = .003). Median OS was 69 months and 49 months in IDC and ILC, respectively. For patients with ILC, baseline characteristics of age, body mass index, T stage, hormone receptor status, ST, and intervention to metastatic sites did not differ between those who had LRT plus ST (n = 25; 30%) vs ST only (P > .05). At a median follow-up of 36 months (IQR, 26-57), 48% (n = 40) of patients with ILC had died. In the ILC group, Kaplan-Meier OS estimates demonstrated longer OS among patients who underwent LRT+ST (median 78 months) vs 38 months with ST only, log-rank P = .008; Figure). Hazard of death was 63% lower with LRT+ST vs ST only (HR, 0.37; 95% CI, 0.18-0.79; P = .01). LRT plus ST was the only factor contributing to OS at 36 months (OR, 3.64; 95% CI, 1.33-11.20; P = .02).

Conclusion

Patients with ILC and de novo bone-only metastases have a worse prognosis compared to those with IDC, but those who have LRT plus ST have a better OS than those who receive ST only. While there may be selection biases in our multi-institutional retrospective cohort, patients with ILC should be considered for LRT for the primary tumor combined with ST.

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44 Variant of Uncertain Significance (VUS) Genetic Testing Results and Mastectomy Choice in Lumpectomy-Eligible Patients
45 Application of the 7-Gene Biosignature in Palpable Versus Nonpalpable Ductal Carcinoma In Situ in a Black Patient Population: Does Palpability Suggest a More Aggressive Genomic Risk?
45 Application of the 7-Gene Biosignature in Palpable Versus Nonpalpable Ductal Carcinoma In Situ in a Black Patient Population: Does Palpability Suggest a More Aggressive Genomic Risk?
46 Comparative Analysis of Breast Conserving Therapy vs Mastectomy in Multifocal and Multicentric Breast Cancer: A Review of the Literature
46 Comparative Analysis of Breast Conserving Therapy vs Mastectomy in Multifocal and Multicentric Breast Cancer: A Review of the Literature
47 Can We Identify Factors That Predict DCIS Upgrade to Invasive Cancer at Mastectomy?
47 Can We Identify Factors That Predict DCIS Upgrade to Invasive Cancer at Mastectomy?
48 The Era ‘or Error’ of Second Localization Procedures
48 The Era ‘or Error’ of Second Localization Procedures
49 The Influence of Race on Complications in Breast Conservation Surgery: A Single Institution Study
49 The Influence of Race on Complications in Breast Conservation Surgery: A Single Institution Study
51 Ductal Carcinoma In Situ With Microinvasion on Biopsy—What Are the Predictors of Upstaging?
51 Ductal Carcinoma In Situ With Microinvasion on Biopsy—What Are the Predictors of Upstaging?
52 UK Experience of Non-Radioisotope, Non-Magnetic Guided Breast Wide Local Excision and Sentinel Node Biopsy
52 UK Experience of Non-Radioisotope, Non-Magnetic Guided Breast Wide Local Excision and Sentinel Node Biopsy
53 The Utility of Sentinel Lymph Node Biopsy in High-Grade Ductal Carcinoma In Situ
53 The Utility of Sentinel Lymph Node Biopsy in High-Grade Ductal Carcinoma In Situ
54 The Evaluation of Expression Levels of CXCR4, CXCL12, and LASP1 Genes in Peripheral Blood Samples of Breast Cancer Patients
54 The Evaluation of Expression Levels of CXCR4, CXCL12, and LASP1 Genes in Peripheral Blood Samples of Breast Cancer Patients
55 Language as a Barrier to Deep Inspiration Breath Hold (DIBH) Radiation Therapy for Left  Breast Cancer
55 Language as a Barrier to Deep Inspiration Breath Hold (DIBH) Radiation Therapy for Left Breast Cancer
56 Predictive Factors Correlating With Pathologic Complete Response Rates in Racially Diverse, Minority Populations Receiving Neoadjuvant Therapy for HR+/HER2– Breast Cancer
56 Predictive Factors Correlating With Pathologic Complete Response Rates in Racially Diverse, Minority Populations Receiving Neoadjuvant Therapy for HR+/HER2– Breast Cancer
57 Addressing Barriers to Identifying Patients With HER2-Low Metastatic Breast Cancer in a Large Community Oncology Practice
57 Addressing Barriers to Identifying Patients With HER2-Low Metastatic Breast Cancer in a Large Community Oncology Practice
58 Prospective Longitudinal Assessment of Financial Toxicity Among Breast Cancer Patients
58 Prospective Longitudinal Assessment of Financial Toxicity Among Breast Cancer Patients
59 Acceptability of Microbiome Sampling-Based Surgical Oncology Research in Minority Breast Cancer Patients
59 Acceptability of Microbiome Sampling-Based Surgical Oncology Research in Minority Breast Cancer Patients
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