CLO19-027: Assessment of Metastatic Invasive Lobular Carcinoma Management and Outcomes From 2004-2014: A Single Institution Experience

Abstract

Background: Invasive lobular carcinoma (ILC) accounts for 5%–15% of all invasive breast cancer cases. ILC has the propensity for distant late recurrence with widespread metastatic disease. To our knowledge, there is limited data on the clinical outcomes and treatment strategies of metastatic ILC. This retrospective study evaluates the overall survival (OS) and progression-free survival (PFS) in the metastatic ILC population at a single institution, focusing on first line treatment received in the metastatic setting. Methods: A retrospective chart review was performed on patients (Pts) diagnosed with metastatic ILC diagnosed at The Ohio State University Comprehensive Cancer Center between January 1, 2004 and December 31, 2014 using an IRB approved protocol. Patient demographics, clinical characteristics, and treatment modalities were summarized with descriptive statistics. OS (time from metastasis to death or last known follow-up) and PFS (time from diagnosis of metastasis to progression) were compared between types of first-line treatment: endocrine therapy (ET), chemotherapy (chemo), chemo followed by ET, ET plus CDK 4/6 inhibitor, or other treatments. OS and PFS estimates were generated using Kaplan Meier methods and compared using Log-rank tests. Results: 60 female pts were included in this study. The median age was 59 years (24–78). 45 (75%) pts were postmenopausal, 44 (73%) ER+/PR+, 14 (23%) ER+/PR-, and 2 (3%) ER-PR-, 28 (47%) with only bone metastases, 19 (32%) with visceral and bone metastases, and 13 (22%) with liver metastases. Twenty-eight (47%) pts received first line ET therapy, 12 (20%) received ET + CDK 4/6 inhibitor, 7 (12%) received chemo alone, 4 (7%) received chemo followed by ET, and 9 (15%) received other types of first line therapy. The median OS was 3.0 years, and the median PFS was 1.4 years. No difference in the Kaplan-Meier curves was found between first-line treatment groups in OS or PFS (OS: P=.247; PFS: P=.436). Discussion: ILC is a histologically distinct disease from invasive ductal cancer. It has been previously shown that invasive lobular cancer may not be as sensitive to adjuvant chemotherapy. We showed that in the metastatic setting there was no difference in PFS and OS among first line treatment groups. ET remains preferred treatment option; however, based on our data, chemotherapy can be considered in patient with metastatic ILC in the appropriate clinical context such as visceral crisis.