PS5-06-11: Exploring Characteristics and Outcomes of Metachronous Primary Breast and Lung Cancer in A Diverse Cohort

Abstract Introduction: Despite breast and lung cancer being the most common malignancies in females, the occurrence of double primary cancers has been rarely reported in literature. It is well-established that at an earlier age of diagnosis in patients with breast cancer is linked to more aggressive phenotypes, highlighting the importance of early screening in this demographic group. There is a deficiency in the literature related to secondary thoracic malignancies among this high-risk group. Methods: This retrospective case series reviewed a cohort of eight patients with double metachronous, primary breast and lung cancers at the Sylvester Cancer Center. Data on patient demographics, diagnoses, treatment modalities, and outcomes were obtained from electronic health records. Results: All 8 patients were biologically female with a median age of 58.5 years. Racial distribution was 25% Asian, 12.5% Black and 62.5% White. 80% of White identified as the Hispanic/Latinx ethnicity. 62.5% of patients were never-smokers and 12.5 % were light, former smokers. The median age of diagnosis of breast and lung cancer was 60 years and 62.5 years, respectively. The average time between both diagnoses was 1.9 years (range 0.33 - 4 years). The majority (87.5%) of genetic profiles indicated a hormone receptor-positive mutation, with 33% of this genetic subset also showing an EGFR mutation. 75% of lung tumors were PDL-1 negative. Our review also indicates a decrease in concern for smoking. Despite no statistical significance between ethnicity and age of diagnosis of breast or lung cancer (p= .157), there was a trend demonstrating Hispanic/Latinx patients being diagnosed at an earlier age for both. There was no statistical significance between ethnicity and smoking status (p= .465), or ethnicity and time between diagnoses (p = 1). Conclusions: In this diverse, real-world cohort of patients with metachronous and synchronous lung and breast cancers, we noted interesting, hypothesis-generating observations. Trends indicated an earlier diagnosis of both breast and lung cancer in Hispanic/Latinx patients. 75% of our cohort had a dual diagnosis of breast ductal carcinoma and lung adenocarcinoma. 87.5% of individuals in our cohort displayed a hormone receptor-positive profile and 75% a PDL-1 negative prevalence. This case series confirms the importance of screening breast cancer patients with low-dose CT for early detection of lung cancer. Since double primary breast and lung cancer is rare, molecular profiling with next-generation sequencing could also provide insightful information. Citation Format: K. Sureshkumar, R. Dawar, S. Kareff. Exploring Characteristics and Outcomes of Metachronous Primary Breast and Lung Cancer in A Diverse Cohort [abstract]. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS5-06-11.