Abstract A025: Enrollment of older adults in small cell lung cancer (SCLC) clinical trials compared with population-based U.S. incidence estimates
Authors: Yang Felice , Akinboro Oladimeji , Lerro Catherine , Rizvi Fatima , Mishra-Kalyani Pallavi , Kluetz Paul G. , Singh Harpreet , Rivera Donna R. 
Published: January 2023

Background: Small cell lung cancer (SCLC) is an aggressive form of cancer characterized by rapid progression, early metastases, and poor prognosis. Clinical trials (CTs) leading to approval of various classes of medical products have recently increased the treatment options available for SCLC patients. Older adults ≥65 years of age are historically under-enrolled in CTs. The U.S. population continues to age. There is often limited evidence supporting safety and effectiveness of treatment among this population because of disproportionate enrollment of older adults in CTs. To characterize patterns of SCLC CT enrollment by age, selected SCLC CTs (immunotherapy and cytotoxic agents) were compared to U.S. SCLC incidence data. Methods: We identified six CTs for treatment of SCLC to support marketing applications submitted to the FDA between 2018-2019. Descriptive statistics based on the pooled CT data were calculated and compared with incident U.S. SCLC cases diagnosed between the same period, using data from the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) Program. While SEER is a U.S. population-based representative sample, data from the trials included patients outside the U.S. that were submitted to support marketing applications with applicability to U.S. clinical practice. Results: A total of 1,642 patients were enrolled in the six included SCLC CTs. In this sample, 42.9% were age ≥65 years, compared to 66.6% of incident U.S. SCLC cases. This disparity persists with increasing age: 8.5% of CT enrollees were age ≥75 years and 1.8% of CT enrollees were age ≥85 years, compared to 27.5% and 4.5% of incident U.S. SCLC cases, respectively. Discussion: Based on these findings, older adults are underrepresented in SCLC CTs, while representing a substantially larger proportion of incident U.S. cases. The number of SCLC patients over 65 years is likely to increase the U.S. population continues to age. Aging presents specific challenges with respect to cancer care due to increased presence of comorbidities and the potential for variance in patient and provider treatment preferences, which might partially explain the results. These results demonstrate an opportunity to evaluate and fix barriers to trial entry for older adults to ensure representative evidence generation that is reflective of the epidemiology of the disease and the real-world population.

Citation Format: Felice Yang, Oladimeji Akinboro, Catherine Lerro, Fatima Rizvi, Pallavi Mishra-Kalyani, Paul G. Kluetz, Harpreet Singh, Donna R. Rivera. Enrollment of older adults in small cell lung cancer (SCLC) clinical trials compared with population-based U.S. incidence estimates [abstract]. In: Proceedings of the AACR Special Conference: Aging and Cancer; 2022 Nov 17-20; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_1):Abstract nr A025.