Subtype-specific trends in lung cancer incidence and survival: A SEER analysis (2004–2021).

Abstract

1643 Background: Lung cancer remains a leading cause of cancer mortality, with adenocarcinoma, squamous cell carcinoma (SCC), and small cell lung cancer (SCLC) as key subtypes. Advances in early detection (e.g., low-dose CT screening post-2013) and systemic therapies (e.g., targeted agents and immunotherapies [IO], approved 2015 for adenocarcinoma/SCC, 2018 for SCLC) have transformed care. However, links between incidence trends and survival outcomes remain unclear.This study leverages SEER data (2010–2021) to extend prior analyses (Howlader et al. 2000-2017, NEJM 2020) and evaluate subtype-specific trends, focusing on the post-2015 era of IO adoption and updated screening eligibility. Methods: Age-adjusted incidence and 3-year relative survival rates for adenocarcinoma, SCC, and SCLC were analyzed using SEER data (2004–2021), stratified by stage. Joinpoint regression identified significant trend changes. Survival shifts >2% annually were temporally linked to key milestones: low-dose CT screening (2013), EGFR/ALK inhibitors (2013), and IO (2015). Results: For adenocarcinoma, distant-stage survival rose from 12.8% (2011) to 23.0% (2018), with a sharp +3.1% annual increase in 2018 aligning with immunotherapy adoption. Localized and regional survival improved by 5.3% and 6.5%, respectively, over the study period. These trends probably reflect the combined impact of early detection and systemic therapies. In SCC, localized-stage survival increased from ~56% to ~66% after 2015, driven by earlier detection and reduced late-stage incidence. However, regional and distant-stage survival saw only modest gains (~7%), highlighting limited advancements for advanced disease. SCLC showed the least survival improvements despite declining incidence, largely attributed to reduced smoking. Distant-stage survival stagnated at ~4–6%, while localized-stage survival improved transiently by 17% from 2010 to 2012, likely reflecting temporary improvements in early-stage management. However, overall outcomes for SCLC remain poor, underscoring an urgent need for new therapies. Conclusions: Advancements in lung cancer treatment and cancer screening have led to significant survival gains. Adenocarcinoma’s distant-stage survival improvements highlight the transformative impact of immunotherapy, while localized SCC gains emphasize the role of early detection and screening. SCLC remains a major challenge, with survival rates stagnating despite a steady decline in incidence. Further innovation in SCLC therapies, along with equitable access to both screening and novel treatments, is crucial to improving outcomes across all lung cancer subtypes. Survival data beyond 2018 for metastatic disease and post-2024 for localized disease (following IO approvals for respective indications) will provide deeper insights into the real-world impact of these therapeutic advancements.