PROJECT SUMMARY Lung cancer remains one of the most prevalent and deadly cancers in the US. Most lung cancers are not diagnosed until after the cancer has already metastasized; stage IV patients have 5-year survival rate of only 8.2%. While in the past stage IV patients with non-small cell lung cancer (NSCLC), the most common histology, were treated with chemotherapy, in recent years novel systemic therapies, such as targeted therapy and immunotherapy, have been introduced and have substantially changed the landscape of late stage lung cancer outcomes. Early-stage, surgical patients have been shown to benefit from adjuvant targeted therapy as well. Targeted therapies work by inhibiting specific molecular pathways, the most commonly targeted of which is the epidermal growth factor receptor (EGFR) tyrosine kinase pathway. The anaplastic lymphoma kinase (ALK), KRAS, and BRAF pathways are other targetable oncogenic pathways. These novel therapies require genetic testing as a basis for treatment to ensure that a druggable target is present, as not all tumors present themselves with target mutations. About 30% of NSCLC patients will be eligible. Immunotherapies, specifically drugs that inhibit the protein 1–programmed death ligand 1 (PD-1–PD-L1) pathway, can also substantially improve survival in a subset of NSCLC patients, but are usually prescribed to only those patients with a high PD-1 tumor mutational burden (TMB). Preliminary evidence suggests that utilization of novel target therapies and immunotherapy is disproportionately different according to race/ethnicity and socioeconomic status, which may partially explain the disparate survival outcomes in these groups of patients. More specifically, Black NSCLC patients may be less likely to receive molecular testing compared to White patients, making them less likely to access targeted treatments. However, no studies have yet to investigate the prevalence of oncogenic panel testing, meaningful for both targeted or immunotherapy treatment, in a population-based dataset such as SEER-Medicare, overall and according to race and access to quality care. To address this critical research gap, we propose the following aims: Aim 1a) Use SEER-Medicare claims data to investigate the prevalence of molecular tests among Black vs White advanced NSCLC patients. Aim 1b) Investigate how NSLC genetic testing varies by urban vs rural clinical practice. We hypothesize that molecular testing is significantly less likely to be performed among Black and rural NSCLC patients. This project will give important information on one of the main reasons for the high mortality observed in minority and minoritized NSCLC patients, while offering an opportunity for training in health disparities research, statistical analysis of large datasets, analysis and interpretation of genetic data. Thus the proposed aims of this supplement complement well the scope and mission of the original parent grant which is to expand capacity in genetics ...