In this video, Evan W. Alley, MD, PhD examines recent advances in our understanding of non-small cell (NSC) lung cancer and new developments in the diagnosis and systemic treatment of the disease. Once considered a single entity, NSC is now thought of as a heterogeneous disease that varies across the patient population in histology, and molecular and genetic characteristics. This expanded understanding, Dr. Evans explains, has permitted molecular profiling and targeted therapies for NSC lung cancer, and lately, the development of treatments for specific resistance mutations as they arise in the course of therapy.