What Is Small Cell Lung Cancer (SCLC)? Key Facts

Small cell lung cancer (SCLC) makes up roughly 10-15% of lung cancer diagnoses and tends to grow and spread faster than non-small cell lung cancer, often being diagnosed after it has already spread.

SCLC is typically staged using a simpler two-category system — limited stage or extensive stage — rather than the four-stage system used for NSCLC, largely because SCLC has usually spread by the time it's found.

Because SCLC is aggressive and historically had fewer treatment breakthroughs than NSCLC, researchers have recently focused on identifying molecular subtypes within SCLC itself — often labeled SCLC-A, SCLC-N, SCLC-P, and SCLC-I — in hopes of eventually matching specific treatments to specific subtypes, similar to how biomarker testing already works in NSCLC.

Brain metastases are relatively common in SCLC, which is why several current trials specifically evaluate how new drugs perform against tumors that have spread to the brain, not just tumors in the lung.