A study presented today by Dr. Nobuyuki Takahashi of the Center for Cancer Research (CCR), National Cancer Institute (NCI), Bethesda, Md. at the IASLC World Conference on Lung Cancer Singapore demonstrates that small cell lung cancer (SCLC) may have an inherited predisposition and lays the foundation for understanding the interaction between genotype and tobacco exposure in exacerbating SCLC risk as well as potential therapeutic implications. Because tobacco is the dominant carcinogen, secondary causes of lung cancer are often diminished in perceived importance, especially in SCLC, the most lethal lung cancer. SCLC is almost exclusively related to tobacco and comprises 15% to 20% of all lung cancers.