When * Localized: the cancer is confined to the lung (aka: limited stage SCLC). * Regional: the cancer has spread to lymph nodes (or glands) within the chest (between limited and extensive stage SCLC). Lymph nodes act as a filtering system outside the lung, collecting cancer cells that are beginning to migrate out of the lung. * Distant: the cancer has spread (or metastasized) to other parts of the body (aka: extensive stage SCLC). At the time of diagnosis, 60–70% of people already have metastases.<unk>  is an undifferentiated neoplasm composed of primitive-appearing cells. As the name implies, the cells in<unk> s are<unk> er than normal cells, and barely have room for any cytoplasm. Some researchers identify this as a failure in the mechanism that controls the size of the cells.
Small-cell carcinoma
Adenomatoid tumor
Mucinous carcinoma
Sarcomatoid carcinoma
Spindle cell carcinoma
Signet ring cell carcinoma
Adenosarcoma
Adenocarcinoma