Small cell lung cancer (SCLC) is a type of highly malignant lung cancer that is composed of small ovoid cells. In the past, SCLC was called oat cell carcinoma because the microscopic appearance of the cells was felt to resemble oats. SLCLC usually originates near the bronchi and in many cases may grow and metastasize quickly.

POT1 tumor predisposition (POT1-TPD) is characterized by an increased lifetime risk for multiple cutaneous melanomas, chronic lymphocytic leukemia (CLL), angiosarcoma (particularly cardiac angiosarcomas), and gliomas. Additional cancers (e.g., colorectal cancer, thyroid cancer, breast angiosarcomas) have been reported in individuals with POT1-TPD but with very limited evidence. The age of onset for first primary cutaneous melanoma ranges from 15 to 80 years. The majority of POT1 associated cancers are diagnosed in adulthood.