Cancer is generally defined as a malignant tumour that tends to infiltrate surrounding tissues and organs and can metastasise to distant sites with a poor prognosis. Carcinoid tumours are just a specific pathological type of cancer, intermediate between benign and malignant tumours, slow growing, less likely to metastasise, less malignant, often occurring in the gastrointestinal tract and respiratory tract, and can generally be cured with aggressive surgical excision and have a better prognosis.