There are so many rare cancers it’s hard to answer this question. Examples of rare cancers are:
Carcinoid cancer – cancer of the neuroendocrine system – the cell communication system. It is cancer that results from glands that secrete hormones, but the tumours don’t grow there, they grow where the hormone was supposed to be going – usually around the gut. There are NO SYMPTOMS for this types of cancer. The tumours are tiny and numerous.
Primary CNS-lymphoma – which is a type of brain tumour. Lymphoma is cancer of the lymph cells which are responsible for your immune system. But the cancerous lymph cells end up in the central nervous system and typically tumours develop in the cerebral cortex of the persons brain.
Sarcoma – a cancer which originates within the embryo and then can become cancer of many tissuse within the body – bones, muscles, fat, cartillage.
Finally urinary bladder cancer is extremely rare. One of my friends Dads has it and he had to get his entire bladder removed.