Cancer is uncontrolled cell growth.
Different cell types in your body can become cancerous, which makes something them different.
Pancreatic cancer is one of those, you are dead in three months, as is renal cell carcinoma if it metastisizes up the vena cava.
When a cancer metastisizes, it means it has spread to other areas of the body, some are quite common, like prostatic to bone, breast to bone, colon to liver.
Sometimes the cancer may show up in the secondary organ, for example liver cancer, but really it is colon cancer.
There are some cancers you can have for twenty years, for example multiple myeloma, which is one of your white blood cells (b-cells), or carcinoid tumours, which are the endocrine tissue that lines your gut and respiratory tract.