Cancer is a disease of the cells in the body. There are many different types of cells in the body, and many different types of cancer which arise from different types of cells.

Authored by , Reviewed by Dr Hayley Willacy | Last edited | Meets Patient’s editorial guidelines

Cancer occurs when cells become abnormal and multiply out of control. Different cells in the different parts of the body when multiplied cause different cancers.

Some grow and spread more quickly than others and some are easier to treat than others, particularly if diagnosed at an early stage.

Treatments can vary - some respond to chemotherapy, radiotherapy, or other treatments, while some may need surgery.

Some cancers have a better outlook (prognosis) than others - having a very good chance of being cured. For some types of cancer, the outlook is much poorer and therefore these have to be managed in a different way.

So, each cancer is different and behaves differently. We cannot put 'cancer' into one box. In each case it is important to know exactly what type of cancer has developed, how large it has become, whether it has spread and how well the particular type of cancer responds to various treatments. This will enable you to get reliable information on treatment options and outlook.

Causes of Cancer

Further reading and references

Health Tools

Feeling unwell?

Assess your symptoms online with our free symptom checker.

Start symptom checker

Get Support

On the forums


Share your experience with 1622 members from our Cancer community.

Join the discussion

i think i have a brain tumor. i could write a book but ill keep it short because i dont know if many people seem to respond. I also posted on the eye forum with no replies. -last hear had head pressure and vision issues so was sent for mri. It was clean. Have an optic nerve issue and the …