Signs and symptoms of cancer: the evidence

Cancer happens when the processes which control how a cell grows and divides don’t work properly. This means the cell is able to multiply out of control. These cells are damaged, and so don’t behave how a cell usually would. As the cancer develops, the cells can start spreading around the body.

If you can detect the cancer when it’s at an early stage, before it’s had the chance to get too big or spread to other parts of the body, it can often be easily removed or treated. If the cancer has spread, treatment becomes more difficult, and in almost all cases a person’s chances of surviving that cancer are much lower.

Malignant melanoma, the most serious type of skin cancer, is a good example of this. For melanoma, the most important factor affecting a person’s chances of surviving the disease is how thick the cancer is at the time it is diagnosed 1. If the melanoma is less than 1.5mm thick, 93 out of 100 men, and 97 out of 100 women, are alive at least five years after they were diagnosed. But if the melanoma is more than 3.5mm thick at the time it’s diagnosed, the number of people who survive five years is much less - just 47 out of 100 men, and 55 out of 100 women.²

So finding cancer early can make a real difference.

Sometimes people wonder what the point of seeing their doctor is, because they think of cancer as a death sentence.

But people do survive cancer. This is true even for those cancers that are associated with a poor survival rate overall.

Take lung cancer as an example. The percentage of people alive at least five years after diagnosis has not really changed since the 1970s, and stands at just 7%. ³ This figure is low because lung cancer is often diagnosed at an advanced stage when surgery, the treatment with the best chance of success, is not an option. But when lung cancer is diagnosed at its earliest stage, as many as 80% of people are alive five years after diagnosis. ⁴, ⁵ So diagnosing cancer at an early stage can make a real difference.

Our Symptoms of Cancer page lists some of the changes that may be signs of cancer. This is based in part on the European Code Against Cancer. All of the signs and symptoms on the list could be down to things other than cancer but, occasionally, they could be caused by cancer. Because treatment is more likely to be successful when cancer’s found early, it’s important that you see your doctor as soon as you can if you spot any of these changes.