Cancer cells within a single tumor are not the same

Different cancer cells in the same tumor may have different mutations. Although an initial series of mutations lead to the appearance of cancer, new mutations emerge over time and cause changes in the cells.

This means that the treatment (why cancer is so hard to cure) may kill all one type of cell in the tumor, while other resistant cells survive after treatment and increase in number again. If not caught early enough, cancer can also spread to other parts of the body - a new mutation gives cancer cells the ability to survive in the blood and metastasize elsewhere.

Treatment may eventually stop

Genetic mutations that cancer cells acquire over time mean that the cells change the way they behave. During treatment, this can be a very difficult problem because mutations can cause cancer cells to become resistant to treatment over time - patients may successfully receive treatment for a period of time and then find that it stops working.

If this happens, the patient will have to be treated differently - but again, the cancer may become resistant to the new drugs. If treatment fails, there may be no other option. That's why we fund researchers like Dr. Maite Hualte in Spain, who is trying to figure out how to overcome this resistance in cancer.