How cancer grows and spreads - Growing a blood supply
All cells need a supply of oxygen and nutrients, and cancer cells are no exception. Without their own blood supply to nourish them, tumours cannot grow larger than the size of a grain of sugar.
As a tumour grows, it sends out signals to nearby blood vessels. These cause new blood vessels to sprout towards the tumour, effectively hijacking the blood supply. Scientists call this process angiogenesis.
This short animation shows how new blood vessels grow into a tumour, and how they provide a route for cancer cells to spread around the body.
Because they grow in a rapid and disorganised way, the blood vessels inside tumours are disorganised and 'leaky' - this is very different to those in healthy tissue. Scientists are trying to exploit these differences to develop treatments that specifically target the blood supply to cancers, and to deliver drugs more effectively into tumours.
Cancer Research UK scientists are at the cutting edge of angiogenesis research. They are investigating what triggers the process, the signals involved, and how we can apply this knowledge to tackle cancer.
Researchers have discovered that low levels of oxygen in a tumour - known as hypoxia - trigger the production of signals that 'hijack' blood vessels, causing new vessels to sprout towards it. Professor Adrian Harris at the University of Oxford is leading world-class research into this process, with the aim of developing ways to block it.
Our scientists, and researchers around the world, are developing and testing new anti-cancer drugs that shut off the blood supply to tumours. For example, we are funding a trial to test whether the new drug bevacizumab (Avastin), which affects the growth of new blood vessels, can improve survival for patients with stomach cancer.
At the University of Sheffield, Professor Gillian Tozer is studying the blood vessels and blood flow within tumours. Together with other researchers, she is investigating the potential of a drug called combretastatin to treat cancer, which works by shutting down the blood vessels within tumours.
But scientists have discovered that blocking angiogenesis is more tricky than first thought. At Barts & The London School of Medicine and Dentistry, Professor Kairbaan Hodivala-Dilke is studying angiogenesis-blocking drugs in great detail. She has found that some drugs may block the growth of tumour blood vessels at high doses but actually encourage their growth at low doses.
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