The US government has approved a drug that halts the growth of tumours by cutting off their blood supply.
The drug works by starving the tumour of oxygen and nutrients
Avastin has been shown to prolong the lives of those with advanced bowel cancer.
It works by starving cancerous tumours of blood, thus preventing them from growing in the body.
Unlike chemotherapy, which works by killing all dividing cells, this new drug only targets cancer cells.
The backing of the new treatment is being seen as a potentially very significant breakthrough in the fight against cancer.
The drug has been shown to prevent the formation of new blood vessels, thereby denying tumours the oxygen and other nutrients needed for their growth.
In approving it, the US Food and Drug Administration described it as the first drug that had been proven to delay tumour growth.
The FDA had "fast tracked" approval for the drug because studies had produced such positive results.
So far, Avastin is being used in combination with chemotherapy to treat patients with advanced colon cancer.
In the US study, Avastin was given to 900 patients with advanced bowel cancer.
They were either given Avastin along with standard chemotherapy, or chemotherapy alone.
The patients given the combined treatment saw an increase in survival of an average five months - a significant benefit for patients with this kind of cancer.
A Food and Drug Administration official who oversaw the Avastin review said the survival advantage of the drug was unusual.
Dr Patricia Keegan said: "In every subset analysis of the trial, every patient regardless of gender, age, extent of disease - all of them responded."
Genentech, the company that created the drug, says it is now looking at how Avastin might be used to treat other common cancers, such as breast cancer and lung cancer.
A spokesman for Cancer Research UK said: "Avastin is the first drug targeting angiogenesis to be licensed in the US.
"It has shown significant success in halting tumour growth in a variety of patients, and holds considerable promise in fighting colorectal cancer."