Statins could cut the risk of dying from cancer by up to half, large-scale research suggests. A series of studies of almost 150,000 people found that those taking the cheap cholesterol-lowering drugs were far more likely to survive the disease.
Experts at the world's biggest cancer conference in Chicago said they were "very excited" by the findings.
Research found that for some of the most common cancers, including breast, bowel, prostate and ovarian disease, death rates were at least 40 per cent lower among those taking statins. For some rarer cancers, the difference was up to 55 per cent.
Across the board, cancer mortality was a fifth lower for those on the pills. One study suggested they were "more effective than chemotherapy," experts said.
Cancer specialists said the findings were extremely encouraging, giving "an added push" to the case for millions more to take the drugs.
The studies did not show statins would prevent cancer. But they suggest taking them daily could save thousands of lives, by slowing the spread of diseases.
Doctors said it was not clear why they had such an effect, but the drugs reduce cholesterol, which is known to help the spread of disease.
Heart disease experts credit statins with saving around 7,000 lives a year in the UK, by warding off heart attacks and strokes. The new research, presented at the American Society for Clinical Oncology's annual meeting, suggests they could do far more, saving the lives of thousands more people with cancer.
The 15-year study involved 146,000 American women, aged 50 to 79. Some of the most significant differences were in the most common cancers. A fall in mortality of 43 per cent was seen for bowel cancer - the fourth most common, with 40,000 diagnoses in the UK each year.
For breast cancer, the most common cancer in women, with 50,000 cases annually, mortality was 40 per cent lower. The biggest difference was in bone cancer, where rates dropped by 55 per cent.
Dr Ange Wang of Stanford University's school of medicine, who led the study, said the findings suggested a simple daily pill could become a significant weapon in the war on cancer. The findings came from the Women's Health Initiative Observational Study, but there was no reason to think they would not apply equally to men, researchers said.
A second study, by the Rutgers Cancer Institute of New Jersey, examined death rates among 20,000 men with prostate cancer. Those taking statins were 40 per cent less likely to die from the disease, which is the most common cancer in men, with 40,000 diagnoses each year.
Deaths from all causes fell by one quarter among those taking statins.
Lead researcher Dr Grace Lu-Yao said: "Prostate cancer has modern therapies which cost in the US$100,000 range for a few months of therapy and the effect is about the same."
She said a major clinical trial would be needed "before you go to the clinic and say everybody gets statins".