Patients have been advised to carry on taking an anti-cholesterol treatment despite research that suggested it may be linked to higher cancer rates.

Inegy, a therapy that combines simvastatin with another drug called ezetimibe, was linked to slightly raised levels of a variety of cancers in an international study whose results were published in the New England Journal of Medicine.

Scientists reported that of the 1,873 patients involved in the study, 93 developed cancers including skin and prostate tumours, compared to 65 who took a placebo.

The Oslo-based researchers admitted however that the result was small and could have occurred by chance.

The Simvistatin and Ezetimibe in Aortic Stenosis (SEAS) study also cast doubt on Inegy's effectiveness in reducing the rate of progression of aortic disease in patients with a partially blocked heart valve, a condition that has no other proven treatment except surgery.

Two larger scale studies of the combination therapy, which will involve nearly 30,000 patients and are still ongoing, have not confirmed the cancer link, according to analysis at Oxford University. During these studies, 313 patients taking the drugs have so far developed cancer compared to 326 taking a placebo.

Tens of thousands of patients have taken Inegy in Britain, where around 300,000 prescriptions for the combination therapy have been issued over the last two years.

Dr Mike Knapton, the director of prevention and cure at the British Heart Foundation, said that patients should not make any sudden changes to their drug regime.

“If you have been prescribed ezetimibe you should continue to take it," said Dr Knapton.

"If you have concerns about side-effects of this or other medication, you should talk to your doctor to weigh up the risks and benefits.”

Dr Knapton added that it was important to find out more information about the long term effects of Inegy, a relatively new treatment, before jumping to conclusions.

“At the moment it’s not clear if there is a risk. It would be a disaster if, on one hand, a drug which benefits patients gets shelved," he said.

“On the other hand, we don’t want to give large numbers of patients a drug which has got an increased risk of cancer associated with it.

“The data from the big trials are encouraging but the evidence is not yet conclusive, because many of the patients studied have been followed up for a relatively short period of time so far.

“Because one study did show a cancer risk, it is crucial that others continue and are monitored closely to definitively confirm or refute any link.

“People should be reassured that drug regulators will act quickly if robust evidence of risk to patient health appears."

The National Institute for Health and Clinical Excellence (Nice), the NHS drug watchdog, approved the wider use of Ezetimibe in November for the treatment of high levels of cholesterol in the blood.

In the US, the Food and Drug Administration has launched an investigation into the drug.

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