Chinese herb cancer warning

A plant from the Aristolochia family

A toxic chinese herb now off the market in the UK may have left a legacy of cancer amongst those who took it.

The herb Aristolochia - sometimes used in remedies for fluid retention, eczema and rheumatic symptoms - has been linked with a much higher risk of kidney and urinary cancers.

It could be many years before the consequences of cancer caused by Chinese herbs can be quantified

Dr Graham Lord

Previously it had been associated with kidney failure in some cases, but the cancer came as a surprise to doctors.

The Medicines Control Agency (MCA), which is responsible for the safety of medicines and remedies prescribed or sold, has already made Aristolochia a prescription-only medicine.

It has not been officially included in Chinese remedies sold in the UK for some years.

But the government moved to ban the importation of a number of other Chinese remedies, which in theory contain different herbs, after quality checks revealed contamination with Aristolochia in some brands.

But the research, published in the New England Journal of Medicine, is still likely to worry some patients who have taken the medicine in the past.

The problem came to light when Belgian doctors examined patients who had suffered the known side-effect of kidney failure after taking Aristolochia.

Most had inadvertantly consumed the herb after it was mistakenly added to a slimming preparation - 80 cases of kidney failure were caused by this.

The doctors found patients whose kidney had failed also had a 46 times greater risk of cancer, mainly carcinoma of the ureter, the tube linking the kidneys to the bladder through which urine passes.

Malignant growths

Usually, people have a 1% risk of developing the disease.

The key ingredient of Aristolochia is aristolochic acid, which is carcinogenic. Traces of this were found in many of the patients with tumours.

Aristolochic acid is thought to damage the body's DNA, increasing the risk of malignant growths.

While in the UK, not as many cases of kidney failure caused by Aristolochia have been reported, there are still concerns that people who have taken remedies containing it in the past could be at risk.

Dr Joelle Nortier, who led the Belgian study, encouraged anyone who had taken a preparation containing the herb to get themselves tested for urinary tract cancer.

A UK expert, Dr Graham Lord, from the Hammersmith Hospital in London, described the findings as "very disturbing".

He said: "It could be many years before the consequences of cancer caused by Chinese herbs can be quantified, but quite clearly the risk of developing cancer is very high."