Experts have dismissed claims that a herbal remedy can treat cancer.
Complementary and cancer specialists said it was "irresponsible" to suggest Carctol, a mixture of eight remedies, was linked to 'miraculous' recoveries.
The claims were made by Dr Rosie Daniel, the former head of the Bristol Cancer Centre, which promotes holistic treatment of the disease.
But she admitted she could not be certain it was the remedy which was responsible for patients' recoveries.
Carctol is based on traditional Hindu treatments. People taking it are also advised to adhere to a non-acidic diet and drink large quantities of water - up to five litres a day.
Carctol was devised by Dr Nandlal Tiwari from Rajasthan, who has been giving it to patients for 25 years.
I would urge cancer patients not to abandon conventional therapies, because that's the biggest mistake you can make
Professor Edzard Ernst, Peninsula Medical School
It is suggested it works by creating an alkaline environment in which acidic cancer cells cannot survive.
Dr Daniel, who prescribes Carctol before and after patients have had chemotherapy, said Dr Tiwari's theory was that it worked by helping the excretion of acids from the body.
She said it was a "detox" remedy, which pushed the kidneys, liver and bowel to excrete.
Dr Daniel told BBC News Online: "I'm simply reporting that I'm seeing an important phenomenon.
"I've been sitting on this for four years. eventually, my patients told me other people with cancer should be told about this."
She said she had seen people recover from cancer who were taking the remedy, including a woman who was told she had inoperable pancreatic cancer. whose tumour had gone after two years on the treatment.
"Over the years, I have seen a number of very remarkable recoveries, but since putting people on Carctol I have seen miracles.
"I have seen astounding results and they are mounting up.
"For the first time in 20 years, I have a medicine that I believe will make a difference."
She added: "I know some people are saying I am irresponsible, but my mission has been to help get information to people."
But asked how she knew it was Carctol which was having the beneficial effect on patients, and not something else they were taking, she said: "Well I don't."
Dr Daniel said she had seen no evidence of side effects, or drug interactions, but said they couldn't be ruled out unless there was "controlled scientific assessment".
Dr Richard Sullivan, head of clinical research at Cancer Research UK, told BBC News Online: "There are lots of claims made for lots of different products, when there isn't any evidence.
"We are dealing with vulnerable cancer patients, who will want to take something that could improve their chances.
Potential side effects
Edzard Ernst, professor of complementary medicine at the Peninsula Medical School in Exeter, told BBC News Online he fully supported the use of complementary therapies - once they had been proven to work.
He called the claims made for Carctol "irresponsible".
"The website does talk about clinical studies to support the remedy's effectiveness, but it is a commercial site, and the data is unpublished."
Professor Ernst said there had been natural treatments which had been effective against cancer, such as yew tree - which formed the basis for the drug Taxol, and periwinkle, which was the basis for Vincristine.
He added that if Carctol was shown to be effective, it too would be adopted by oncologists.
"It would be ridiculous for it to be disregarded by mainstream medicine if there was any evidence at all that it worked."
Professor Ernst added: "I would urge cancer patients not to abandon conventional therapies, because that's the biggest mistake you can make.
"And if you do take complementary therapies alongside conventional ones, do discuss it with your healthcare team."
He warned that one of the known ingredients in Carctol, rhubarb, had been linked with side effects including bone loss and muscle weakness, and could also interact with many conventional medications.