Doctors say Katie's cancer is treatable but she's 'healing it' with veganism instead.

Katie Britton-Jordan has breast cancer. Diagnosed last year as Stage 2, it’s life-threatening. But with a combination of a mastectomy, chemotherapy and radiotherapy, doctors told the British mum that they are optimistic they can treat the deadly disease.

Still, she said no.

Shunning evidence-based treatment, the 38-year-old from Derbyshire in the UK is opting instead to use a dangerous and unproven combination of alternative therapies and a vegan, gluten-free, sugar-free diet to fight her cancer.

“I have always been into alternative health. I started researching and decided there was no way I was having chemotherapy and radiotherapy. Initially I wasn’t sure about the surgery,” she told The Mirror.

“I didn’t know if it was a good thing or a bad thing but the more I read into it, the more I decided I didn’t want to do it either.”

Britton-Jordan's cancer was discovered last year after she noticed a lump in her breast while breast-feeding her now three-year-old daughter. Doctors found three tumours and diagnosed her with Stage IIa triple negative breast cancer.

Despite the growth of a fourth tumour in the months since, Britton-Jordan persists with her regimen of supplements, sessions in a hyperbaric oxygen chamber and told The Mirror she is "looking into mistletoe therapy, where extracts of the plant are injected into the body."

While her family support her, the science doesn't.

In its position statement on alternative and complimentary therapies (that is, those used in addition to conventional medicine), Cancer Council Australia warns that such an approach is unproven and can harm the patient's prospect of remission or cure.

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"Health claims for many complementary and alternative therapies are far in excess of the available scientific data. Similarly, information on adverse effects and interactions with conventional medicines is often lacking," the organisation says.

"The quality and safety of some complementary and alternative medicines cannot be guaranteed, as these preparations are not subjected to the evaluation process that conventional pharmaceuticals undergo."

As integrative medicine specialist Professor Kerryn Phelps previously told Mamamia, a holistic approach to treatment can be beneficial to the patient, but it's problematic that many cancer sufferers are obtaining information about treatments without professional guidance.

“The main pitfalls are that people are making it up as they go along. People have access to the internet and a whole range of different types of information sources, not all of which are credible or accurate," she said.