The Brio Clinic offers treatments such as hyperthermia (heat therapy), HIFU (high intensity focused ultrasound), pH transformation therapy, immunotherapy and "infusions of micellized nutrients".
Researcher Dr Shaun Holt, author of Natural Remedies that Really Work: A New Zealand Guide, which assesses alternative and complementary cancer therapies, says there is no such thing as a magic bullet.
"I totally understand [cancer patients] wanting to explore every avenue and to maximise chances of survival. Unfortunately, these magic bullets and these amazing clinics just don't exist.
"I would advise that people do not go to an overseas alternative cancer treatment centre. The chances of success are absolutely miniscule and there will almost always be a very high charge associated. While it is the patient's right to go if they want to, I would strongly advise against it."
Holt said that if such treatments worked, they would be available from doctors in New Zealand.
Holt said as the population aged and the number of cancer diagnoses increased he was seeing more and more people looking to countries like Thailand and Mexico for expensive alternative therapies.
The chances of success are miniscule.
Cancer society medical director and oncologist Dr Christopher Jackson said he was concerned at some of the promises offered to people.
"There are a large number of non-evidence based therapies out there, which people get very rich off, which is clearly exploitative," he said.
"I understand at a personal level why someone who's 26 would want any chance at anything that may work, but I think that does leave people potentially vulnerable to exploitation by unscrupulous practitioners."
He said the Cancer Society strongly supported evidence-based therapies and patients should talk with their New Zealand-based oncologist before sinking large amounts of money into therapies that were potentially spurious and harmful.
Ferreria was farewelled last month by hundreds of friends and family in Auckland.
The Air New Zealand hostess died aged 45, a year-and-a-half after she was diagnosed with cancer. After returning to New Zealand in early May she went into hospice care.
Like Ferreira, the young woman who died this week saw the Brio clinic as her last chance.
She had battled melanoma since 2003, exhausting every drug, trial and treatment available in New Zealand.
The clinic told her about a fortnight ago it could help her with a course of treatments over 35 days at a cost of $130,000, but she needed to get to Bangkok next week.
The Brio Clinic has not responded to the Herald on Sunday's questions.
