She embarked on an extraordinary odyssey that cost her more than $100,000 (pounds 63,500) in the four years before her death.
Her search for a cure took her to clinics in Mexico, Los Angeles and the Dominican Republic. She tried the Gerson diet, a challenging regime requiring rigorous self-control, in a clinic that charged $500 (pounds 317) a day. At a second clinic, she drank wheatgrass juice until it made her retch.
In January this year, when she was clearly dying, she went to the Institute of Magnetic Therapy in Santa Domingo which charges thousands of dollars for a treatment devised in Russia to destroy the cancer cells with magnetic waves. Her mother, Mirella, said: "If we hadn't had friends, I don't know what we would have done."
From early childhood, Marina was a wilful and opinionated girl. When cancer struck she insisted on taking charge of her own health.
Her mother said: "I was struggling alongside her for four years while she tried to go the alternative route. Now we have lost her I have begun to question so many of the things that we were convinced about. Even she had to admit that she had taken a calculated risk and lost. In one moment she burst out crying `It's not my fault, Mummy, if I'm dying'."
When the small dark mole on her foot was diagnosed as melanoma in 1994, Marina's doctors advised that the lymph nodes in her groin should be removed to reduce the chance of spread. She reluctantly agreed. She was a dancer and musician, living in San Francisco, and feared the effect on her legs, which she had been warned might swell. She was admitted to hospital and prepared for surgery.
But as she was being wheeled towards the operating theatre she leapt off the trolley and ran down the corridor and out of the hospital, crying: "I know I mustn't do this. It's wrong." For Marina, then aged 33, it was beginning of the end.
She was brought up in Kenya, and the family has homes in London and Europe, but she had moved to San Francisco where she had become a Buddhist and joined the alternative movement. She was learning to do healing massage.
By the time her mother arrived to join her at the beginning of her four- year battle against the cancer, she had amassed a vast quantity of information on alternative therapies and treatments.
With her mother, she went to the Gerson Institute in Tijuana, Mexico (it is not licensed to operate in the US) which charged $500 a day. Mirella said: "There are incredible stories of hopeless cases who have been given up by doctors and who have been cured by the Gerson Institute. They boggle the mind. But in order to succeed you have to follow this incredibly difficult diet . If you don't stick to it to the letter for two years, it doesn't work."
Marina stuck it for three months. The diet involved preparing and drinking eight ounces of freshly squeezed juices every hour on the hour and four "horrific" coffee enemas each day, to "de-toxify" the body, plus regular injections of liver extract and hormones.
"She did it as if she was going to war," said her mother. "I have never seen anyone bite the bullet as she did. Then one day she rang me and said: `Mummy, we have licked it.'
"Hospital tests had revealed no sign of the cancer in her blood."
The remission lasted almost a year. Marina visited the family home overlooking the Indian ocean on the Kenyan coast. "She was a completely changed person. She had escaped from the jaws of death. We all began breathing again," her mother recalled.
Marina returned to San Francisco and her life took off. Then, one evening in April 1997, the phone rang in the Ricciardis' Kenya home. Marina had been for a hospital test and the results showed that the cancer had returned: "She was screaming on the phone `Mummy, it's positive.' I will never forget that voice. One year after that phone call she was dead."
Mirella flew once more to San Francisco to support her daughter. Although still committed to the alternative route, Marina's opposition to orthodox treatment weakened as her desperation grew.
She underwent experimental vaccine therapy at the John Wayne Cancer Centre in Los Angeles, and also spent three weeks with her mother at the Institute for Optimum Health in San Diego, where they both drank wheatgrass juice and ate raw food.
Tumours were dug out of the lymph glands in Marina's groin, and X-rays showed that the cancer had spread to her lungs. She reluctantly agreed to undergo chemotherapy, but after the second dose the doctors told her that the treatment was not working.
Her mother Mirella said: "When the cancer returned, it came back with a vengeance. It took off, and devoured her."
By the time she made her final journey, last January to the Institute of Magnetic Therapy in the Dominican Republic, her mother knew it was too late. After three weeks, the institute sent her back to San Francisco and refunded the $10,000 cost of the treatment.
Mirella said: "I got a fax in Africa saying it had failed and she wanted to come back to Kenya to die at home. Then I got another fax saying she couldn't make it. I flew to San Francisco and there I found her covered in tumours. They were everywhere - on her stomach and on her neck. But she never lost her soul. She said to me one day, `My body is collapsing but my spirit is soaring.' But two days later she said: `Mummy, I don't want to go'."
Marina died on 15 March, 1998, having planned her own Hindu funeral and cremation. She gave each member of her family and her friends The Tibetan Book of Living and Dying, telling them: "I am just moving on."
From the start of her illness, she had been determined to prove the Western doctors wrong. Although the alternative therapies failed to defeat the cancer, she remained in control of her treatment.
Her sister Amina said: "Marina died with some dignity. It didn't work, but in the end it was not as bad as it might have been."