When cancer simply vanishes, could it be a key to a cure?

In her 28-year career, Dr. Deborah Axelrod, a New York physician, says she’s had just one patient whose advanced breast cancer inexplicably vanished.

The patient, Ann Fonfa, endured multiple surgeries to remove cancerous tumors that kept growing back. All the while, Fonfa refused the recommended treatments of chemotherapy and radiation, instead experimenting with unproven alternative therapies, including changing her diet, taking herbs and reducing stress.

Seven years after her original diagnosis, Fonfa received good news: The cancer was undetectable. Fonfa, 66, has been cancer-free for the last 14 years.

In a few rare cases, people defy cancer without medical treatment or by using therapies that are considered inadequate, a phenomenon known as spontaneous remission. Scientists have been fascinated and baffled by these developments for as long as cancer has been recognized as a disease. Was it luck? Or did the patients do something special to harness the awesome power of the immune system?

Studying these exceptional people, however, is fraught with difficulty, controversy and the dangers of promoting bad science. The potential benefits of highlighting the unusual recoveries should be balanced against the risks, experts warn, including offering patients false hope, blaming those who succumb and encouraging alternative treatments in place of conventional methods that could prolong or save lives.

“We have all heard or seen a few cases like this,” said Axelrod, of the Perlmutter Cancer Center at New York University Langone Medical Center. “I have also seen women die of neglected cancers, despite a fervent belief that they will be cured with a nontraditional treatment.”

The public hunger for new ways to fight cancer — along with the enormous gap in scientific evidence — is reflected in the recent best-selling book “Radical Remission” by Kelly Turner, a psychotherapist and independent researcher who wrote about nine factors she believes could play a role in spontaneous remission.

The best way to win the war on cancer, according to Turner, is to talk to those who have already won. “It’s only false hope if the stories are false,” she said. “But these people truly had cancer. And they are well now.”

Turner interviewed more than 200 people, including Fonfa, and analyzed more than 1,000 published cases. She found that those who heal from cancer without using conventional treatments — or after the treatments failed — had made significant lifestyle changes, such as radically altering the diet, using herbs and supplements, and embracing social support.

Medical experts say such observations aren’t very meaningful given the lack of a comparison group.

“For every person we hear about who refuses cancer therapy and lives, there are additional people who refuse standard medical therapy and die,” said Dr. Rebecca Johnson, a cancer specialist in the Seattle area who has also battled breast cancer. “There’s no way to count the latter number. Without formal scientific studies, it’s impossible to generate statistics on the efficacy of alternative treatments.”

Turner stresses that she is not suggesting that patients abandon standard medical interventions. Instead, she hopes to encourage further study and share the stories of people diagnosed with advanced cancer who experienced unexpected recoveries.

It’s impossible to know how often spontaneous remission occurs because physicians often don’t document or publish the cases, the patient may simply stop showing up at the doctor’s office, and most cancer patients in the past century have been conventionally treated in one way or another.

To date, the medical literature consists only of individual case studies and overviews. Some incidents, when more closely scrutinized, prove not to have been remissions at all.