Short-term fasting improved the effectiveness of radiation therapy in and expanded the life expectancy of mice with aggressive brain tumors, according to a study published by USC researchers Tuesday.

This is the first study to show that fasting affects the treatment of cancer cells with radiation treatment. The study’s co-author Valter Longo, professor of gerontology and biological sciences and director of the Longevity Institute at the USC Davis School of Gerontology, previously conducted research on chemotherapy treatment and reported similar findings.

Researchers studied the treatment of mice infected with glioma, the most commonly diagnosed and one of the most aggressive brain cancers, examining the effects of radiation therapy on both cancerous and noncancerous cells.

“One of the things we saw was if we make a cancer-like cell, it becomes much more sensitive to anything when it’s under starvation conditions,” Longo said. “It becomes confused and doesn’t know how to adapt.”

The study showed that fasting in periods of no more than 48 hours improved the effectiveness of radiation in treating glioma cells. Though healthy cells go in “to a protective mode” as a result of the fast, Longo said cancer cells are unable to adapt and protect themselves from the radiation therapy.

“When you starve a cell, what happens is there’s more of an effect on the tumor cells than there is on a normal cell because the tumor cells are rapidly deteriorating,” said Thomas Chen, co-director of the USC Norris Neuro-Oncology Program and a co-author of the study. “When we starved the animals before giving them the chemotherapy, what we’ve done is we’ve made the tumor cells more susceptible because they don’t have as much energy or access to glucose as they normally do.”

Chen said that, although glioma is not curable, the mice who fasted during their treatment lived longer than those who did not fast as well those who only fasted.

“What we have from the animals looks very promising from the combination of the starvation diet with chemotherapy,” Chen said.

Longo said some glioma patients have already tried fasting in addition to their chemotherapy or radiation therapy, but he does not recommend patients use the treatment without medical supervision.

Chen noted that his plans to do a clinical trial in the future will likely run into difficulties with the fasting itself.

“It’s hard for patients to comply with. It’s hard for the patients to say, ‘I’m not going to eat before my chemotherapy,’” Chen said. “One of the things that we’re doing is basically making up a diet so that you can eat something and not feel so bad and basically have a low caloric intake.”

Chen said the unorthodox nature of this treatment could assist in treatment of glioma in human patients because the current standard treatment, orally ingesting the chemotherapy drug Temozolomide, is a slow process that loses effectiveness once the drug has reached the brain. Combining this traditional treatment with a starvation diet, and therefore a weakening of cancer cells, could improve the effectiveness of treatment.

“The drug itself … is not as effective as it can be,” he said. “Any kind of help along, like the starvation diet, will probably help the patient.”