A short period of fasting prior to chemotherapy may protect healthy cells but leave cancer cells vulnerable to drugs, according to a new study.
The results are very preliminary, based on animal research and a case study of just 10 people. But if they hold up, doctors could have a new tool for reducing chemotherapy's side effects and safely administering larger doses.
"Side effects aren't just, 'Will I lose my hair or not?'" said Valter Longo, a University of Southern California gerontologist. "It's, 'Will I be able to receive a high dose or not?'"
For the last decade, Longo has studied the effects of caloric restriction on cell function. In lab animals, diets with 25 percent fewer calories than normal are linked to extended, healthy lifespans. The mechanisms are poorly understood, but it seems that dietary stress activates cell-protecting mechanisms.
Longo's specialty is insulin-like growth factor 1, or IGF-1, a protein that regulates cell growth. Its production is limited during fasting. In yeast and roundworms, inhibiting IGF-1 has produced record lifespans. According to Longo, people who read about his work elected on their own to try fasting before chemotherapy. "We told them not to, their oncologists told them not to, but the patients went ahead and did it," he said.
Their accounts were gathered in a case report published in December in the journal Aging. Of 10 patients, six reported fewer side effects when they received chemotherapy while fasting, rather than while consuming food normally. Four received chemotherapy only while fasting, and reported fewer side effects than is typical. The effects of treatment did not appear to be altered at all.
In a paper published Monday in Cancer Research, Longo's team followed the human findings with a study of mice with cancer. Fasting reduced their IGF-1 levels. When given chemotherapy, none of the normal-diet control group survived, while 60 percent of fasting mice lived.
The findings are subject to many caveats. A mouse study is only a mouse study, few people were involved in the human study, and negative results may not have been reported. Still, the results have sparked further interest. In addition to his own ongoing clinical study at USC, Longo said the Mayo Clinic and Children's Hospital of Los Angeles are also planning tests.
Longo also started a company, L-Nutra, to develop a line of chemotherapy-tailored meals.
"I'd never tell patients to keep this in mind, but I'd tell the oncologists," said Longo. "If someone is out of options and suffering terribly, you have to keep in mind things that could make a difference, though there isn't a clinical trial with 2,000 people finished."
Image: Nic McPhee/Flickr
Citations: "Fasting and cancer treatment in humans: A case series report." By Fernando M. Safdie, Tanya Dorff, David Quinn, Luigi Fontana, Min Wei, Changhan Lee, Pinchas Cohen, and Valter D. Longo. Aging, Vol. 1 No. 12, December 31, 2009.
"Reduced Levels of IGF-I Mediate Differential Protection of Normal and Cancer Cells in Response to Fasting and Improve Chemotherapeutic Index." By Changhan Lee, Fernando M. Safdie, Lizzia Raffaghello, Min Wei, Federica Madia, Edoardo Parrella, David Hwang, Pinchas Cohen, Giovanna Bianchi, and Valter D. Longo. Cancer Research, Vol. 70 No. 4, February 15, 2010.