Fasting before chemotherapy, a standard treatment in many types of cancer, could lessen the dreaded side-effects that go with it.
A University of Southern California team led by Italian biologist Valter Longo found in mice experiments that 48-hour fasting could make healthy cells more resistant than cancer cells.
The discovery has been termed by many doctors as a breakthrough in the battle against tumors.
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.
"So far we have conducted experiments on mice and it worked. In the next six months we will have the results of tests on human cells," said Longo, who was very optimistic about these tests.
He noted, however, that the higher level of sophistication of the human body will cause the level of protection against chemotherapy less than that achieved in mice or yeast. "It is necessary to increase cellular resistance thousands of times as in the case of yeast. As human beings we hope to increase by twenty" said Longo, for whom this development will drastically improve treatments.