Can restricting calories starve cancer cells into remission?
New research, involving laboratory mice, suggests chemotherapy drugs work much better when they are preceded by brief periods of fasting.
Cancerous tumours, made up of millions of rapidly dividing cells, are essentially big energy hogs.
"They need to burn lots of energy just to stay alive," explains the senior researcher, Valter Longo at the University of Southern California.
So cutting off their source of nourishment can put them in an extremely vulnerable position, he added.
For the study, some of the mice received no food for two days before chemotherapy. They were given only water to prevent dehydration. As a result of fasting, blood glucose levels dropped by 50 per cent. What's more, there was a 70-per-cent plunge in Insulin-like Growth Factor 1 (IGF-1) – one of several key ingredients required for tumour growth.
Normal healthy cells can tolerate brief periods when nutrients are in short supply. They essentially enter a dormant state, similar to hibernation, Dr. Longo said.
But cancer cells, programmed for unrelenting growth, no longer have the capacity to rest, and they begin to shows signs of collapse.
A blast of chemotherapy, when they are in this weakened state, appears to push some tumours over the edge, according to the findings published this week in the journal Science Translational Medicine.
Dr. Longo noted that fasting plus chemotherapy is more effective than chemo alone for fighting a wide variety of different cancers in mice.
It will now take a large clinical trial lasting several years to determine whether this approach also works in humans.
Dr. Longo and his fellow researchers have nearly completed a small study to determine whether cancer patients can tolerate fasting. In this trial, patients abstained from food for three days before receiving chemotherapy and continued fasting for one additional day. Like the mice, they consumed only water.
The preliminary evidence looks promising, but Dr. Longo cautioned that fasting may not be safe for everyone, especially those with other medical conditions such as diabetes.
Fasting can cause a drop in blood pressure, headaches and other adverse reactions. And if fasting lasts too long, the patient's immune system may suffer and give the cancer the upper hand once more. So, medical teams will have to closely monitor patients involved in clinical trials. "It would be very dangerous for patients to start doing this on their own," he warned.