Fasting 'may be way to beat cancer'

Going without food for short periods may combat cancer and boost the effectiveness of treatments, an early animal study has suggested.

Fasting on its own slowed the growth and spread of tumours in mice, scientists found. When it was combined with chemotherapy, some serious cancers were cured. Researchers are already looking at the effects of fasting on human patients.

Results from a Phase I safety study looking at breast, urinary tract and ovarian cancers will be presented at a meeting in the US this summer. But only a clinical trial lasting several years will show if human cancer patients really can benefit from fasting, say the scientists.

They also warn that fasting could be dangerous for patients who have already lost a lot of weight or are affected by other risk factors, such as diabetes.

The research showed that tumour cells do not respond to the stress of fasting the same way as normal cells. Instead of entering a dormant state similar to hibernation, they try to keep growing and dividing. In the end the cells destroy themselves.

"The cell is, in fact, committing cellular suicide," said lead scientist Professor Valter Longo, from the University of Southern California in the US. "What we're seeing is that the cancer cell tries to compensate for the lack of all these things missing in the blood after fasting. It may be trying to replace them, but it can't."

The study is reported in the latest edition of the journal Science Translational Medicine.

Mice with five out of eight different types of cancer responded to fasting alone, the researchers found. Fasting without chemotherapy slowed the growth of breast cancer, melanoma skin cancer, glioma brain cancer and neuroblastoma. In every case, combining fasting with chemotherapy made the cancer treatment more effective.

Multiple cycles of fasting combined with chemotherapy cured 20% of mice with a highly aggressive type of children's cancer that had spread around the body. Mice with a more limited spread of the same cancer were cured in 40% of cases.

None of these mice survived if they were treated with chemotherapy alone, said the scientists. Fasting also extended the survival of mice with a human ovarian cancer.