Furthermore, fasting on its own was shown to be effective at treating most of the cancers tested in animals, including human cancer cells.
The researchers discovered that 5 out of 8 types of cancer in rodents responded to fasting alone. Fasting, like chemotherapy, delayed the growth and spread of tumors.
Senior author Valter Longo, professor of gerontology and biological sciences at the University of Southern California, explained: and without exception, "the combination of fasting cycles plus chemotherapy was either more or much more effective than chemo alone."
For instance, 20% of mice with highly aggressive type of children's cancer that had spread throughout the organism were cured with several cycles of fasting in conjunction with chemotherapy, while 40% of mice with a more limited spread of the same cancer were cured. No mice in either case survived with chemotherapy treatment alone.
Longo warned that only a human trial that lasted several years would be able to show if humans would benefit from the same treatment.
Results from a phase I human trial involving individuals with ovarian, breast and urinary cancer, have been submitted for presentation at the annual meeting of the American Society of Cancer Oncologists. The study was carried out at the USC Norris Comprehensive Cancer Center and led by oncologists Tanya Dorff and David Quinn, in collaboration with Longo.
Only the safety of a therapy, in this case if individuals can tolerate fasts for two days before and one day after chemotherapy, were tested in the first phase.
"We don't know whether in humans it's effective. It should be off limits to patients, but a patient should be able to go to their oncologist and say, 'What about fasting with chemotherapy or without if chemotherapy was not recommended or considered?"
In 2010, a case report study with self-reported data, published in the journal Aging, revealed that 10 individuals with cancer who tried fasting cycles experienced less adverse effects from chemotherapy.
According to Longo, fasting may not be a safe option for everyone. The human trial did not include cancer patients who had risk factors, such as diabetes, or had already lost over 10% of their normal weight. In addition, fasting can result in headaches and lower blood pressure, which for some patients could make driving and other activities dangerous.
The researchers found that in mice, fasting cycles without chemotherapy could delay the growth of melanoma, glioma, human neuroblastoma and breast cancer. They discovered that in multiple cases, fasting cycles were as effective as chemotherapy.
In addition, fasting prolonged survival in mice bearing human ovarian cancer. The researchers found that in mice with melanoma, the cancerous cells became resistant after a single round of fasting alone, however just one round of fasting demonstrated to be as effective as chemotherapy in lowering the spread of cancer to other organs in the body.
For all cancers the researchers tested, they found that chemotherapy combined with fasting delayed tumor growth and/or limited the spread of tumors, and improved survival.
The researchers found that although the growth of large tumor masses decreased with several fasting and chemotherapy cycles, cancer-free survival could not be achieved. Longo believes that cells inside a large tumor could be protected in some way, or that the different mutations in a large tumor may make it more adaptable.
Longo said that in the majority of cancer patients, oncologists have at least one opportunity to fight the cancer before it grows too large.
In order to try to understand the effects of fasting, Longo and collaborators at the National Institute on Aging researched in detail, one type of breast cancer.
They found that cancer cells deprived of nutrients attempted to generate new proteins and took steps to keep growing and dividing, while normal cells enter a state similar to hibernation.
According to Longo, the result was a "cascade of events" that resulted in the generation of damaging free radical molecules, which broke down the cancer cells' own DNA and caused their destruction.
"the cell is, in fact, committing cellular suicide. 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 supports a previous study by Longo's team published in Proceedings of the National Academy of Sciences in 2008.
In that study, the researchers demonstrated that fasting protected normal cells against chemotherapy, although they were unable to address the effect on cancer cells. In addition, the study only focused on a single chemotherapy drug and cancer.
However, the new study demonstrates that fasting fails to protect cancer cells, although it makes them more vulnerable, an effect Longo calls "Differential Stress Sensitization".
Longo's interest in cancer and fasting derives from years of research on the beneficial effects of fasting in yeast and other organisms. 15 years ago, Longo demonstrated that starved yeast cells enter a stress-resistant mode as they wait for nutrition.
Longo said: "by contrast, the mutations in cancer cells come at a cost, such as a loss in adaptability to diverse environments." For instance, he discovered that yeast genetically modified to mirror cancer cells become considerably more sensitive to multiple toxins.
"A way to beat cancer cells may not be to try and find drugs that kill them specifically but to confuse them by generating extreme environments, such as fasting that only normal cells can quickly respond to."
Longo's collaborators were lead authors Changhan Lee, a graduate student in Longo's laboratory at the USC Davis School of Gerontology, and Lizzia Raffaghello, a researcher at the Giannina Gaslini Institute of Genoa, Italy. Other co-authors were Min Wei, research assistant professor in gerontology at USC; Sebastian Brandhorst, Fernando Safdie, Saewon Hwang and Annalisa Merlino, researchers in the Longo lab; Giovanna Bianchi, Laura Emionite and Vito Pistoia of the Giannina Gaslini Institute; and Alejandro Martin-Montalvo and Rafael de Cabo of the National Institute on Aging.
The National Institutes of Health, the Bakewell Foundation, The V Foundation for Cancer Research, the Norris cancer center, the Italian Association for Cancer Research and the Italian Foundation for Cancer Research, funded the study.
Written by Grace Rattue