However, senior author, Valter Longo, cautions that only a clinical trial lasting several years will be able to show if humans are able to benefit from the same treatment. He believes without exception, “the combination of fasting cycles plus chemotherapy was either more or much more effective than chemo alone.”
In animals at least, the study implies that cancer cells are vulnerable when attacked by chemo coupled with cycles of fasting. Even fasting on its own appears to treat many cancers tested in animals, even in those derived from human cells. The study demonstrates that five out of eight cancer types in mice responded to fasting alone: it slowed the growth and spread of tumors.
For the study, which involved cancer cells and mice, Longo and associates found that for all the cancers they tested, fasting combined with chemotherapy improved survival, slowed tumor growth and/or limited tumor spread. They also discovered that fasting without chemotherapy was able to slow the growth of breast cancer, melanoma, glioma, and human neuroblastoma. In a few cases, fasting was found to be as effective as chemotherapy.
However, the study also revealed that cancer cells are capable of developing resistance to fasting. In the case of melanoma, this happened after only one cycle of fasting. The researchers say that one fasting cycle was just as effective as chemo in slowing the spread of cancer to other organs. They also found that fasting extended survival in mice with human ovarian cancer.
To determine the effect fasting has on cancer cells, Longo and fellow researchers studied one type of breast cancer in detail. When normal cells are deprived of nutrients, they go into a dormant state, similar to hibernation. But in the case of cancer cells, Longo realized this is not occurring; instead they try to make new proteins and look for other ways to grow and divide. They then observed a series of events that resulted in damaging free radicals destroying cancer cells by breaking down their DNA.
Longo theorizes that a possible way to beat cancer cells is not to try and find drugs that selectively destroy them, but to instead, "confuse them by generating extreme environments, such as fasting that only normal cells can quickly respond to.”