April 04, 2008
|Pre-Chemo Fasting May Protect Healthy Cells||Health Science/Technology|
One of the reasons it's hard to kill cancer is that it's hard to create treatments that distinguish between cancer cells and normal cells, so it's hard to kill cancer without also killing the patient. Most chemotherapy agents broadly target all cells that are dividing, on the theory that cancer cells divide more often than most normal cells so you'll kill more cancer cells on average. But lots of normal cells become collateral damage in the process, leading to the well-known toxic side-effects of chemo. Hair follicle cells and cells lining the intestinal tract divide especially rapidly, which is why hair loss and nausea are common.
Ideally, the body's own immune system would kick in and selectively kill cancer cells, but there's a problem. The immune system is very good at detecting foreign invaders, but cancer cells are the body's own cells — good cells gone bad — so their external markers are largely indistinguishable from those of normal cells. A lot of research has gone into finding ways to differentiate between normal cells and cancer cells in the hopes of creating "targeted" therapies — chemotherapy agents that attack only cancer cells — but success, so far, has been very limited.
Some researchers have taken an entirely different tack: instead of trying to detect which cells are which and attack only cancer cells, find instead a way to protect healthy cells against chemotherapy. And it turns out there may be a very simple, drug-free way to pull this off. USN&WR:
Fasting for two days before chemotherapy might protect cancer patients against the toxic side effects of these powerful drugs by shielding healthy cells while dooming malignant cells to destruction, new research suggests. [...]
Although not yet replicated among patients, the preliminary animal research is encouraging: As little as 48 hours of starvation afforded mice injected with brain cancer cells the ability to endure and benefit from extremely high doses of chemotherapy that non-starved mice could not survive.
The finding was published in the March 31 online issue of the Proceedings of the National Academy of Sciences.
Longo noted that the idea first came from a different field of research: anti-aging science.
"We had found that healthy cells have a 'shield mode' -- a kind of protective strategy that allows the organism to be resistant to not just one but dozens of threats and stresses, including starvation," he said. "So we thought this characteristic might be a way to distinguish between normal cells and cancer cells when applying chemotherapy. And it turns out that it works for yeast, for human cells in test tubes, and here, in mice."
Following genetic manipulation of yeast to show that mimicking starvation could confer a life-prolonging protection against stress, the researchers induced glucose deprivation among a series of rat and human cell lines, some cancerous, some healthy.
This protected the healthy cells against exposure to toxic compounds, while leaving cancer cells unprotected.
In turn, the researchers then tested mice injected with brain cancer cells to see how they faired upon exposure to a high dose of the chemo drug etoposide. Noting that just one-third of this amount is considered to be the maximum for what is allowable for human treatment, Longo and his team compared results among mice starved for 48 hours and 60 hours pre-treatment with mice that were not starved.
While 43 percent of the non-starved mice died within 10 days of treatment, only one of the 48-hour starved mice died in that time. As well, while starved mice had lost 20 percent of their weight before treatment, most regained it back within four days of chemo exposure while the non-starved mice actually lost 20 percent of their weight post-treatment.
Non-starved mice also suffered toxic side effects, such as impaired movement, ruffled hair and poor posture. The 48-hour starved mice displayed no such problems.
Mice starved for 60 hours were exposed to even higher chemo doses. At that level, all non-starved mice died by the fifth day, at which point all the starved mice continued to survive. Again, almost all starvation weight loss was regained post treatment, and no signs of toxicity were evident.
Longo and his colleagues concluded that short-term starvation does appear to guard healthy cells and allow cancer treatment to attack only diseased cells. They said they are now organizing a human trial.
"We hope this works with patients, and we have reason to think it will," he said. "I think I'm more enthusiastic about this than anything else I've done. And you can see the potential for this being turned into something very, very useful. But we won't know until we do it."
Dwayne Stupack, an assistant professor of pathology with the Moores Cancer Center at the University of California, San Diego, described the current effort as a "reasonable" approach toward mitigating the undesirable effects of chemotherapy.
"We all know that people can go for a few days without eating, and it's not going to kill them, because the cells in our body are able to adjust and make do," he noted. "It's an intrinsic evolutionary stress response that is designed to keep those cells alive. And it turns out that this response also works to keep those healthy cells alive during chemotherapy."
"So, I think what they've done is very interesting and exciting, in the sense that the tumor they looked at is very aggressive, very lethal, and they were able to use what I would call relatively high chemotherapy without causing toxicity -- because the cells have already been conditioned to sort of shut down," Stupack said.
Stupack cautioned, however, that the starvation technique might not work for everyone. "There are certain tumors that may already be altering metabolism to normal tissue, and certain populations of cancer patients among whom an intrinsic stress response to the cancer is already under way," he noted. "In these cases, this approach might not achieve anything further. Those are the kinds of limitations that should be considered."
Very interesting, obviously. And it's free, non-toxic, and largely harmless. It will be interesting to hear what my oncologist has to say about it. One possible issue: getting chemo is an unpleasant process as it is. How much worse will it feel when one is ravenously hungry? Still, if it works...
I forget how long chemo sessions last, but it sounds like you get to eat right after, no? It would be nice if you could sleep during the chemo to black out the whole experience.
The human body never seizes to amaze me. On the surface, one might conclude that a two-day starvation would weaken the body making it less capable of fighting the negative effects of chemo treatments. I mean 48 hours without food and the backup generators are powering the body. Yet, it appears starvation in all its simplicity has a few potent tricks up its sleeve. It makes me wonder just how much of a role our eating habits may play in the onset of cancer.
Posted by: at April 5, 2008 02:57 AM
I think "fasting" would be a more positive term than "starvation" when promoting this pre-treatment prepping.
But this article makes a lot of sense. Fasting has been used for centuries in many religions as a way of purifying the body and spirit. To me, it's prudent to rid one's self of toxins before bringing in another truckload.
And I agree with the previous commenter that our eating habits play a key role in our vulnerability to cancer. Nutrition and environment. May not always be able to control our surroundings, but we can make intelligent choices in our diets.
"Glucose deprivation" is mentioned. Cancer loves sugar. And probably has an obsession for high fructose corn syrup.
Posted by: Lane_in_PA at April 5, 2008 05:13 PM
The few times I've fasted I've found that the hunger backs off and is replaced by a wonderful kind of energy, an intense alertness. I don't remember the timeline, but I think the effect has begun within 48 hours.
The time I did a 7 day fast on fresh lemon juice, maple syrup and cayenne pepper (in water), I didn't really want to break it, I was feeling very light and quick, eating returned a heavier, full feeling.
Posted by: Kent at April 6, 2008 05:44 PM
While researching alternative therapies myself to fight an autoimmune disease, I found this article on muscles. Traditionally thought of as nothing more than the component of our body that provides mobility, new research is showing that our muscles play a much bigger role in our overall health, even going as far as keeping disease at bay (including cancer). Stronger muscles, to a point, do a better job of protecting us then weaker muscles, so this researcher recommends lifting weights. On top of the American Heart Associations recommendation that all adults (even healthy ones) capable of safely lifting weights should do so, it makes you think.
Posted by: at April 6, 2008 10:29 PM