Yesterday, my mother (not a rationalist) told me that she had recently heard somewhere (most likely on a popular television program) that, as simple as it sounds, an effective cancer treatment is cutting back on glucose intake. According to her story, cancer cells can only efficiently use glucose as fuel, and will be unable to multiply (or will starve, or something like that) if you don't consume any. Meanwhile, normal cells can convert other forms of energy into glucose inside their membranes, and then will continue functioning normally.
My first two thoughts:
Reality just can't be that nice.
Hey, wait a second, doesn't the body just convert everything into glucose before it's released into the bloodstream, anyways?
So I did some Googling and I found out that what my mother was referring to is called a ketogenic diet (from Wikipedia):
The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that in medicine is used primarily to treat difficult-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are converted into glucose, which is then transported around the body and is particularly important in fuelling brain function. However, if there is very little carbohydrate in the diet, the liver converts fat into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an energy source. An elevated level of ketone bodies in the blood, a state known as ketosis, leads to a reduction in the frequency of epileptic seizures.
So, prima facie, my second objection was dealt with. More Googling led me to discover these two references to what my mother had mentioned:
- The paper mentioned in the blog post, "The Ketogenic Diet and Hyperbaric Oxygen Therapy Prolong Survival in Mice with Systemic Metastatic Cancer".
According to the paper:
Abnormal energy metabolism is a consistent feature of most tumor cells across all tissue types . In the 1930 s, Otto Warburg observed that all cancers expressed high rates of fermentation in the presence of oxygen . This feature, known as The Warburg Effect, is linked to mitochondrial dysfunction and genetic mutations within the cancer cell , , . These defects cause cancers to rely heavily on glucose for energy, a quality that underlies the use of fluorodeoxyglucose-PET scans as an important diagnostic tool for oncologists . Ketogenic diets are high fat, low carbohydrate diets that have been used for decades to treat patients with refractory epilepsy . Ketogenic diets also suppress appetite naturally thus producing some body weight loss , , , . Dietary energy reduction (DER) lowers blood glucose levels, limiting the energy supply to cancer cells, while elevating circulating blood ketone levels . Ketone bodies can serve as an alternative energy source for those cells with normal mitochondrial function , , but not for cancer cells . DER has been shown to have anti-tumor effects in a variety of cancers, including brain, prostate, mammary, pancreas, lung, gastric, and colon , , , , , , , , , . DER produces anti-cancer effects through several metabolic pathways, including inhibition of the IGF-1/PI3K/Akt/HIF-1α pathway which is used by cancer cells to promote proliferation and angiogenesis and inhibit apoptosis , , , , , , , . Additionally, DER induces apoptosis in astrocytoma cells, while protecting normal brain cells from death through activation of adenosine monophosphate kinase (AMPK) .
Note what the sentence with ten citations says. Why have I never heard of this? If the basic claims being made are true, we seem to have an effective way of at least preventing cancer from progressing further (if not killing it off), and it's not even dangerous (at least compared to the alternatives, as far as I am aware of...however, I realize I know next to nothing in this field...that's the reason for this post)! Is there some reason this isn't being sung about on Reddit as a huge victory for science? What is the counterevidence? Or are we still waiting for more research to be done?
For genetic reasons and because humans often engage in motivated reasoning, I am skeptical. I am querying the Less Wrong community for more information...perhaps some of you have already heard of a ketogenic diet being used as a cancer treatment, or would like to do more research than I've done now that I've introduced you to it. The following books may also serve as helpful, albeit expensive, references:
- Cancer as a Metabolic Disease: On the Origin, Management, and Prevention of Cancer by Thomas Seyfried. I think this would be the "standard" reference here.
- The Cantin Ketogenic Diet: For Cancer, Type I Diabetes & Other Ailments by Elaine Cantin.
- Ketogenic Diets by Dr. Eric H. Kossoff (and others).