Does Sugar Really Feed Cancer?
The sugar-cancer connection has been a topic of debate in the oncology realm for decades. Despite a large body of published scientific literature showing an adverse relationship between elevated blood sugar (aka glucose) levels and cancer incidence, prognosis, and mortality, the established presence of excessive glucose receptors on the surface of cancer cells, the fact that our most sensitive cancer-finding scan is glucose-based, and a Nobel prize being awarded for describing cancers abnormal glucose metabolism, too many patients are hearing eat whatever you want, diet doesnt matter.
It does matter, in fact it matters a great deal.
The Nobel Prize was awarded to Otto Warburg for his discovery that cancer cells use a different type of metabolic process for producing energy than normal cells do. This cancer-specific metabolism is called aerobic glycolysis. Energy produced by aerobic glycolysis yields 2 units of usable cellular energy, called ATP, per molecule of glucose. One the other hand, normal cells use a type of metabolic energy production called oxidative phosphorylation. Oxidative phosphorylation occurs inside the mitochondria that are found within our cells. When one unit of glucose is metabolized via oxidative phosphorylation roughly 38 units of ATP are produced.
This means that cancer is 18 times less efficient at producing energy than normal cells. As a result of their energy producing inefficiency, cancer cells must substantially increase their uptake of glucose in order to meet their metabolic demands.
It is important to know that the definition of cancer is uncontrolled cellular division. Normal cells have a variety of mechanisms in place to make sure that they divide and reproduce only when needed, and stop dividing when appropriate. Cancer cells on the other hand, divide and reproduce in an accelerated and non-stop fashion. For a cell, the act of dividing and producing two new cells is a very energetically expensive endeavor. This uncontrolled and rapid division is the driving force behind cancers hunger for glucose. Cancer cells need more fuel to reproduce and they need more than normal cells do because their energy producing pathways are very inefficient.
One way that cancer cells try to increase their ability to utilize glucose has to do with glucose transporters. Glucose cannot simply move from the outside of a cell to the inside of a cell. Glucose needs to be shuttled into the cell via a specialized receptor called a glucose-like uptake transporter, or GLUT. In an attempt to increase their intracellular levels of glucose, cancer cells make more GLUT receptors. With more receptors to bring glucose into the cells, the more available glucose there is for the cell to fuel its rapid cellular division.
One of the most frequently used tools used to detect and monitor the presence of cancer in a persons body is the positron emission tomography scan, or PET scan. Before the actual scan is performed the patient is given a radioactively labeled IV solution. This radioactivity allows the substance in the IV to be seen inside the body when the scan is performed. The places in the body where the radioactivity localizes are areas of hypermetabolism, and very likely represent cancer. The intensity of the absorption of the IV material is referred to as Standard Uptake Value, or SUV. The higher the SUV, the more intensely the tissue is absorbing the IV solution. Cancer tissue absorbs the IV solution so intensely because it is something the cancer needs a lot of, namely glucose. The technical name for the radioactive IV solution given during a PET scan is 18F-2-fluoro-2-deoxyglucose, aka radioactively labeled glucose.
An inefficient energy metabolism, an increased number of glucose receptors on the cancer cell surface, and the demonstration of cancers rapid uptake of glucose by the PET scan all suggest that sugar/glucose has an important role in cancer development and cancer cell proliferation. Additionally, elevated glucose levels have also been found to influence a persons prognosis. Having an elevated blood glucose level has been found to be a negative prognostic indicator in many cancer types. As a negative prognostic indicator a higher glucose level can suggest a less favorable outcome and a more aggressive cancer. Both blood glucose levels and tumor SUV values have been studied for their usefulness in determining prognosis, and in both cases lower levels have been found to be advantageous.
What a person eats, or more importantly- what they dont eat, can have a big impact on their fight against cancer. To suggest that diet doesnt have a role in the treatment of cancer is to ignore a treatment that is relatively easy to implement, doesnt have an excessive cost, and has little potential for adverse effects. Combining a healthy cancer-specific diet along with a personalized integrative treatment plan is the best way to win the war against cancer.
Article contributed by Dr. Jonathan Psenka