We all love a sweet treat every now and then, but according to a new study, cancerous tumor cells tend to overdo it.

While there are many advanced cancer treatments today, the body's immune system can still deal with cancer on its own. The new research suggests that cancerous cells in tumors damage immune response cells by using up all of the sugar in the blood.

Tumors are known to redirect blood flow and encourage increases of sugar in the blood to promote their growth. Tumors will often grow around a high density of blood vessels to make sure that much of the blood's nutrients, including sugar, can get to cancer cells instead of normal cells.

However, the study suggests that this habit of tumors is not simply to promote their growth, but also to promote their safety from attacks by the body's immune system. The major part of the immune system that targets tumors are T cells.

T cells work by targeting disease-causing agents so that other cells in the immune system know to destroy the foreigners. They work by first binding to the foreign agent and then releasing inflammatory agents to mark the spot and call over other operative parts of the immune system to aid in destroying the agent.

To make inflammatory chemicals, the T cell needs sugar, as the inflammatory chemical is a byproduct of the cell's energy use. However, if a tumor is using up all of the nearby sugar, the T cell may get to the tumor, but never be able to release the chemical to alert the rest of the body so that it can be defeated.

During the study, T cells grown with and without tumor cells were tested for sugar utilization. Researchers found that in the absence of tumor cells, sugar levels were higher and there was more usage of the sugar by the T cells. They found that T cells grown with tumor cells did not utilize sugar at all, and there was nearly no sugar left in the experiment, indicating that the tumor had used all of it. However, the T cells did manage to survive the lack of sugar usage by using an alternate path for energy production. This alternate path allows the cells to survive without sugar, something which tumor cells cannot do.

Previous studies have shown that sugar deprivation causes almost immediate death in tumor cells. The lack of glucose in the tumor and surrounding normal cells causes an increase in blood oxygen levels. Oxygen is poisonous for tumors, as they cannot utilize the compound that normal cells use, ultimately dying from exposure.

A tumor's effects on T cells can be reversed. When T cells grown with tumor cells were given extra sugar, they functioned normally and made the inflammatory chemical to mark the tumor cell for destruction.

Perhaps the adaptability of T cells and rigidity of the use of sugar for tumor cells can be used to a cancer patient's advantage. The researchers found that without sugar, the T cells could survive but would not make the inflammatory chemical. This is important because if, during treatment, extra sugar is provided for T cells, they can continue to function normally.

Dr. Erika L. Pearce, Ph.D., an author on this study, said, "It's like an on-off switch, and all we need to do to flip it is change the availability of sugar," adding that T cells are adaptable and regain function in optimal conditions, "...we might be able to find a way to put the fight back into those T cells."

Source: Chang C, Curtis JD, Maggi LB, et al. Posttranscriptional Control of T Cell Effetor Function by Aerobic Glycolysis. Cell. 2013.