About Cancer

What is Cancer, exactly?

According to World Health Organization estimates, cancer is the main cause of death for nearly 8 million people worldwide. In order to understand how cancer develops, the first thing we have to understand is that we have around 100 trillion cells in our bodies.  The total number of cells are regulated by not only controlling the rate of cell division, but also the rate of cell death. When cells are no longer needed, they will undergo a programmed signal leading to their death, in a process called apoptosis.  Once the cell receives this signals, it shrinks and eventually disassembles and is digested by our immune system.  Cells can also die as a result of injury, however, this form of extermination can result in a cell leaking its contents into its nearby environment. This spilling is not as “neat” as apoptosis and can cause swelling and inflammation. In humans, billions of cells die every hour and are continuously replaced with new cells.

Thus, programmed cell death is carefully balanced by the regeneration of new cells in healthy human beings.

The root of cancer lies in abnormalities in apoptosis (cell death). Usually, a cell will activate some of its genes, called oncogenes, that are responsible for growth and proliferation.  Of course the magnificent human body also contains its own antioncogenes, which suppress the activation of oncogenes. But sometimes patients lose or possess inactive antioncogenes, which can lead to cancer. Surprisingly,  we all have cells in our body that can mutate and cause cancer, but our immune system constantly regulates this number by digesting the cells that are deemed as potential risks.

Cancer cells are very invasive by nature because they do not possess regular growth limits, so they multiply at a rate much faster than normal cells.  They also float around the microenvironments, instead of adhering to a particular locations, which can form different sources for new cancer cells to grow. Some cells even secrete factors that recruit blood vessels and nutrients towards them, increasing their growth even more. Cancer cells also kill normal ones indirectly by competing for nutrients. In certain areas, cancer cells often outnumber normal ones, which can help them out-resource competitors, leading to the destruction of normal cells.

So if we are creating billions of new cells every day, why exactly aren’t we all at risk of having newly formed cancer cells? The answer to this question is that when cells replicate, they do so in a very precise manner. However, mutations occur due to the combination of chance and probability due to any previous genetic predisposition. Enough research has been done, however, to conclude that there are several external factors that can cause cancer in human beings.

• For one thing, certain chemicals called carcinogens have shown a large tendency to induce cell mutations that result in cancer. Cigarette smoke, for instance, is considered as the source for almost a quarter of all cancer deaths.
• Some types of food, which can damage the lining of our intestines and digestive tract can also cause cancer.  The exact mechanism is not known, but is believed to be involved with the rapid rate of cell regeneration, which introduces a higher rate of mutation.
• Radiation is also widely known to cause cancer due to the ions that can form in tissues as a result of gamma rays, x-rays, and other forms of particle infiltration that can denature DNA, and cause mutations.
• Hereditary predisposition is a strong reason for the development of cancer in a significant number of patients.  The cellular pathway that leads to cancer in persons that have a family history is much shorter than normal.  Generally, these  genetically exposed individuals have lesser defenses than the non-predisposed one, leading to a higher chance of acquiring the disease.

Source: Guyton et al. Medical Physiology. 11th ed. Saunders. Print.