When people hear the word cancer, they think of it as some “thing” in the body: a lump, a mass—the tumor. Look in a medical textbook, however, and you will find cancer defined as an abnormal and uncontrolled growth of cells—a process. To understand how these two are connected, we first need to understand some basic biology. The human body is made up of different parts, called organs, each performing a particular job that contributes to the functioning of the body as a whole; for example, the lungs bring oxygen to our blood and take away carbon dioxide, while the heart pumps the blood through the body.
These organs, and other kinds of tissue that make up the parts of the body, are likewise made up of smaller units, called cells. Normally, cells divide and mature, performing jobs that are programmed into their genes, until they age and die, usually to be replaced by new cells. A cell turns cancerous when something goes wrong in this process of cell division. A mutation alters one or more of a cell’s genes; the cell then starts to divide more rapidly than is normal, and the resulting cells fail to develop and perform properly. While normal cells have as part of their genetic programming instructions to die and to make way for new cells, cancer cells do not have this mechanism and continue to grow unchecked.
They accumulate to form a mass, or tumor, and then invade the normal tissue surrounding them, impairing or destroying its ability to function as well. Cancer cells can also spread, or metastasize, to other organs and areas of the body where this process of unchecked growth and harm is repeated.Depending on where it originates, cancer tends to grow and spread in characteristic ways. On the one hand, this makes it possible to define specific guidelines for the diagnosis, cancer staging, and treatment for each kind of cancer. But because of these differences, cancer is in reality over 200 different diseases.
Although medical science has grasped the basic biology underlying cancer as a process, the exact mechanisms for each type of cancer remain to be worked out. A number of factors can initiate the process of creating a malignancy: exposure to chemical and industrial compounds in the environment; medical drugs, such as some hormonal and immunosuppressive agents; radiation exposure; and lifestyle factors, particularly tobacco and alcohol consumption. Carcinogens are those agents that directly cause cells to grow in an abnormal manner, for example, by altering a cell’s DNA.
There are also cancer promoters and enhancers that either create conditions that contribute to cancer development or accelerate the abnormal growth of cells. Cancer development is a multistage process, and it takes a number of things to go wrong in order for the disease to take root and grow. That is why not everyone who smokes will develop lung cancer, even though there is no question of the carcinogenic potential of many of the chemical compounds contained in tobacco smoke.
When your loved one is diagnosed with cancer, it is natural to wonder: Why him or her? Why now? Because definite answers may not be found, people often focus on particular things they did, or didn’t do, or events that may have taken place just prior to diagnosis, or in the preceding months or years, that were in reality just coincidental with regard to the cancer.If you or your loved one thinks that a particular event or situation caused the cancer, discuss these impressions with the doctor directly to gain a better understanding of the possible contributors to the cancer development and growth.
Misconceptions about cancer often arise when people generalize or misapply what very well may be true in limited cases. For example, although there is a virus associated with the development of cervical cancer, the cancer itself is not contagious. In fact, there are very few other cancers that originate in infectious processes. In a similar vein, although there is a genetic component to many cancers, there are almost always other factors involved that result in cancer actually developing; for this reason, one cannot simply say that cancer is inherited.