 Cancer in one way or another has affected most people – maybe a friend or relative has been diagnosed with it, or maybe you yourself are a survivor. Because of its pervasiveness in American culture, it’s important for you to have a basic understanding of what cancer is, what causes it, and how it can be prevented.
A Lesson in Cell Division and Death
Cancer is a term used to describe more than 100 diseases, all of them relating to your body’s most basic life form – the cells. Normally, there’s a delicate balance between cell death and cell growth. When the balance is disrupted, cancer occurs. The imbalance is caused when:
- Damaged cells don’t commit suicide as they should, and instead reproduce themselves. Normally, old or damaged cells self-destruct (called apoptosis or cell suicide). Apoptosis is how your body rids itself of old or damaged cells. When this process does not occur, the old or damaged cells are left to divide and reproduce duplicates of their defective selves. Figure 1 compares normal cell division with division of abnormal cells.
- Cells multiply when new cells are not needed. In normal tissues, new cells form only to replace the ones that have died. Using skin cancer for illustrative purposes, figure 2 shows the normal process of cell growth. Cells divide just fast enough to replace the cells being shed from the outer surface. When cells divide at an accelerated rate, a mass of tissue forms (called a tumor or neoplasm). The faster the cells divide, the faster the tumor grows.
Not All Growths Are Cancer
Normally, cell structure and arrangement are orderly. When more and more cells accumulate, the normal structure and arrangement is altered, illustrated in Figure 3. While a growth due to too many cells is abnormal, not all cell growths are cancerous. No one knows for sure why some growths are cancerous and others are not, but researchers believe it has something to do with multiple gene mutations.
 Abnormal cell growth can cause tumors that are benign (not cancerous) or malignant (cancerous). Benign tumors can often be removed and do not come back. Cells from benign tumors are self-contained (they do not spread). When the cells in a tumor are abnormal, and divide without control or order, they are cancerous. Cells from malignant tumors can damage nearby tissues, and can spread throughout your body.
Figure 4 compares various abnormal cells growths to normal cell division:
- Normal cells die and divide at equal rates.
- When cells begin to multiply out of control, the cell structure and arrangement maintain their shape and order (hyperplasia). This non-cancerous condition can be a normal tissue response, such as when you form a callus.
- Another non-cancerous condition is dysplasia – the normal tissue arrangement or cells structure is altered, but maybe not permanently.
- Severe dysplasia is sometimes called “carcinoma in situ” or an uncontrolled cell growth that remains in its original location – it hasn’t spread.
- Finally, the abnormal cells spread, either by direct migration and penetration into normal cells (invasion) or by penetrating the lymphatic system and blood vessels, circulating through the bloodstream, and invading normal cells elsewhere in your body (metastasis).
Early detection can decrease your risk of death from cancer. Cancer does not always present symptoms in the early stages. That’s why routine screenings are so important. |
