1. Normal Cells Gone Haywire
Our bodies contain billions of cells, the building blocks of life. Each cell receives messages from its chromosomes about how to grow and function. Sometimes, through genetics or environment, those chromosomes receive damage and send messages to the cell that caused a mutation. When normal cells in the body receive erroneous messages to grow and behave unchecked, a cancerous tumor can form.
2. Unchecked Growth
All cancerous tumors begin as a single damaged cell. That damaged cell divides into two cells, and two cancerous cells divide into four cells and so forth, until a tumor forms. However, a cancerous tumor can contain more than a million cells, yet still fit on the head of a pin. This period of undetected growth means that a cancer patient may harbor the disease for months or even years before it's detected. Researchers are developing better laboratory and imaging tests that can detect cancer at an earlier stage, which increases the chance of a cure.
3. Cancer Cells Can Travel
There's more to cancer cells than the fact that they multiply quickly. Unlike normal cells, cancer cells can travel to other parts of the body and create new tumors. Cancer cells break off from the main tumor, and then, once free, they spread through the bloodstream or lymphatic system and form tumors in different parts of the body. Doctors refer to this spread of cancer as metastasis.
4. Chip Off the Old Block
When a cancer patient receives a new diagnosis of cancer, the doctor must determine what kind of cancer it is before he can initiate treatment. Pathologists look at cancer cells under a microscope to determine where the cancer started, which is the primary site of the tumor. For example, if a patient has breast cancer, the cancer cells look like abnormal stomach cells under the microscope, not abnormal bone or lung cells. This is important if the cancer has metastasized, as the doctor treats the cancer according to the primary site. Therefore, if the breast cancer patient has tumors in the bone, the patient has metastatic breast cancer, not bone cancer. The cancer cells in the bone still resemble abnormal breast cells.
5. Aggressive or Slow Growing
Doctors can tell something about the behavior of cancer cells by examining how different they appear from the cells of their origin. If the cancer cells appear very abnormal, the doctors refer to them as poorly differentiated. These cancer cells grow and spread more quickly than tumors that appear similar to the tissue of origin. Doctors refer to these slower growing cancer cells as well differentiated.
