1. Cancer
Chapter 2 Section 4

2. What is Cancer?
When you think about cancer, you can relate it to planting a beautiful garden with some ground ivy to fill in spots. What happens once the garden begins to grow is that your ground ivy will take over the garden. Beautiful flowers will become entangled by vines which will strangle many of your plants. The ivy will use up more than its share of garden space and soil nutrients.
This is similar to what cancer does to our bodies.
The ivy will grow uncontrollably and destroy the other plants like cancer destroys the parts of our body around it.

3. Cancer
Cancer is a disease in which cells grow and divide uncontrollably, damaging the parts of the body around them.
Cancer is not just one disease.
In fact, there are more than 100 types of cancer.
Cancer can occur in almost any part of the body.
Cancers are often named by the place in the body where they begin.
In the US today, lung cancer is the leading cause of cancer deaths among men and women.

4. How Cancer Begins
Scientists think that cancer begins when something damages a portion of the DNA in a chromosome.
The damage to the DNA can cause cells to function abnormally.
Normally, the cells in one part of the body live in harmony with the cells around them.
Cells that go through the cell cycle divide in a controlled way. Other cells don’t divide at all.
Cancer begins when mutations disrupt the normal cell cycle, causing cells to divide in an uncontrollable way.
The cells stop behaving as they normally do.
Without normal controls on the cell cycle, the cells grow too large and divide too often.

5. How Cancer Spreads At first, one cell develops in an abnormal way.
As the cell divides, more and more abnormal cells like it grow near it.
In time, these cells form a tumor.
A tumor is a mass of abnormal cells that develops when cancerous cells divide and grow uncontrollably.

6. Tumors Tumors often take years to grow to a noticeable size.
During that time, the cells become more and more abnormal as they continue to divide.
Some of the cancerous cells may break off the tumor and enter the bloodstream.
In this way, the cancer can spread to other areas of the body.

7. Treating Cancer
If a person is stricken with cancer, there are a variety of treatments that may be effective in fighting the disease.
Doctors usually treat cancer in one or more of three ways: surgery, radiation, or drugs that destroy the cancer.

8. Detection of Cancer
When cancer is detected before it has spread to other parts of the body, surgery is usually the best treatment.
If doctors can completely remove the cancerous tumor, a person may be cured of the disease.
If, however, the cancer has spread or if the tumor cannot be removed, doctors may use radiation, beams of high-energy waves.
Fast growing cancer cells are more likely than normal cells to be destroyed by radiation.

9. Chemotherapy
Chemotherapy, or the use of drugs to kill cancer cells, is another form of treatment.
Chemotherapy is effective because the drugs spread throughout the body, killing cancer cells or slowing their growth.

10. Side-Effects of Cancer Treatment
Unfortunately none of these cancer treatments is perfect.
Most have unpleasant, or even dangerous side-effects.
Scientists continue to look for new ways to treat cancer.
If, for example, scientists can discover how the cell cycle is controlled, they may find ways to treat cancer.
They might be able to “turn off” cancer before it causes too much damage to the body

11. Cancer Prevention
Scientists estimate that a two thirds of all cancer deaths are caused either by tobacco use or unhealthy diets.
Smoking is the main cause of lung cancer.
When people repeatedly expose their bodies to the chemicals in tobacco, their cells will likely become damaged and cancer will result.

12. Unhealthy Diets
It might surprise you to learn that unhealthful diets may lead to almost as many cancer deaths as tobacco does.
A diet high in fat is especially harmful.
Regularly eating high-fat foods, such as fatty meats and fried foods, can put a person at risk for cancer.
A diet that includes fruits, vegetables, and grain products can help lower a person’s risk of some types of cancer.