Index
Over half a million people die of cancer in the United States every year. Cancer is the second leading cause of death after heart disease, according to the Centers for Disease Control and Prevention (CDC). More than 7 million people die of cancer every year worldwide.
What is cancer?
Cancer is a disease caused by cells that become abnormal and start to multiply uncontrollably.
The abnormal cells may invade other tissues and cause the cancer to spread (metastize).
Invasive cancers that grow aggressively and metastize are called malignant, whereas
abnormal growths that remain localized are called benign.
Cancers are usually classified by the types of tissue that they affect. The following table shows the estimated annual incidence of the most common cancers for 2008, according to the American Cancer Society.[1]
| Cancer Type |
Estimated New Cases |
Estimated Deaths |
Percent Mortality |
|---|---|---|---|
| Skin (non-melanoma) | >1,000,000 | <1,000 | 0.1% |
| Lung (Including Bronchus) | 215,020 | 161,840 | 75% |
| Prostate | 186,320 | 28,660 | 15% |
| Breast (Female) | 182,460 | 40,480 | 22% |
| Colon and Rectal (Combined) | 148,810 | 49,960 | 34% |
| Bladder | 68,810 | 14,100 | 20% |
| Non-Hodgkin Lymphoma | 66,120 | 19,160 | 29% |
| Melanoma | 62,480 | 8,420 | 13% |
| Kidney (Renal Cell) Cancer | 46,232 | 11,059 | 24% |
| Leukemia (All) | 44,270 | 21,710 | 49% |
| Endometrial | 40,100 | 7,470 | 19% |
| Pancreatic | 37,680 | 34,290 | 91% |
| Thyroid | 37,340 | 1,590 | 4% |
Although skin cancer is by far the most common, lung cancer, which is the second most common, is deadlier. Pancreatic cancer has the worst prognosis; it is fatal 91% of the time.
What causes cancer?
Normal cells work in concert by communicating through chemical signals that are recognized and interpreted
by the genetic material within each cell. When a cell becomes damaged, a process
called apoptosis kills the cell by breaking it up into components that can be recycled for use by
the body. The action of a protein called p53 can trigger apoptosis from within a cell, but
cells from the immune system or the surrounding tissue may also trigger apoptosis.
Interfering with the p53 protein of a cell may supress the apoptotic capability of the cell.
Cells that lose the ability to undergo the programmed death of apoptosis can start
reproducing without inhibition and form a tumor.
The chemicals in tobacco and tobacco smoke modify cellular structures. Persons who smoke cigarettes and chew tobacco have greater cancer rates than persons who don't use tobacco. Other risk factors for cancer include obesity, exposure to asbestos, some viruses, chemical mutagens, excessive sunlight, and hereditary genetic predisposition to cancer. Excessive alcohol consumption is associated with increased risk of oral and esophageal cancers.
| Type of Cancer | Risk factors |
|---|---|
| lung cancer | cigarette smoking; exposure to asbestos, uranium and nickel |
| skin cancer | excessive exposure to the sun, tanning salons |
| breast cancer | familial history - genetics |
| cervix cancer | human papilloma virus exposure |
| colon and rectum | high fat diet, low fiber |
| oral cancer | alcohol plus smoking, smokeless tobacco |
| urinary bladder |
aniline dye exposure, cigarette smoking, exposure to parasite Schistosoma haematobium |
| leukemia | exposure to benzene, ionizing radiation |
Steps to Prevent Cancer
The onset of cancer usually takes a long time, but after it develops, it may spread very fast.
Twenty years may elapse before a smoker starts showing signs of cancer.
To prevent or reduce the chance of cancer, it is necessary to avoid exposure to harmful chemicals,
radiation, and viruses, while maintaining good nutrition to keep the immune system working optimally.
This can be summarized by three rules:
- Don't smoke cigarettes or chew tobacco. The major cause of lung cancer is smoking. Tobacco smoke has many carcinogenic chemicals. You can reduce this risk by not smoking and by avoiding bars and smoky places where you can be exposed to second-hand smoke. Lung cancer may also be caused by inhaling asbestos dust. Asbestos was used as an insulating material in old buildings. Avoid dusty home remodeling or construction jobs that may expose you to asbestos particles.
- Don't get sunburned. Exposing the skin to the sun produces Vitamin D that helps to build strong bones. However, too much sun can burn the skin and cause cataracts. Sunbathing and excessive exposure to the sun is the most common cause of skin cancer. The use of sun block can protect the skin from burning, but it also blocks the ultraviolet rays that make Vitamin D. Exposure to the sun should be limited to 15 or 20 minutes per day to avoid skin damage that can lead to skin cancer. Any unusual or bleeding moles should be checked by a dermatologist.
- Vaccinate against HPV. Infections by Human papillomaviruses (HPVs) are the primary cause of cervical cancer. There are more than 100 types of HPVs, but only a few pose a high risk of causing cancer. In 2006, the U.S. Food and Drug Administration approved Gardasil, a vaccine that is effective in preventing infection by the HPVs that cause most cervical cancers. Since HPV infections are very common and may not display any symptoms, vaccination for girls at an early age is recommended. This is something that parents should do for their daughters before they become sexually active.
- Avoid exposure to solvents. Gasoline, turpentine, dry cleaning fluid, and other solvents contain substances that are harmful when inhaled or when absorbed through the skin. Benzene is one of the harmful chemicals in gasoline. Long-term exposure to benzene affects the bone marrow where red blood cells form and eventually can cause leukemia. Do not breathe gasoline vapors or other solvents like nail polish remover, and do not expose your skin to chemical solvents that can be abosorbed through the skin.
- Eat vegetables and fruits. Colorectal cancer is associated with diets high in fat and low in fiber. Eat a diet with several servings of vegetables, fruits and whole grains a day for fiber, and eat lean cuts of meat. Compounds found in cruciferous vegetables, such as broccoli, cauliflower, and watercress, have been shown to block lung cancer progression in both animal studies and in tests with human lung cancer cells. The American Institute of Cancer Research estimates that by increasing the daily intake of fruits and vegetables to 5 servings per day, cancer rates could decline as much as 20%.
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