What Is Cancer?
"Cancer" is a group of more than 100 diseases. Different types of cancers have different causes. They differ in how easily they are treated, and in how they may be prevented.
All organs of the body are made up of cells. Normally, cells divide to produce more cells
only when the body needs them. This orderly process keeps us healthy. Cancer occurs when cells become
abnormal and keep dividing and forming more cells without control or order.
If the cells keep dividing when new cells are not needed, a mass of tissues forms. This mass of extra tissue is called a "growth" or "tumor." It can be "benign," or relatively harmless; or it may be "malignant" – meaning cancerous and dangerous.
What is the difference between benign and malignant tumors?
- Benign tumors are not really cancer. They can usually be removed and, in most cases, they do not return. Most importantly, cells from benign tumors do not spread to other parts of the body. Benign tumors are not usually life threatening.
- Malignant tumors are cancer. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from malignant tumors and spread to form new tumors in other parts of the body. The spread of cancer to other organs in the body is called "metastasis."
The cancer process begins long before symptoms appear or a diagnosis is made. The period of time that the cancer is hidden is called the "latent period." The latent period is usually in a range from 10 to 30 years. The long latent period makes it difficult to study the causes of cancer. People who get cancer today in Delaware may have been living in another state or country decades ago when the cancer began. Or, conditions in Delaware that caused someone's cancer 30 years ago may no longer be present.
Knowing the difference between incidence rates and death rates is important to understanding how much cancer is occurring and why.
- Incidence measures how often cancer occurs over a period of time. Think of it as
the number of people who are diagnosed with a disease in a year. Incidence is the best measure of the
risk of getting cancer. The incidence goes up if:
- more people develop cancer because they are exposed to a carcinogen (cause of cancer),
- doctors become better at finding the cancer, even if the number of cases hasn't really changed,
- procedures for reporting cancer improve.
- The death rate measures how often people die of cancer during a period of time. Death
rates may go up if:
- the incidence of cancer increases,
- the cancer is hard to treat,
- the cancer is undiagnosed or is found at an advanced stage when treatment is less effective,
- treatment is unavailable for a variety of reasons, including cost.
Reducing cancer in Delaware will depend on both preventing it and providing early and high quality treatment:
- Prevention – reducing risks of getting cancer by promoting healthier habits (such as not smoking and healthy eating) and reducing exposure to known carcinogens in the environment, home and worksite.
- Early Identification and Treatment – When cancer is diagnosed early, treatment is far more likely to be effective. It is important to follow recommended schedules for a variety of cancer screening tests recommended by your doctor. Appropriate follow-up and high quality care are also essential to lower the death rate and improve the quality of life for people with cancer.
What Causes Cancer?
We do not fully understand all the causes of cancer. We know the causes are a complex mix of heredity, lifestyle and environmental factors. Different types of cancers have different causes. Many causes of cancer – the best example is tobacco use – can be avoided. Other cancers are almost always caused by inherited traits and probably are not avoidable. Some causes of cancer are man-made and others are natural.
The risk of getting cancer increases as more "risk factors" are present. A person's chance of getting cancer depends, in large part, on how often the person is exposed to risk factors. It also depends on general health, age, and family history.
Some of the major known risk factors for cancer are:
Tobacco Use
Smoking tobacco, or using other tobacco products, and regular exposure to tobacco smoke are known to cause several types of cancer. Smoking causes between 85% and 90% of all lung cancer.
Diet
There is a link between a high-fat diet and cancer of the colon, uterus and prostate. Some studies indicate there may also be a link to breast cancer. Being overweight or obese is also linked to several types of cancer. On the other hand, eating a healthy diet — which includes five to nine servings of fruits and vegetables a day, as well as high-fiber whole-grain products – can help protect you against some types of cancer.
Sunlight
Ultraviolet radiation from the sun, and also from sun lamps and tanning beds, damages the skin and can cause skin cancer.
Alcohol Abuse
Drinking large amounts of alcoholic beverages increases the risk of cancer of the breast, mouth, throat, esophagus and larynx. These risks increase even more if the person also smokes.
Chemical Exposure In Your Environment
Being exposed to metals, chemicals or pesticides in your workplace or home environment can increase the risk of cancer. Asbestos, nickel, cadmium, uranium, radon, vinyl chloride, benzidene and benzene are all well known examples of carcinogens in the workplace.
Radiation
Too much exposure to some kinds of radiation can increase risk of cancer. To reduce chances of cancer, medical and dental X rays are adjusted to deliver the lowest dose of radiation possible. Too much radon exposure in homes may increase the risk of lung cancer, especially in smokers.
Viruses
Some cancers, especially cervical cancer in women, are caused by viruses. While the viruses that can lead to cancer are transmitted from one person to another, the cancer itself is not contagious. Cancer does not always occur when the virus is transmitted, and only a few viruses are known to cause cancer.
What Can We Do To Lower Cancer Rates?
Most cancer can be prevented or cured. The American Cancer Society and the Delaware Division of Public Health recommend the following actions to help prevent cancer:
- Don't start smoking; or quit if you're a current smoker.
- Maintain a desirable weight.
- Eat a varied diet low in animal fat, and high in fruits, vegetables and other complex carbohydrates (whole-grain products) and fiber.
- If you drink alcohol, drink in moderation.
- Eat less salt-cured, smoked and nitrite-cured foods.
- Avoid unnecessary exposure to the sun. When you're out in the sun, wear a hat, sunglasses and protective clothing; and use an effective sunblock (rated SPF 15 or higher)
- Check with health officials about the need to test your home for radon.
- Know what chemicals you work with at home or on your job; and learn what measures you can take to protect yourself.
- Women 40 and older should get a mammogram and clinical breast exam every year. All adult women should perform a monthly breast self-exam.
- All women who are sexually active and/or who are 18 or older should have annual Pap test and pelvic exam. After three or more normal exams, the doctor may decide the Pap test can be done less frequently. Follow your doctor's recommendations.
- Everyone 50 and older should have a colonoscopy or sigmoidoscopy, and it should be repeated every 3 to 5 years as recommended by your doctor. With any symptoms, such as blood in the stool, see your doctor and have a blood stool test.
- After age 50, men should discuss the possibility of a Prostate Specific Antigen (PSA) test with their doctor.
Public policies also should address issues such as environmental contamination, tobacco use, public education and access to screening and health care.
Information in this fact sheet is excerpted from the booklet, Cancer: What We Know and What We Don't Know, a publication of the Advisory Council for Cancer Control, Delaware Health and Social Services, published in March 2001.
