Cancer is a group of more than 100 different diseases. Cancer occurs when cells become abnormal and keep dividing and forming more cells without control or order.
All organs of the body are made of cells. Normally, cells divide to produce more cells only when the body needs them. This orderly process helps keeps us healthy.
If cells keep dividing when new cells are not needed, a mass of tissue forms. This mass of extra tissue, called a growth or tumor, can be benign or malignant.
- Benign tumors are not cancer. They can usually be removed and, in most cases, they do not come back. Most important, cells from benign tumors do not spread to other parts of the body. Benign tumors are rarely a threat to life.
- Malignant tumors are cancer. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. This is how cancer spreads from the original (primary) tumor to form new tumors in other parts of the body. The spread of cancer is called metastasis.
Most cancers are named for the type of cell or the organ in which they begin. When cancer spreads, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if lung cancer spreads to the liver, the cancer cells in the liver are lung cancer cells. The disease is called metastatic lung cancer (it is not liver cancer).
Screening and Early Detection
Sometimes, cancer can be found before the disease causes symptoms. Checking for cancer (or for conditions that may lead to cancer) in a person who does not have any symptoms of the disease is called screening.
Screening may involve a physical exam, lab tests, and/or procedures to look at internal organs, either directly or indirectly. During a physical exam, the doctor looks for anything unusual and feels for any lumps or growths. Examples of lab tests include blood and urine tests, the Pap test (microscopic examination of cells collected from the cervix), and the fecal occult blood test (to check for hidden blood in stool). Internal organs can be seen directly through a thin lighted tube (such as a sigmoidoscope, which lets the doctor see the rectum and the lower part of the colon) or indirectly with x-ray images (such as mammograms to check the breasts).
Doctors consider many factors before recommending a screening test. They weigh factors related to the individual, the test, and the cancer that the test is intended to detect. For example, doctors take into account the person’s age, medical history and general health, family history, and lifestyle. In addition, they assess the accuracy and the risks of the screening test and any followup tests that may be necessary. Doctors also consider the effectiveness and side effects of the treatment that will be needed if cancer is found. People may want to discuss any concerns or questions they have with their doctors, so they can weigh the pros and cons and make an informed decision about whether to have a screening test.
Symptoms of Cancer
You should see your doctor for regular checkups and not wait for problems to occur. But you should also know that the following symptoms may be associated with cancer: changes in bowel or bladder habits, a sore that does not heal, unusual bleeding or discharge, thickening or lump in the breast or any other part of the body, indigestion or difficulty swallowing, obvious change in a wart or mole, or nagging cough or hoarseness. These symptoms are not always a sign of cancer. They can also be caused by less serious conditions. Only a doctor can make a diagnosis. It is important to see a doctor if you have any of these symptoms. Don’t wait to feel pain: Early cancer usually does not cause pain.
If you have a sign or symptom that might mean cancer, the doctor will do a physical exam and ask about your medical history. In addition, the doctor usually orders various tests and exams. These may include imaging procedures, which produce pictures of areas inside the body; endoscopy, which allows the doctor to look directly inside certain organs; and laboratory tests. In most cases, the doctor also orders a biopsy, a procedure in which a sample of tissue is removed. A pathologist examines the tissue under a microscope to check for cancer cells.
Cancer is treated with surgery, radiation therapy, chemotherapy, hormone therapy, or biological therapy. Patients with cancer are often treated by a team of specialists, which may include a medical oncologist (specialist in cancer treatment), a surgeon, a radiation oncologist (specialist in radiation therapy), and others. The doctors may decide to use one treatment method or a combination of methods. The choice of treatment depends on the type and location of the cancer, the stage of the disease, the patient’s age and general health, and other factors.
Some cancer patients take part in a clinical trial (research study) using new treatment methods. Such studies are designed to improve cancer treatment. (Additional information can be found in the Clinical Trials section.)
Methods of Treatment
Surgery–Surgery is local therapy to remove the tumor. Tissues around the tumor and nearby lymph nodes may also be removed during the operation.
Radiation Therapy–In radiation therapy (also called radiotherapy), high-energy rays are used to damage cancer cells and stop them from growing and dividing. Like surgery, radiation therapy is local therapy; it can affect cancer cells only in the treated area.
Chemotherapy–Treatment with drugs to kill cancer cells is called chemotherapy. Most anticancer drugs are injected into a vein (IV) or a muscle; some are given by mouth. Chemotherapy is systemic treatment, meaning that the drugs flow through the bloodstream to nearly every part of the body.
Hormone Therapy–Some types of cancer, including most breast and prostate cancers, depend on hormones to grow. For this reason, doctors may recommend therapy that prevents cancer cells from getting or using the hormones they need. Sometimes, the patient has surgery to remove organs (such as the ovaries or testicles) that make the hormones; in other cases, the doctor uses drugs to stop hormone production or change the way hormones work. Like chemotherapy, hormone therapy is systemic treatment; it affects cells throughout the body.
Biological Therapy–Biological therapy (also called immunotherapy) is a form of treatment that uses the body’s natural ability (immune system) to fight infection and disease or to protect the body from some of the side effects of treatment. Monoclonal antibodies, interferon, interleukin-2 (IL-2), and several types of colony-stimulating factors (CSF, GM-CSF, G-CSF) are forms of biological therapy.
Nutrition for Cancer Patients
Some patients lose their appetite and find it hard to eat well. In addition, the common side effects of treatment, such as nausea, vomiting, or mouth sores, can make it difficult to eat. For some patients, foods taste different. Also, people may not feel like eating when they are uncomfortable or tired.
Eating well means getting enough calories and protein to help prevent weight loss and regain strength. Patients who eat well during cancer treatment often feel better and have more energy. In addition, they may be better able to handle the side effects of treatment.
Doctors, nurses, and dietitians can offer advice for healthy eating during cancer treatment. Patients and their families also may want to read the National Cancer Institute booklet Eating Hints for Cancer Patients, which contains many useful suggestions.
Causes and Prevention of Cancer
The number of new cases of cancer in the United States is going up each year. People of all ages get cancer, but nearly all types are more common in middle-aged and elderly people than in young people. Skin cancer is the most common type of cancer for both men and women. The next most common type among men is prostate cancer; among women, it is breast cancer. Lung cancer, however, is the leading cause of death from cancer for both men and women in the United States. Brain cancer and leukemia are the most common cancers in children and young adults.
These are some of the factors that are known to increase the risk of cancer:
- Tobacco – Tobacco causes cancer. In fact, smoking tobacco, using “smokeless” tobacco, and being regularly exposed to environmental tobacco smoke without smoking are responsible for one-third of all cancer deaths in the United States each year. Tobacco use is the most preventable cause of death in this country.Smoking accounts for more than 85 percent of all lung cancer deaths.
- Diet – Your choice of foods may affect your chance of developing cancer. Evidence points to a link between a high-fat diet and certain cancers, such as cancer of the breast, colon, uterus, and prostate. Being seriously overweight appears to be linked to increased rates of cancer of the prostate, pancreas, uterus, colon, and ovary, and to breast cancer in older women. On the other hand, studies suggest that foods containing fiber and certain nutrients help protect us against some types of cancer.
- Sunlight – Ultraviolet radiation from the sun and from other sources (such as sunlamps and tanning booths) damages the skin and can cause skin cancer. (Two types of ultraviolet radiation–UVA and UVB–are explained in the Medical Terms section.) Repeated exposure to ultraviolet radiation increases the risk of skin cancer, especially if you have fair skin or freckle easily. The sun’s ultraviolet rays are strongest during the summer from about 11 a.m. to about 3 p.m. (daylight saving time).
- Alcohol – Drinking large amounts of alcohol increases the risk of cancer of the mouth, throat, esophagus, and larynx. (People who smoke cigarettes and drink alcohol have an especially high risk of getting these cancers.) Alcohol can damage the liver and increase the risk of liver cancer. Some studies suggest that drinking alcohol also increases the risk of breast cancer. So if you drink at all, do so in moderation–not more than one or two drinks a day.
- Radiation – X-rays used for diagnosis expose you to very little radiation and the benefits nearly always outweigh the risks. However, repeated exposure can be harmful, so it is a good idea to talk with your doctor or dentist about the need for each x-ray and ask about the use of shields to protect other parts of your body.Before 1950, x-rays were used to treat noncancerous conditions (such as an enlarged thymus, enlarged tonsils and adenoids, ringworm of the scalp, and acne) in children and young adults.
- Chemicals – Chemicals and other substances in the workplace. Being exposed to substances such as metals, dust, chemicals, or pesticides at work can increase the risk of cancer. Asbestos, nickel, cadmium, uranium, radon, vinyl chloride, benzidene, and benzene are well-known examples of carcinogens in the workplace. These may act alone or along with another carcinogen, such as cigarette smoke.
- Hormone replacement therapy – Many women use estrogen therapy to control the hot flashes, vaginal dryness, and osteoporosis (thinning of the bones) that may occur during menopause. However, studies show that estrogen use increases the risk of cancer of the uterus. Other studies suggest an increased risk of breast cancer among women who have used high doses of estrogen or have used estrogen for a long time. At the same time, taking estrogen may reduce the risk of heart disease and osteoporosis.The risk of uterine cancer appears to be less when progesterone is used with estrogen than when estrogen is used alone. But some scientists are concerned that the addition of progesterone may also increase the risk of breast cancer.
Natural Treatments and Prevention
Some doctors recommend these nutrients, in a range of amounts, as part of a program to prevent or treat cancer.
Nutrients, Daily Amounts, and Applications
Beta-carotene: 10,000 – 25,000 international units
Folic acid: 400 – 800 micrograms
Selenium: 50 – 200 micrograms (l-selenomethionine)
Vitamin C: 250 -1,000 milligrams
Vitamin E: 400 – 600 international units
Check out these quality dietary supplements:
This program is used by the Cancer Treatment Centers of America, a national health care organization headquartered in Arlington Heights, Illinois, dedicated exclusively to the treatment of cancer. The centers combine nutritional, psychological and pastoral programs with traditional and innovative therapies in developing comprehensive, individualized treatment regimens for their patients.
If you have cancer, you should be under a doctor’s care. The high doses of vitamins and minerals recommended here should be taken only under knowledgeable medical supervision and are not substitutes for standard cancer treatment.
Talk to your doctor before taking more than 400 micrograms of folic acid daily, as high doses of this vitamin can mask symptoms of pernicious anemia, a vitamin B12-deficiency disease.
Selenium supplements in excess of 100 micrograms should be taken only under medical supervision.
Start with a low dose of vitamin C and work up to the higher amount. Large doses can cause diarrhea in some people.
If you are taking anticoagulant drugs, you should not take vitamin E supplements.