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. 

Diagnosis

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.

Imaging

Images of areas inside the body help the doctor tell whether a tumor is present. These images can be made in several ways. In many cases, the doctor uses a special dye so that certain organs show up better on film. The dye may be swallowed or put into the body through a needle or a tube.

X-rays are the most common way doctors make pictures of the inside of the body. In a special kind of x-ray imaging, a CT or CAT scan uses a computer linked to an x-ray machine to make a series of detailed pictures.

In radionuclide scanning, the patient swallows or is given an injection of a mildly radioactive substance. A machine (scanner) measures radioactivity levels in certain organs and prints a picture on paper or film. By looking at the amount of radioactivity in the organs, the doctor can find abnormal areas.

Ultrasonography is another procedure for viewing the inside of the body. High-frequency sound waves that cannot be heard by humans enter the body and bounce back. Their echoes produce a picture called a sonogram. These pictures are shown on a monitor like a TV screen and can be printed on paper.

In MRI, a powerful magnet linked to a computer is used to make detailed pictures of areas in the body. These pictures are viewed on a monitor and can also be printed.

Endoscopy

Endoscopy allows the doctor to look into the body through a thin, lighted tube called an endoscope. The exam is named for the organ involved (for example, colonoscopy to look inside the colon). During the exam, the doctor may collect tissue or cells for closer examination.

Laboratory Tests

Although no single test can be used to diagnose cancer, laboratory tests such as blood and urine tests give the doctor important information. If cancer is present, lab work may show the effects of the disease on the body. In some cases, special tests are used to measure the amount of certain substances in the blood, urine, other body fluids, or tumor tissue. The levels of these substances may become abnormal when certain kinds of cancer are present.

Biopsy

The physical exam, imaging, endoscopy, and lab tests can show that something abnormal is present, but a biopsy is the only sure way to know whether the problem is cancer. In a biopsy, the doctor removes a sample of tissue from the abnormal area or may remove the whole tumor. A pathologist examines the tissue under a microscope. If cancer is present, the pathologist can usually tell what kind of cancer it is and may be able to judge whether the cells are likely to grow slowly or quickly.

Staging

When cancer is found, the patient's doctor needs to know the stage, or extent, of the disease to plan the best treatment. The doctor may order various tests and exams to find out whether the cancer has spread and, if so, what parts of the body are affected. In some cases, lymph nodes near the tumor are removed and checked for cancer cells. If cancer cells are found in the lymph nodes, it may mean that the cancer has spread to other organs. 

Treatment

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.)

Getting a Second Opinion

Before starting treatment, the patient may want another doctor to review the diagnosis and treatment plan. Some insurance companies require a second opinion; others may pay for a second opinion if the patient requests it. There are a number of ways to find specialists to consult for a second opinion:

• The patient's doctor may suggest a specialist for a second opinion.
• The Cancer Information Service, at 1-800-4-CANCER, can tell callers about treatment facilities, including cancer centers and other programs in their area supported by the National Cancer Institute.
• Patients can get the names of doctors from their local medical society, a nearby hospital, or a medical school.

Preparing for Treatment

Many people with cancer want to learn all they can about their disease and their treatment choices so they can take an active part in decisions about their medical care. Often, it helps to make a list of questions to ask the doctor. Patients may take notes or, with the doctor's consent, tape record the discussion. Some patients also find it helps to have a family member or friend with them when they talk with the doctor--to take part in the discussion, to take notes, or just to listen.

Here are some questions a patient may want to ask the doctor:

• What is my diagnosis?
• What is the stage of the disease?
• What are my treatment choices? Which do you recommend for me? Why?
• What are the chances that the treatment will be successful?
• Would a clinical trial be appropriate for me?
• What are the risks and possible side effects of each treatment?
• How long will treatment last?
• Will I have to change my normal activities?
• What is the treatment likely to cost?

When a person is diagnosed with cancer, shock and stress are natural reactions. These feelings may make it difficult to think of every question to ask the doctor. Patients may find it hard to remember everything the doctor says. They should not feel they need to ask all their questions or remember all the answers at one time. They will have other chances for the doctor to explain things that are not clear and to ask for more information.

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. Radiation may come from a machine (external radiation). It also may come from an implant (a small container of radioactive material) placed directly into or near the tumor (internal radiation). Some patients get both kinds of radiation therapy.

External radiation therapy is usually given on an outpatient basis in a hospital or clinic 5 days a week for several weeks. Patients are not radioactive during or after the treatment.

For internal radiation therapy, the patient stays in the hospital for a few days. The implant may be temporary or permanent. Because the level of radiation is highest during the hospital stay, patients may not be able to have visitors or may have visitors only for a short time. Once an implant is removed, there is no radioactivity in the body. The amount of radiation in a permanent implant goes down to a safe level before the patient leaves the hospital.

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.

Often, patients who need many doses of IV chemotherapy receive the drugs through a catheter (a thin flexible tube). One end of the catheter is placed in a large vein in the chest. The other end is outside the body or attached to a small device just under the skin. Anticancer drugs are given through the catheter. This can make chemotherapy more comfortable for the patient. Patients and their families are shown how to care for the catheter and keep it clean. For some types of cancer, doctors are studying whether it helps to put anticancer drugs directly into the affected area.

Chemotherapy is generally given in cycles: A treatment period is followed by a recovery period, then another treatment period, and so on. Usually a patient has chemotherapy as an outpatient--at the hospital, at the doctor's office, or at home. However, depending on which drugs are given and the patient's general health, the patient may need to stay in the hospital for a short time.

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. 

Side Effects of Cancer Treatment

It is hard to limit the effects of treatment so that only cancer cells are removed or destroyed. Because treatment also damages healthy cells and tissues, it often causes unpleasant side effects.

The side effects of cancer treatment vary. They depend mainly on the type and extent of the treatment. Also, each person reacts differently. Doctors try to plan the patient's therapy to keep side effects to a minimum and they can help with any problems that occur.

Surgery--The side effects of surgery depend on the location of the tumor, the type of operation, the patient's general health, and other factors. Although patients are often uncomfortable during the first few days after surgery, this pain can be controlled with medicine. Patients should feel free to discuss pain relief with the doctor or nurse. It is also common for patients to feel tired or weak for a while. The length of time it takes to recover from an operation varies for each patient.

Radiation Therapy--With radiation therapy, the side effects depend on the treatment dose and the part of the body that is treated. The most common side effects are tiredness, skin reactions (such as a rash or redness) in the treated areas, and loss of appetite. Radiation therapy also may cause a decrease in the number of white blood cells, cells that help protect the body against infection. Although the side effects of radiation therapy can be unpleasant, the doctor can usually treat or control them. It also helps to know that, in most cases, they are not permanent.

Chemotherapy--The side effects of chemotherapy depend mainly on the drugs and the doses the patient receives. Generally, anticancer drugs affect cells that divide rapidly. These include blood cells, which fight infection, help the blood to clot, or carry oxygen to all parts of the body. When blood cells are affected by anticancer drugs, patients are more likely to get infections, may bruise or bleed easily, and may have less energy. Cells that line the digestive tract also divide rapidly. As a result of chemotherapy, patients may have side effects, such as loss of appetite, nausea and vomiting, hair loss, or mouth sores. For some patients, the doctor may prescribe medicine to help with side effects, especially with nausea and vomiting. Usually, these side effects gradually go away during the recovery period or after treatment stops.

Hair loss, another side effect of chemotherapy, is a major concern for many patients. Some chemotherapy drugs only cause the hair to thin out, while others may result in the loss of all body hair. Patients may feel better if they decide how to handle hair loss before starting treatment.

In some men and women, chemotherapy drugs cause changes that may result in a loss of fertility (the ability to have children). Loss of fertility may be temporary or permanent depending on the drugs used and the patient's age. For men, sperm banking before treatment may be a choice. Women's menstrual periods may stop, and they may have hot flashes and vaginal dryness. Periods are more likely to return in young women.

In some cases, bone marrow transplantation and peripheral stem cell support are used to replace tissue that forms blood cells when that tissue has been destroyed by the effects of chemotherapy or radiation therapy. (See more about these procedures in the Glossary.)

Hormone Therapy--Hormone therapy can cause a number of side effects. Patients may have nausea and vomiting, swelling or weight gain, and, in some cases, hot flashes. In women, hormone therapy also may cause interrupted menstrual periods, vaginal dryness, and, sometimes, loss of fertility. Hormone therapy in men may cause impotence, loss of sexual desire, or loss of fertility. These changes may be temporary, long lasting, or permanent.

Biological Therapy--The side effects of biological therapy depend on the type of treatment. Often, these treatments cause flu-like symptoms such as chills, fever, muscle aches, weakness, loss of appetite, nausea, vomiting, and diarrhea. Some patients get a rash, and some bleed or bruise easily. In addition, interleukin therapy can cause swelling. Depending on how severe these problems are, patients may need to stay in the hospital during treatment. These side effects are usually short-term; they gradually go away after treatment stops.

Doctors and nurses can explain the side effects of cancer treatment and help with any problems that occur. The National Cancer Institute booklets Radiation Therapy and You and Chemotherapy and You also have helpful information about cancer treatment and coping with side effects. 

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. 

Clinical Trials

When laboratory research shows that a new treatment method has promise, cancer patients can receive the treatment in carefully controlled trials. These trials are designed to find out whether the new approach is both safe and effective and to answer scientific questions. Often, clinical trials compare a new treatment with a standard approach so that doctors can learn which is more effective.

Researchers also look for ways to reduce the side effects of treatment and improve the quality of patients' lives. Patients who take part in clinical trials make an important contribution to medical science. These patients take certain risks, but they also may have the first chance to benefit from improved treatment methods.

Clinical trials offer important options for many patients. Cancer patients who are interested in taking part in a clinical trial should talk with their doctor. They may want to read Taking Part in Clinical Trials: What Cancer Patients Need To Know, a booklet that explains treatment studies and outlines some of their possible benefits and risks.

One way to learn about clinical trials is through PDQ, a computerized resource developed by the National Cancer Institute. PDQ contains information about cancer treatment and about clinical trials in progress all over the country. The Cancer Information Service can provide PDQ information to doctors, patients, and the public. 

Support for Cancer Patients

Living with a serious disease is difficult. Cancer patients and those who care about them face many problems and challenges. Coping with these problems is often easier when people have helpful information and support services.

Cancer patients may worry about holding their job, caring for their family, or keeping up daily activities. Worries about tests, treatments, hospital stays, and medical bills are also common. Doctors, nurses, and other members of the health care team can answer questions about treatment, working, or daily activities. Meeting with a social worker, counselor, or member of the clergy also can be helpful to patients who want to talk about their feelings or discuss their concerns about the future or about personal relationships.

Friends and relatives, especially those who have had personal experience with cancer, can be very supportive. Also, it helps many patients to meet with others who are facing problems like theirs. Cancer patients often get together in support groups, where they can share what they have learned about cancer and its treatment and about coping with the disease. It is important to keep in mind, however, that each patient is different. Treatments and ways of dealing with cancer that work for one person may not be right for another-- even if both have the same kind of cancer. It is always a good idea to discuss the advice of friends and family members with the doctor.

Often, a social worker at the hospital or clinic can suggest groups that help with rehabilitation, emotional support, financial aid, transportation, or home care. The American Cancer Society has many services for patients and families. Local offices of the American Cancer Society are listed in the white pages of the telephone directory.

In addition, the public library has many books and articles on living with cancer. The Cancer Information Service also has information on local resources. 

What the Future Holds

Researchers are finding better ways to detect and treat cancer, and the chance of recovery keeps improving. Still, it is natural for patients to be concerned about their future.

Sometimes patients use statistics to try to figure out their chance of being cured. It is important to remember, however, that statistics are averages based on large numbers of patients. They cannot be used to predict what will happen to a particular patient because no two patients are alike. The doctor who takes care of the patient is in the best position to discuss the chance of recovery (prognosis). Patients should feel free to ask the doctor about their prognosis, but they should keep in mind that not even the doctor knows exactly what will happen. Doctors often talk about surviving cancer, or they may use the term remission rather than cure. Even though many cancer patients are cured, doctors use these terms because the disease may recur. 

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.

The more we can learn about what causes cancer, the more likely we are to find ways to prevent it. Scientists study patterns of cancer in the population to look for factors that affect the risk of developing this disease. In the laboratory, they explore possible causes of cancer and try to determine what actually happens when normal cells become cancerous.

Our current understanding of the causes of cancer is incomplete, but it is clear that cancer is not caused by an injury, such as a bump or bruise. And although being infected with certain viruses may increase the risk of some types of cancer, cancer is not contagious; no one can "catch" cancer from another person.

Cancer develops gradually as a result of a complex mix of factors related to environment, lifestyle, and heredity. Scientists have identified many risk factors that increase the chance of getting cancer. They estimate that about 80 percent of all cancers are related to the use of tobacco products, to what we eat and drink, or, to a lesser extent, to exposure to radiation or cancer-causing agents (carcinogens) in the environment and the workplace. Some people are more sensitive than others to factors that can cause cancer.

Many risk factors can be avoided. Others, such as inherited risk factors, are unavoidable. It is helpful to be aware of them, but it is also important to keep in mind that not everyone with a particular risk factor for cancer actually gets the disease; in fact, most do not. People at risk can help protect themselves by avoiding risk factors where possible and by getting regular checkups so that, if cancer develops,