1. What Is Cancer?
   
2. Screening and Early Detection
   
3. Symptoms of Cancer
   
4. Diagnosis
   
5. Treatment
   
6. Side Effects of CancerTreatment
   

What Is Cancer?

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.

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.

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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.

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 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.

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.