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Cancer Facts 1.        What is cancer? Cancer is a group of many related diseases. All cancers begin in cells, the building  blocks that make up tissues. Cancer that arises from organs and solid tissues is  called a solid tumor. Cancer that begins in blood cells is called leukemia, multiple  myeloma, or lymphoma. Normally, cells grow and divide to form new cells as the body needs them. When  cells grow old and die, new cells take their place. Sometimes this orderly process  goes wrong. New cells form when the body does not need them, and old cells do  not die when they should. The extra cells form a mass of tissue, called a growth or tumor. Tumors can be  either benign (not cancerous) or malignant (cancerous). Benign tumors do not  spread to other parts of the body, and they are rarely a threat to life. Malignant tumors  can spread (metastasize) and may be life threatening.   2.        What is primary cancer? Cancer can begin in any organ or tissue of the body. The original tumor is called the  primary cancer or primary tumor. It is usually named for the part of the body or the  type of cell in which it begins.   3.        What is metastasis, and how does it happen? Metastasis means the spread of cancer. Cancer cells can break away from a  primary tumor and enter the bloodstream or lymphatic system (the system that  produces, stores, and carries the cells that fight infections). That is how cancer cells  spread to other parts of the body. When cancer cells spread and form a new tumor in a different organ, the new tumor   is a metastatic tumor. The cells in the metastatic tumor come from the original   tumor. This means, for example, that if breast cancer spreads to the lungs, the   metastatic tumor in the lung is made up of cancerous breast cells (not lung cells). In   this case, the disease in the lungs is metastatic breast cancer (not lung cancer).   Under a microscope, metastatic breast cancer cells generally look the same as the   cancer cells in the breast.   4.        Where does cancer spread? Cancer cells can spread to almost any part of the body. Cancer cells frequently  spread to lymph nodes (rounded masses of lymphatic tissue) near the primary  tumor (regional lymph nodes). This is called lymph node involvement or regional  disease. Cancer that spreads to other organs or to lymph nodes far from the primary  tumor is called metastatic disease. Doctors sometimes also call this distant  disease. The most common sites of metastasis from solid tumors are the lungs, bones, liver,  and brain. Some cancers tend to spread to certain parts of the body. For example,  lung cancer often metastasizes to the brain or bones, and colon cancer frequently  spreads to the liver. Prostate cancer tends to spread to the bones. Breast cancer  commonly spreads to the bones, lungs, liver, or brain. However, each of these  cancers can spread to other parts of the body as well. Because blood cells travel throughout the body, leukemia, multiple myeloma, and  lymphoma cells are usually not localized when the cancer is diagnosed. Tumor cells  may be found in the blood, several lymph nodes, or other parts of the body such as  the liver or bones. This type of spread is not referred to as metastasis.   5.        Are there symptoms of metastatic cancer? Some people with metastatic cancer do not have symptoms. Their metastases are  found by x-rays and other tests performed for other reasons. When symptoms of metastatic cancer occur, the type and frequency of the  symptoms will depend on the size and location of the metastasis. For example,  cancer that spreads to the bones is likely to cause pain and can lead to bone  fractures. Cancer that spreads to the brain can cause a variety of symptoms,  including headaches, seizures, and unsteadiness. Shortness of breath may be a  sign of lung involvement. Abdominal swelling or jaundice (yellowing of the skin) can  indicate that cancer has spread to the liver. Sometimes a person’s primary cancer is discovered only after the metastatic tumor  causes symptoms. For example, a man whose prostate cancer has spread to the  bones in his pelvis may have lower back pain (caused by the cancer in his bones)  before he experiences any symptoms from the primary tumor in his prostate.   6.        How does a doctor know whether a cancer is a primary or a metastatic   tumor? To determine whether a tumor is primary or metastatic, a pathologist examines a  sample of the tumor under a microscope. In general, cancer cells look like abnormal  versions of cells in the tissue where the cancer began. Using specialized diagnostic  tests, a pathologist is often able to tell where the cancer cells came from. Markers or  antigens found in or on the cancer cells can indicate the primary site of the cancer. Metastatic cancers may be found before or at the same time as the primary tumor, or  months or years later. When a new tumor is found in a patient who has been treated  for cancer in the past, it is more often a metastasis than another primary tumor.   7.        Is it possible to have a metastatic tumor without having a primary cancer? No. A metastatic tumor always starts from cancer cells in another part of the body. In   most cases, when a metastatic tumor is found first, the primary tumor can be found.   The search for the primary tumor may involve lab tests, x-rays, and other procedures.   However, in a small number of cases, a metastatic tumor is diagnosed but the   primary tumor cannot be found, in spite of extensive tests. The pathologist knows the   tumor is metastatic because the cells are not like those in the organ or tissue in   which the tumor is found. Doctors refer to the primary tumor as unknown or occult   (hidden), and the patient is said to have cancer of unknown primary origin (CUP).   Because diagnostic techniques are constantly improving, the number of cases of   CUP is going down. What treatments are used for metastatic cancer? When cancer has metastasized, it may be treated with chemotherapy, radiation  therapy, biological therapy, hormone therapy, surgery, cryosurgery, or a combination  of these. The choice of treatment generally depends on the type of primary cancer,  the size and location of the metastasis, the patient’s age and general health, and the  types of treatments the patient has had in the past. In patients with CUP, it is  possible to treat the disease even though the primary tumor has not been located.  The goal of treatment may be to control the cancer, or to relieve symptoms or side  effects of treatment.   8.        Are new treatments for metastatic cancer being developed? Yes, many new cancer treatments are under study. To develop new treatments, the  NCI sponsors clinical trials (research studies) with cancer patients in many  hospitals, universities, medical schools, and cancer centers around the country.  Clinical trials are a critical step in the improvement of treatment. Before any new  treatment can be recommended for general use, doctors conduct studies to find out  whether the treatment is both safe for patients and effective against the disease. The  results of such studies have led to progress not only in the treatment of cancer, but  in the detection, diagnosis, and prevention of the disease as well. Patients  interested in taking part in a clinical trial should talk with their doctor.

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