Put simply, cancer is the abnormal growth of cells. Cancers arise from an organ or body structure and are composed of tiny cells that have lost the ability to stop growing. This growing mass of cells then projects from that organ or body structure until it becomes large enough to be noticed by a patient or physician. Occasionally, cancer may be detected "incidentally" by a laboratory test or x-ray - that is, the test or x-ray may have been ordered for purposes of routine screening or for an entirely different reason; in such a case, the cancer gets noticed almost by accident. at this point, it may be referred to as a "mass", "growth", "tumor", "nodule", "spot", "lump", "lesion", or "malignancy."
In general, the cancer must reach a size of 1 centimeter (that is, between 1/3 and 1/2 inch), or be made up of 1 million cells, before it is detected. Exceptions to this general rule include cancers of the blood and bone marrow - called lymphomas, leukemias, and multiple myeloma - which frequently do not produce a mass but will be evident on laboratory tests; these cancers still require more than a million cells to be present before they are detected. Lymphomas and Leukemias are examples of "liquid tumors," or cancers present in body fluids (the blood and bone marrow), and are detectable by laboratory tests of the blood. "Solid tumors" including cancers of the lung, breast, prostate, colon, rectum, and bladder - are not present in large enough numbers in body fluids to be detected with a blood test. However, they may release chemicals that are detectable in body fluids. A person with prostate cancer, for example, may have an elevated level of prostate - specific antigen, or PSA, in the blood-stream.
In general, the cancer must reach a size of 1 centimeter (that is, between 1/3 and 1/2 inch), or be made up of 1 million cells, before it is detected. Exceptions to this general rule include cancers of the blood and bone marrow - called lymphomas, leukemias, and multiple myeloma - which frequently do not produce a mass but will be evident on laboratory tests; these cancers still require more than a million cells to be present before they are detected. Lymphomas and Leukemias are examples of "liquid tumors," or cancers present in body fluids (the blood and bone marrow), and are detectable by laboratory tests of the blood. "Solid tumors" including cancers of the lung, breast, prostate, colon, rectum, and bladder - are not present in large enough numbers in body fluids to be detected with a blood test. However, they may release chemicals that are detectable in body fluids. A person with prostate cancer, for example, may have an elevated level of prostate - specific antigen, or PSA, in the blood-stream.
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