What is Cancer?
Cancer is the general name for a group of more than 100 diseases in which cells in a part of the body begin to grow out of control. Although there are many kinds of cancer, they all start because abnormal cells grow out of control. Untreated cancers can cause serious illness and even death.
If your doctor suspects you have cancer, he or she will conduct tests to confirm that diagnosis. The type of cancer and its progress is assessed through an evaluative process known as cancer staging, using one or more diagnostic options.
First Steps to Diagnosis
If you're experiencing signs or symptoms that may indicate cancer, your doctor typically starts by asking about your medical history and giving you a physical exam. Medical information that your doctor may ask about includes detailed accounts of: your current health, including any current physical complaints; your past health, including prior medical conditions; your family's history of illness, including cancer; any environmental exposures that might have put you at risk of cancer. A physical exam allows your doctor to further evaluate your overall health. The doctor may examine your entire body or focus on areas of concern.
Blood and Urine Tests
If your medical history and physical exam suggest the need for further testing, your doctor may use blood and urine tests to help rule out or diagnose disease. Small amounts of blood and urine are collected and then, in a laboratory, are analyzed for abnormalities.
Diagnostic Imaging: Determining cancer location, size and spread
Diagnostic imaging tools, such as X-ray and magnetic resonance imaging (MRI), allow your doctor to create pictures of your bones, organs and other areas inside your body. These images can help your doctor determine whether you have a tumor, where in your body it's location, how large it is and if it has spread. Commonly used imaging techniques include:
X-rays take pictures of your bones and internal organs. X-rays are often used to examine cancers of the lungs, intestines, stomach, kidneys and breasts.
Computerized tomography (CT)
Computerized tomography is an X-ray technique that produces more-detailed images of your internal organs than those of conventional X-rays. CT scans can pinpoint a tumor or infection deep in the brain, abdomen or chest and are the best way to evaluate your lungs for evidence of tumor spread. CT scans are typically used to examine your brain, lungs, liver, pancreas, adrenal glands and bones.
Magnetic resonance imaging (MRI)
Like computerized tomography, MRI also gives you a detailed glimpse inside your body. But MRI uses an extremely strong magnet, rather than X-rays. In some cases, MRI can be more sensitive than CT. MRI is often used to detect cancer of the brain, spinal cord, head and neck, liver and soft tissues.
Ultrasound technology works by bouncing high-frequency sound waves off tissues in your body to form images on a small monitor that looks like a television screen. Ultrasound is helpful in diagnosing cancers found in soft tissues. For example, it can be used to help determine whether a mass found in your breast is a fluid-filled cyst or a solid tumor. It can also help doctors locate the tumor when they need to extract sample tissue for further study (biopsy).
Mammogram can detect a breast lump years before you can and that can save your life. Every woman should follow the American Cancer Society recommendation — yearly screening mammography beginning at age 40.
A biopsy — the removal of a sample of tissue for study, generally under a microscope — is always necessary to make a cancer diagnosis. Sample tissue may be removed by using techniques that commonly include:
Your doctor uses a thin needle and a syringe to remove small pieces of tissue from a tumor. Two types of needle biopsy exist — fine-needle aspiration and core biopsy. These procedures are essentially the same, but core biopsy involves using a slightly larger needle to remove a small, solid core of tissue. Any tissue can be biopsied, including the liver, lung, brain and bone marrow.
Your doctor inserts a thin, flexible tube (endoscope) into a natural opening in your body, such as your rectum or mouth and throat. The endoscope contains a fiber-optic light and a video camera at its tip. The camera lens transmits images to an external monitor so that your doctor can look closely at areas inside your body. If the doctor sees abnormal looking tissue, he or she can insert instruments through the endoscope to remove sample tissue.
The doctor makes an incision through the skin and removes either an entire tumor or a portion of a tumor. In some cases, only local anesthesia is needed; other times, such as when a tumor inside the chest, the doctor may use general anesthesia.
After your doctor obtains a tissue sample, it's generally chemically treated and sliced into very thin sections. These sections are placed on glass slides, stained — to enhance contrast — and studied under a microscope by a person who specializes in examining body tissues (pathologist) or a specialist in blood and blood-forming tissues (hematologist), or both. This allows your doctor to determine exactly where the cancer came from.
Biopsy also helps your doctor determine the cancer's grade — an assigned number on a scale of one to four that refers to the appearance of cancer cells under the microscope. Grade 1 cancers are generally the least aggressive and grade 4 cancers, the most aggressive. This information may help guide treatment options.
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