Tests and diagnosisBy Mayo Clinic staff
CLICK TO ENLARGE
|What does cancer look like?|
Diagnosing cancer at its earliest stages often provides the best chance for a cure. With this in mind, talk with your doctor about what types of cancer screening may be appropriate for you.
For a few cancers, studies show screening tests can save lives by diagnosing cancer early. For other cancers, screening tests are recommended only for people with the highest risk. Some cancer screening tests are controversial because there's no proof they save lives. In these cases, there is concern that tests may harm you or lead to treatment with no clear benefit or gain in life expectancy.
A variety of medical organizations and patient-advocacy groups have recommendations and guidelines for cancer screening. You and your doctor can review the various guidelines and determine what's best for you based on your own risk factors for cancer.
Your doctor may use one or more approaches to diagnose cancer:
- Physical exam. Your doctor may feel areas of your body for lumps that may indicate a tumor. During a physical exam he or she may look for abnormalities, such as changes in skin color or enlargement of an organ, that may indicate the presence of cancer.
- Laboratory tests. Laboratory tests, such as urine and blood tests, may help your doctor identify abnormalities that can be caused by cancer. For instance, in people with leukemia, a common blood test called complete blood count (CBC) may reveal an unusual number of white blood cells.
- Imaging tests. Imaging tests allow your doctor to examine your bones and internal organs in a noninvasive way. Imaging tests used in diagnosing cancer may include computerized tomography (CT) scan, bone scan, magnetic resonance imaging (MRI), ultrasound and X-ray, among others.
- Biopsy. During a biopsy, your doctor collects a sample of cells for testing in the laboratory. There are several ways of collecting a sample. Which biopsy procedure is right for you depends on your type of cancer and its location. In most cases, a biopsy is the only way to definitively diagnose cancer. In the laboratory, doctors look at cell samples under the microscope. Normal cells look uniform, with similar sizes and orderly organization. Cancer cells look less orderly, with varying sizes and without apparent organization.
Once cancer is diagnosed, your doctor will work to determine the extent (stage) of your cancer. Your doctor uses your cancer's stage to determine your treatment options and your chances for a cure. Staging tests and procedures may include imaging tests, such as bone scans or X-rays, to see if cancer has spread to other parts of the body.
Cancer stages are generally indicated by Roman numerals — I through IV, with higher numerals indicating more advanced cancer. In some cases, cancer stage is indicated using letters or words.
- Deaths and mortality. Centers for Disease Control and Prevention. http://www.cdc.gov/nchs/fastats/deaths.htm. Accessed April 17, 2012.
- Cancer: All sites. Surveillance Epidemiology and End Results. http://seer.cancer.gov/statfacts/html/all.html. Accessed April 17, 2012.
- What you need to know about cancer. National Cancer Institute. http://www.cancer.gov/cancertopics/wyntk/cancer/allpages. Accessed April 17, 2012.
- Kleinsmith LJ, et al. Understanding cancer. National Cancer Institute. http://nci.nih.gov/cancertopics/understandingcancer/cancer. Accessed April 17, 2012.
- Abeloff MD, et al. Abeloff's Clinical Oncology. 4th ed. Philadelphia, Pa.: Churchill Livingstone Elsevier; 2008. http://www.mdconsult.com/das/book/body/208746819-4/0/1709/0.html. Accessed April 17, 2012.
- Ulcerative colitis. National Institute of Diabetes and Digestive and Kidney Diseases. http://digestive.niddk.nih.gov/ddiseases/pubs/colitis/index.htm. Accessed April 17, 2012.
- NINDS paraneoplastic syndromes information page. National Institute of Neurological Disorder and Stroke. http://www.ninds.nih.gov/disorders/paraneoplastic/paraneoplastic.htm. Accessed April 17, 2012.
- Deng GE, et al. Evidence-based clinical practice guidelines for integrative oncology: Complementary therapies and botanicals. Journal of the Society for Integrative Oncology. 2009;7:85.
- Kushi LH, et al. American Cancer Society guidelines on nutrition and physical activity for cancer prevention: Reducing the risk of cancer with healthy food choices and physical activity. CA: A Cancer Journal for Clinicians. 2012;62:30.