Cancer is suspected based on a person's symptoms, the results of a physical examination, abnormalities on laboratory studies done for other reasons, and sometimes the results of screening tests. Occasionally, x-ray studies done for other reasons, such as an injury, show abnormalities that might be cancer. Confirmation that cancer is present requires other tests (termed diagnostic tests).
After cancer is diagnosed, it is staged. Staging is a way of describing how advanced the cancer has become, including such criteria as how big it is and whether it has spread to neighboring tissues or more distantly to lymph nodes or other organs.
Imaging tests
Usually, when a doctor first suspects cancer, some type of imaging study, such as x-ray studies, ultrasound scans, or computed tomography scans (CT), is done. For example, a person with chronic cough and weight loss might have a chest x-ray study. A person with recurrent headaches and trouble seeing might have brain CT or magnetic resonance imaging (MRI) scanning. Although these tests can show the presence, location, and size of an abnormal mass, they cannot confirm that cancer is the cause.
Biopsy
Cancer is confirmed by obtaining a piece of the tumor through needle biopsy or surgery and finding cancer cells on microscopic examination of samples from the suspected area. Usually, the sample must be a piece of tissue, although sometimes examination of the blood is adequate (such as in leukemia). Obtaining a tissue sample is termed a biopsy.
Biopsies can be done by cutting out a small piece of tissue with a scalpel, but very commonly the sample is obtained using a hollow needle. Such tests are commonly done without the need for an overnight hospital stay (outpatient procedure). Doctors often use ultrasound or CT scanning to guide the needle to the right location. Because biopsies can be painful, the person is usually given a local anesthetic to numb the area.
Cancer biomarkers (also called tumor markers)
When examination findings or imaging test results suggest cancer, measuring blood levels of cancer biomarkers (substances secreted into the bloodstream by certain tumors) may provide additional evidence for or against the diagnosis of cancer. In people who have been diagnosed with certain types of cancer, cancer biomarkers may be useful to monitor the effectiveness of treatment and to detect possible recurrence of the cancer. For some cancers, the level of a cancer biomarker drops after treatment and increases if the cancer recurs.
Some cancer biomarkers cannot be measured in the blood but instead can be found on tumor cells. These biomarkers are found by examining tissue from a biopsy sample. HER2 and EGFR are examples of tumor markers found on tumor cells.
Some Cancer Biomarkers*
Cancer Biomarker | Description | Comment About Testing |
|---|---|---|
Alpha-fetoprotein (AFP) | Elevated AFP levels often are found in the blood of people with liver cancer (hepatocellular carcinoma). In addition, elevated AFP is often found in people with certain cancers of the ovary or testis. | Testing can be useful in monitoring treatment and perhaps for diagnosis of cancer in a person with cirrhosis (liver damage due to alcohol or viral hepatitis). |
Beta-human chorionic gonadotropin (ß-HCG) | This hormone is produced during pregnancy but also occurs in women who have a cancer originating in the placenta and in men with testicular cancer. | Testing can be useful in diagnosing such cancers and in monitoring treatment. |
Beta2 (ß2)-microglobulin | Levels may be elevated in people with multiple myeloma and some lymphomas. | This test is not recommended for cancer screening but is useful for monitoring the response to treatment. |
Calcitonin | Calcitonin is produced by certain cells in the thyroid gland (C cells). Blood levels are elevated in medullary thyroid cancer. | This test may be used to detect the presence of cancer and monitor response to treatment of medullary thyroid cancer. |
Carbohydrate antigen 125 (CA-125) | Levels may be elevated in women with a variety of gynecologic diseases, including ovarian cancer. | This test is not recommended for cancer screening but is useful for monitoring the response to treatment. |
Carbohydrate antigen 19-9 (CA 19-9) | Levels may be elevated in people with cancers of the digestive tract, particularly pancreatic cancer. | This test is used in monitoring response to treatment and in the diagnosis of tumors of unknown origin. |
Carbohydrate antigen 27.29 (CA27.29) | Levels may be elevated in people with breast cancer. | This test can be used in monitoring treatment. |
Carcinoembryonic antigen (CEA) | Levels may be elevated in the blood of people with colon cancer. Blood levels may also be elevated in people with other cancers or noncancerous inflammatory conditions. | After surgery for colon cancer, testing can be useful in monitoring treatment and detecting recurrence. |
Prostate-specific antigen (PSA) | Levels are elevated in men with noncancerous (benign) enlargement of the prostate and often are considerably higher in men with prostate cancer. Men with an elevated PSA level should be evaluated further by a doctor. | Testing may be useful in screening for cancer and is helpful in detecting recurrence after treatment. |
Thyroglobulin | Levels may be elevated in people with thyroid cancer or benign thyroid conditions. | This test is not recommended for routine screening but may be helpful for monitoring response to treatment of thyroid cancer. |
* Because cancer biomarkers can also be produced by noncancerous tissue, doctors generally do not use them to screen healthy people. Exceptions may include PSA for prostate cancer and AFP for people at risk of liver cancer. In families with inherited medullary thyroid cancer, a rare condition, levels of calcitonin in the blood also may be a useful screening test. | ||
Staging Cancer
After cancer is diagnosed, staging tests help determine how extensive the cancer is in terms of its location, size, growth into nearby structures, and spread to other parts of the body. People with cancer sometimes become impatient and anxious during staging tests, wishing for a prompt start of treatment. However, staging allows doctors to determine the most appropriate treatment as well as help to determine prognosis.
Staging may use scans or other imaging tests, such as x-rays, CT, MRI, bone scans with radioactive materials, or positron emission tomography (PET). The choice of staging test(s) depends on the type of cancer. CT scanning is used to detect cancer in many parts of the body, including the brain and lungs and parts of the abdomen, including the adrenal glands, lymph nodes, liver, and spleen. MRI is of particular value in detecting cancers of the brain, bones, and spinal cord.
Biopsies are often needed to confirm the presence of tumor for staging purposes and can sometimes be done together with the initial surgical treatment of a cancer. For example, during a laparotomy (an abdominal operation) to remove colon cancer, a surgeon removes nearby lymph nodes to check for spread of the cancer. During surgery for breast cancer, the surgeon biopsies or removes a lymph node located in the armpit (the first lymph nodes to which cancer is likely to spread, also called a sentinel lymph node) to determine whether the breast cancer has spread there. Evidence of spread, along with features of the primary tumor, helps the doctor determine whether further treatment is needed.
When staging is based only on initial biopsy results, physical examination, and imaging, the stage is referred to as clinical. When the doctor uses results of a surgical procedure or additional biopsies, the stage is referred to as pathologic or surgical. The clinical and pathologic (surgical) stages may differ.
In addition to imaging tests, doctors often obtain blood tests to see if the cancer has begun to affect the liver, bones, or kidneys.
Grading Cancer
Grading is a measure of how quickly the cancer is growing or spreading (called aggressiveness). A cancer's grade can help doctors determine prognosis. Grade is determined by examining the tissue specimen obtained during a biopsy. Grade is based on the degree of abnormality of the appearance of cancer cells on microscopic examination. More abnormal appearing cells are more aggressive. For many cancers, grading scales have been developed.
