How Can Cancer Be Diagnosed?

Laboratory tests

If your physician suspects cancer during physical examination or while taking a medical history, they may order certain cancer blood tests to guide the diagnosis. Blood tests usually don’t detect cancer or benign tumors. However, blood tests can give a general idea about the functioning of your organs and if they have been affected by cancer. 

High or low levels of certain components in your blood could be a sign of cancer. Lab tests for blood, urine or other body fluids that measure these components can help your doctor identify cancer. Some of these lab tests include:

• Complete blood count (CBC) (high cell count)
• Urinalysis (presence of blood or transitional cells in urine)
• Tumor markers

Abnormal lab results do not always mean cancer.

Imaging tests

Imaging tests take images of body structures and organs. Imaging can help diagnose cancer by:

• Detecting tumors and other abnormalities.
• Determining the extent of the disease.
• Evaluate the effectiveness of treatment.

Some imaging tests include:

• Ultrasound: Uses high-energy sound waves that echo tissues in the body to create pictures of the organs and structures. An ultrasound, especially a Doppler ultrasound, is often used to diagnose cancer of the testis.
• Computed tomography (CT) scan: Uses an X-ray machine linked to the computer to create three-dimensional (3-D) images of the organs and structure of the body. A CT is often sensitive for cancer diagnosis of internal organs, such as lungs, ovaries and kidneys.
• Magnetic resonance imaging (MRI) scan: Uses a powerful magnet or radio waves to create images of the body in slices. These slices are used to create detailed images of the organs and structure, which helps differentiate healthy and unhealthy tissues. An MRI can often successfully detect the tumors of the brain, bone and heart.
• Nuclear scan: Uses radioactive material to create images of the organs and structures. Cancers in the active tissues, such as the thyroid, are often identified in this scan.
• Bone scan: A type of nuclear scan that identifies abnormal areas in bone. A bone scan can detect advanced cancer that has spread to the bones.
• Positron emission tomography (PET) scan: A type of nuclear scan that creates 3-D images of the area inside the body where glucose is absorbed.
• X-ray: Uses a low dose of radiation to create images of the organs and structures in the body. Cancers of bone are identified effectively by X-ray imaging.

Tumor biopsy

A biopsy is a diagnostic procedure to confirm whether the tissue is malignant or benign. In a tumor biopsy, the physician removes tissues or cells from the body for examination under a microscope. 

The most common types of biopsies include:

• Endoscopic biopsy
• Bone marrow biopsy
• Excisional or incisional biopsy
• Fine needle aspiration biopsy
• Punch biopsy
• Shave biopsy
• Skin biopsy

Endoscopic examination

The most commonly used endoscopic examination includes:

• Cystoscopy (also called cystourethroscopy): Examines the inside of the bladder.
• Colonoscopy: Examines the entire length of the colon and large intestine.
• Endoscopic retrograde cholangiopancreatography (ERCP): Examines the pancreas and biliary tree
• Esophagogastroduodenoscopy (also called EGD or upper endoscopy): Examines the esophagus, stomach and top of the small intestine.
• Sigmoidoscopy: Examine the lower part of the large intestine.

Genetic testing

Testing for mutations in genes that increases the risk of cancer is important for better management of cancer. These tests are highly specialized. They test for the mutations in genes: BRCA 1 and BRCA 2, MEN 1 and RET, APC, etc.