How Is Cancer Diagnosed?

There is no single test that can accurately diagnose cancer. The complete evaluation of a patient usually requires a thorough history and physical examination along with diagnostic testing. Many tests are needed to determine whether a person has cancer, or if another condition (such as an infection) is mimicking the symptoms of cancer.

Effective diagnostic testing is used to confirm or eliminate the presence of disease, monitor the disease process, and to plan for and evaluate the effectiveness of treatment. In some cases, it is necessary to repeat testing when a person's condition has changed, if a sample collected was not of good quality, or an abnormal test result needs to be confirmed.

Diagnostic procedures for cancer may include imaging, laboratory tests (including tests for tumor markers), tumor biopsy, endoscopic examination, surgery, or genetic testing.

Cancer diagnosis methods:

  • Lab tests
  • Diagnostic imaging
  • Endoscopic exams
  • Genetic tests
  • Tumor biopsies

What are the different types of lab tests used to diagnose cancer?

Clinical chemistry uses chemical processes to measure levels of chemical components in body fluids and tissues. The most common specimens used in clinical chemistry are blood and urine.

Many different tests exist to detect and measure almost any type of chemical component in blood or urine. Components may include blood glucose, electrolytes, enzymes, hormones, lipids (fats), other metabolic substances, and proteins.

The following are some of the more common laboratory tests:

Learn more about laboratory tests.

Diagnostic imaging

Diagnostic radiology has greatly advanced in recent years with the development of new instruments and techniques that can better detect cancer and also help patients avoid surgery.

The diagnostic radiology staff and physicians at the Stanford Cancer Center are leaders in their field and have access to the most advanced technology available today for imaging of cancer.

In fact, the expertise of our doctors is so well recognized that we proudly serve as a reference center, meaning that outside physicians can send our staff complex or borderline images and receive expert interpretation for their patients.

In addition to advanced instruments and experienced staff, the Cancer Center was designed to improve the delivery of diagnostic radiology. For example, we have consolidated imaging workstations for mammograms, ultrasounds, and magnetic resonance images in one room, allowing physicians to directly compare images from multiple sources.

This unprecedented cross-platform, simultaneous access ensures that all of the relevant data is at your doctor's fingertips when s/he is making important decisions about your care.

What are the different types of diagnostic imaging?

Imaging is the process of producing valuable pictures of body structures and organs. It is used to detect tumors and other abnormalities, to determine the extent of disease, and to evaluate the effectiveness of treatment. Imaging may also be used when performing biopsies and other surgical procedures. There are three types of imaging used for diagnosing cancer: transmission imaging, reflection imaging, and emission imaging. Each uses a different process.

Transmission imaging

X-rays, computed tomography scans (CT scans), and fluoroscopy are radiological examinations whose images are produced by transmission. In transmission imaging, a beam of high-energy photons is produced and passed through the body structure being examined. The beam passes very quickly through less dense types of tissue such as watery secretions, blood, and fat, leaving a darkened area on the X-ray film. Muscle and connective tissues (ligaments, tendons, and cartilage) appear gray. Bones will appear white.

Reflection imaging

Reflection imaging refers to the type of imaging produced by sending high-frequency sounds to the body part or organ being studied. These sound waves "bounce" off of the various types of body tissues and structures at varying speeds, depending on the density of the tissues present. The bounced sound waves are sent to a computer that analyzes the sound waves and produces a visual image of the body part or structure.

Emission imaging

Emission imaging occurs when tiny nuclear particles or magnetic energy are detected by a scanner and analyzed by computer to produce an image of the body structure or organ being examined. Nuclear medicine uses emission of nuclear particles from nuclear substances introduced into the body specifically for the examination. Magnetic resonance imaging (MRI) uses radio waves with a machine that creates a strong magnetic field that in turn causes cells to emit their own radio frequencies.

What are the different types of endoscopic examinations used to diagnose cancer?

Types of endoscopies include:

What are the different types of genetic testing used to diagnose cancer?

Testing for mutations in genes that give an increased risk for cancer is complicated. The concepts are important to understand when considering cancer susceptibility gene testing.

Learn more about:

What are the different types of tumor biopsies used to diagnose cancer?

A biopsy is a procedure performed to remove tissue or cells from the body for examination under a microscope. Some biopsies can be performed in a physician's office, while others need to be done in a hospital setting. In addition, some biopsies require use of an anesthetic to numb the area, while others do not require any sedation.

Biopsies are usually performed to determine whether a tumor is malignant (cancerous) or to determine the cause of an unexplained infection or inflammation. 

The following are the most common types of biopsies:

Clinical Trials

Clinical trials are research studies that evaluate a new medical approach, device, drug, or other treatment. As a Stanford Health Care patient, you may have access to the latest, advanced clinical trials.

Open trials refer to studies currently accepting participants. Closed trials are not currently enrolling, but may open in the future.

Before beginning treatment, ask your doctor about any clinical trials you should consider. Learn more about clinical trials for cancer patients.