Diagnosing Cancer

How Do I Find Out if I Have Cancer?

If your family doctor suspects you have cancer, there are a number of diagnostic tests—ranging from noninvasive imaging to surgical biopsies—that can help them make an accurate diagnosis.

Diagnostic Imaging


Believe it or not, a simple X-ray can be the first step in diagnosing cancer. An experienced radiologist can often identify abnormal areas that may indicate the growth of abnormal cells.

CT and PET Scans

CT and PET scans are very similar procedures—for both, you will put on a hospital gown and lie down on a table that moves through a circular scanner that takes radiation-enhanced images of the inside of your body.

For a CT (computerized axial tomography) scan, generally, you’ll either drink and/or be injected with some form of contrast material (a special dye that highlights the area of the body being examined, from blood vessels to intestines).

A PET (positron emission tomography) scan works a little differently. Because cancer tissues are defined by their abnormal growth, a PET scan identifies any areas of the body where glucose is being metabolized faster than in other areas of the body. Depending on the area of your body being examined, you’ll either inhale, swallow or be injected with a radioactive tracer that lights up in areas of accelerated chemical activity.

MRI (Magnetic Resonance Imaging)

In an MRI, powerful magnets will create a detailed computer-generated cross-sections of your body’s soft tissue, blood vessels and major organs. An MRI generally provides higher-contrast images of the brain, spine, muscle, bone and connective tissue than CT scan can.

Unlike X-rays and CT and PET scans, an MRI does not expose the patient to radiation, but sometimes you will need to be injected with contrast solution to highlight certain areas.


This painless, noninvasive procedure enables doctors to determine whether a lump or swelling is filled with fluid or is solid. If the area is solid, then further testing will be needed.


Mammography is a specialized form of X-ray used to check for breast cancer in women. Multiple images of the breast are taken from a variety of angles to identify tumors that are too small to be felt or small deposits of calcium that can sometimes be related to breast cancer.


Endoscopy involves inserting a flexible plastic tube with a tiny camera at the end into body cavities such as the colon or the esophagus, or through tiny surgical openings to access the abdominal cavity. Endoscopy enables your doctor to view the inside of your body without putting you through the discomfort and risk of major surgery.

Blood Tests

Some cancers release specific substances (antigens) that stimulate an immune response from your body. Not all of these antigens have been identified yet, nor does the presence nor absence of a particular antigen guarantee that you either have or do not have a particular form of cancer. However, it is a relatively painless and inexpensive way for your doctor to begin diagnosing your cancer, or to monitor its progress as you go through treatment.

Complete Blood Count

Abnormal levels of white blood cells or platelets can be an indicator of leukemia. If you are experiencing symptoms of leukemia (fever or chills, fatigue, frequent infections, swollen lymph nodes, unusual bleeding, night sweets), your doctor will likely begin with a complete blood count.

PSA (Prostate Specific Antigen)

PSA is a protein produced by the prostate gland. The higher a man’s PSA level, the more likely it is that he has prostate cancer.


Elevated levels of Cancer Antigen 125 (CA-125) have been found in many women with ovarian cancer. While there are many noncancerous conditions that can increase CA-125 (including menstruation and uterine fibroids), it can be an early indicator of gynecological cancers including ovarian, endometrial, and fallopian tube cancers. However, it is not accurate enough to use as a screening tool for all women—there are many women with ovarian cancer who do not experience an increase in CA-125.


When a suspicious mass is identified through diagnostic imaging and/or laboratory testing, the next step is to get a sample of the tissue so that it can be examined under a microscope. Generally, samples are collected by using a local anesthetic to numb the area where cancer is suspected, then inserting a long, thin needle into the mass to collect cells. The placement of the needle is usually guided by various imaging tools, from ultrasound to MRI, to ensure it reaches the right area.