Testing for cancer

A variety of tests can be used when detecting, diagnosing or monitoring cancer. There are two main types of tests used for these purposes:

• screening tests
• diagnostic tests

Screening tests are used for people who do not have any symptoms of cancer but are at high risk for developing certain types of cancer. For many types of cancer, progress in the area of cancer screening has offered promise for earlier detection, which often results in higher cure rates.

St. Peter’s Health is proud to offer Low dose Computed Tomography (LDCT) scans, an early detection screening method that has been proven to save lives of people at a high risk for lung cancer. This lung cancer screening program is recommended for a highly targeted set of invidividuals who are between ages 55 and 77, are still smoking or quit smoking within the past 15 years and who have a “30-pack year” or more smoking history. If you are interested in a lung cancer screening or have more questions, contact our lung navigation unit at 406-447-2661. Our staff will review your risk with you and determine if a LDCT scan is appropriate for you. 

Diagnostic tests are used to accurately diagnose disease, determine prognosis, and monitor cancer for progression or recurrence, predict prognosis, direct treatment, evaluate response to treatment, and monitor remission or progression.

Genetic testing is another area of screening. Predictive genetic testing is used to determine if an individual has a genetic mutation that may predispose him/her to developing cancer. St. Peter’s Cancer Care works with genetic testing in cooperation with Shodair Hospital.

Imaging tests use x–rays, magnetic fields, or radioactive substances to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, including to help find out whether a suspicious area might be cancerous, to learn how far cancer may have spread, and to help determine if treatment has been effective.

In many cases, imaging tests can give doctors a reasonable amount of certainty that mass is (or is not) cancerous. In some cases, however, a biopsy may be needed to be sure. The most common types of imaging tests are:

Computed Tomography (CT or CAT) Scan

The CT or CAT scan is an x–ray test that produces detailed cross–sectional images of your body. Instead of taking one picture, like a regular x–ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures into images of slices of the part of your body being studied. Unlike a regular x–ray, a CT scan creates detailed images of the soft tissues in the body.

Magnetic Resonance Imaging (MRI)

Like CT scans, MRI scans provide detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x–rays.

The energy from the radio waves is absorbed and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. A contrast material called gadolinium is often injected into a vein before the scan to better see details.

MRI scans are a little more uncomfortable than CT scans. First, they take longer—often up to an hour. Second, you have to lie inside a narrow tube, which is confining and can upset people with claustrophobia (a fear of enclosed spaces).

Ultrasound (ultrasonography or US)

Ultrasound uses sound waves to create images of internal organs. For this test, a small, microphone–like instrument called a transducer is placed on the skin near, say, the kidney. It emits sound waves and picks up the echoes as they bounce off the tissues in the kidney. The echoes are converted by a computer into a black–and–white image that is displayed on a computer screen. This test is painless and does not expose you to radiation.

Positron Emission Tomography (PET) Scan

PET scans involve injecting a form of radioactive sugar into the blood. The amount of radioactivity used is very low. Because cancer cells in the body are growing rapidly, they absorb large amounts of the radioactive sugar.

A special camera can then create a picture of areas of radioactivity in the body. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about your whole body. This test can be useful to see if the cancer may have spread to lymph nodes near the kidney.

PET scans can also be useful if your doctor thinks the cancer may have spread but doesn't know where. PET scans can be used instead of several different x–rays because they scan your whole body.

PET/CT Scan

A PET/CT exam combines the use of two imaging techniques to give your doctor unique information about your body. The exam provides a picture of anatomy (CT) merged with pictures of your body’s function (PET). The merged imaging provides valuable information on your body’s structure and metabolism that will help your doctor provide the best possible care for you.

Intravenous Pyelogram (IVP)

An intravenous pyelogram is an x–ray of the urinary system taken after a special dye is injected into a vein. This dye travels from the bloodstream into the kidneys and then passes into the ureters and bladder. An IVP can be useful in finding abnormalities of the urinary tract, such as cancer, but you might not need an IVP if you have already had a CT or MRI.

Angiography

Like the IVP, this x–ray test also uses a contrast dye. A catheter is usually threaded up a large artery in your leg. The dye is then injected into the artery to outline blood vessels. Because angiography can outline the blood vessels that supply a kidney tumor, it can help a surgeon plan an operation.

Angiography can also help diagnose renal cancers since the blood vessels usually have a special appearance with this test.

Bone Scan

A bone scan can help show if a cancer has metastasized (spread) to your bones.

For this test, a small amount of low–level radioactive material is injected into a vein (intravenously, or IV). The substance settles in areas of damaged bone throughout the entire skeleton over the course of a couple of hours. You then lie on a table for about 30 minutes while a special camera detects the radioactivity and creates a picture of your skeleton.

Transvaginal ultrasound (or Sonography)

For a transvaginal ultrasound a probe that gives off sound waves is inserted into the vagina, which creates images of the uterus and other pelvic organs. These images often help show whether a tumor is present and may be able to determine if it is growing into the muscle layer of the uterus (myometrium).

Lab tests are done to get a sense of a person's overall health and to help tell if cancer may have spread to other areas. Prior to surgery, they can help tell if a person is healthy enough to have an operation.

Urinalysis (urine testing) is sometimes part of a complete physical exam, but it may not be done as a part of more routine physicals. It is likely to be one of the first tests done if kidney cancer is a possibility.

Microscopic and chemical tests are done on the urine to look for small amounts of blood and other substances not seen with the naked eye. About half of all patients with renal cell cancer will have blood in their urine. Sometimes special microscopic examination of urine samples (called urine cytology) will show actual cancer cells in the urine.

Complete Blood Count

Blood counts are important to make sure a person is healthy enough for surgery.

Blood chemistry tests are sometimes done to see what affect a cancer is having on the levels of certain chemicals in the blood.  For example, high blood calcium levels may indicate that cancer has spread to the bones and may therefore prompt a doctor to order a bone scan.

Biopsies

Endometrial Biopsy

An endometrial biopsy is the most commonly–performed test for endometrial cancer. It can be done in the doctor’s office.

In this procedure, a very thin flexible tube is inserted into the uterus through the cervix. Then, using suction, a small amount of endometrium is removed through the tube. The suctioning takes about a minute or less. The discomfort is similar to menstrual cramps and can be helped by taking a nonsteroidal anti–inflammatory drug such as ibuprofen before the procedure.

Fine Needle Aspiration (FNA) Biopsy

A fine needle aspiration (FNA) biopsy is sometimes used to get a small sample of cells from a suspicious area if imaging test results are not conclusive enough. It may also be done to confirm the diagnosis of cancer if a person's health is too poor for surgery, and other local treatments are being considered.

For this test, the skin where the needle is to be inserted is first numbed with local anesthesia. Unlike ultrasound, CT doesn't provide a continuous picture, so the needle is inserted in the direction of the mass, a CT image is taken, and the direction of the needle is guided based on the image. This is repeated a few times until the needle is within the mass.

A small sample of the target area is sucked (aspirated) into a syringe and looked at under the microscope to see if cancer cells are present.

Open Incisional Biopsy

An open incisional biopsy involves a wide incision through the skin in order to expose the suspicious mass so that a tissue sample can be removed and analyzed in a laboratory.

Percutaneous Biopsy

A percutaneous biopsy is an effective method for making a diagnosis before surgery. Since most patients are currently treated with neoadjuvant chemotherapy, it is important to make the diagnosis prior to surgery.

A percutaneous core needle biopsy is a procedure in which a small needle with a hollow core is placed into the suspicious mass and a tissue sample is collected. This procedure uses computed tomography (CT) or fluoroscopy to help guide the biopsy needle.

Cystoccopy and proctoscopy 

If a woman has problems that suggest the cancer has spread to the bladder or rectum, the inside of these organs can be looked at through a lighted tube.

In cystoscopy the tube is placed into the bladder through the urethra. In proctoscopy the tube is placed in the rectum.

These exams allow the doctor to look for possible cancers. Small tissue samples can also be removed during these procedures for pathologic (microscopic) testing. They can be done using a local anesthetic, but some patients may require general anesthesia. Your doctor will let you know what to expect before and after the procedure.

These procedures were used more often in the past, but now are rarely part of the work–up for endometrial cancer.

 This information is from the American Cancer Society website, www.cancer.org