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Tumor Typing

Reviewed by Laura J. Martin, MD on October 17, 2020

When you have a tumor, the first signs are often unusual symptoms that you can’t explain. It could be pain, loss of appetite, or bleeding.

And with breast, thyroid, or testicular cancer, you might see or feel a lump. Sometimes a friend or loved one notices it first. Or maybe your doctor will find it, either on an X-ray or during a physical exam.

At first, the doctor may not be able to tell much about the mass. It could be benign (non-cancerous) or malignant (cancerous), and the cause could be any number of things.

They’ll go through a series of steps to find out if it’s cancer and, if so, to narrow down the type of tumor as much as possible. This is “tumor typing.”

This process gives you and your doctor important information about the nature of your disease and the best treatment.

There are a few basic steps to tumor typing:

  • Imaging
  • Sampling of the tumor (biopsy)
  • Laboratory examination of the tumor
  • Gene analysis of the tumor

Imaging

Your doctor may suggest an imaging test to help figure what’s causing your symptoms. Each test takes pictures of the inside of your body; but what they use to do that varies. Tests you might get include:

  • X-ray: Uses a small amount of radiation
  • CT scan: Combines several different X-rays
  • Ultrasound: Uses sound waves
  • PET scan: For this test, the doctor will inject a small amount of a radioactive chemical into a vein. Diseased cells absorb it and show up on the scan.
  • MRI: Uses a magnetic field and computer-generated radio waves

If a tumor is already clearly visible on an imaging test, these images can give important detail about the size, nature, and location of the mass.

There may even be signs that suggest whether the mass is cancer and what type.­­

Still, there is more work ahead to confirm the diagnosis.

Biopsy

Here, the doctor takes a piece of the tumor to test. They can do this in different ways, depending on the size and location of the growth. They might use a needle (this is called a needle biopsy). Sometimes they’ll pair it with a suction device.

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Or they might do a laparoscopic biopsy. The doctor will make a small cut and guide a laparoscope, a thin, flexible tube with a tiny video camera on in the end, into the opening. They’ll make extra openings for tools to take the tissue sample with.

A dermatologist sometimes removes an entire suspicious growth from the surface of your skin and tests it. This is called a skin biopsy. On the other hand, a lung doctor (pulmonologist) might use a tool that goes down your throat to sample a growth on your lung. They’ll call this an endoscopic biopsy.

In some cases, your doctor may decide to remove an entire mass inside your body, either because of its size or because it’s so hard to reach that a small biopsy isn’t worthwhile. This is known as an excisional biopsy. Or they could do an incisional biopsy to remove a small part of a larger tumor.

Your doctor may get an idea whether a growth is cancerous or not simply by looking at it. More often, a special doctor called a pathologist needs to look at the tissue samples under a microscope.

The first part of this examination is sometimes done during the biopsy procedure to give your doctor a better idea of how much tissue they need to remove.

Laboratory Examination of the Tumor

In the lab, a doctor will slice the tumor into thin samples and “fix” (or attach) them onto slides to examine under a microscope. The person doing this is a pathologist, a doctor who specializes in the examination of tumors and other unusual cells in the body.

These samples may confirm whether the tumor is primary or secondary. For example, you might have a tumor in your breast, but under the microscope the cells appear to be lung cancer cells. That means the cancer started in your lungs (primary) and traveled to your breast (secondary).

The pathologist also often applies stains to the samples. Certain types of cancer will absorb the stain, while normal cells won’t.

All this gives more detailed information about the nature of your tumor and helps the pathologist zero in on the right tests in the next typing step: gene testing.

Gene Testing of Tumor Tissue

Doctors call this test, or set of tests, a cancer mutation panel. Your doctor and pathologist will decide how many genes to test. They may discuss this with you as well.

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One gene might suggest you have an aggressive type of cancer, while another could be linked to a slow-growing type. This information can help you and your doctor decide on the best treatment program.

For example, there are new cutting-edge drugs designed specifically to treat tumors with certain gene mutations. For some types of cancer, there is just one gene that can help with treatment planning. For others, there are several.

Some common mutations include EGFR and PDL1 for lung cancer; and BRCA1 and BRCA2 for breast and ovarian cancers.

Stage, Grade, or Type

The “stage” of your cancer is a measure of how far your cancer has spread. The “grade” of your tumor is a measure of how different the cells are from normal cells in that area.

Your doctor might use tumor typing along with your “tumor grade” and your “cancer stage” to create your treatment plan. But grade and stage are different from typing.

WebMD Medical Reference

Sources

SOURCES:

Daniel William Dubovsky, MD, oncologist, Atlanta Cancer Center.

National Health Service (U.K.): “X-ray.”

National Institute of Biomedical Imaging and Bioengineering: “X-rays.”

Mayo Clinic: “CT scan,” “MRI,” “Needle biopsy,” “Ultrasound.”

Cleveland Clinic: “PET Scan.”

American Cancer Society: Laparoscopy,” “Types of biopsies used to look for cancer.”

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