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NCCN Guidelines for Patients



Rectal Cancer, Version 1.2017


The only way to know if you have cancer is to test

tissue. A biopsy is a procedure that removes samples

of fluid or tissue for testing. A biopsy is advised

before receiving treatment.

Rectal biopsy

First, your doctor will perform a digital rectal exam.

Your doctor will put a glove on his or her hand.

Lubricant will be applied to his or her index finger.

Next, your doctor will insert this finger into your

rectum. He or she will be able to feel your rectum

and nearby tissue.

Before the biopsy, your rectum may be numbed

to prevent pain. For samples near your anus, an

anoscope will be used. This is a round, hollow tool

that has a light. It will be inserted a few inches into

your rectum. For distant samples, a sigmoidoscope

will be used. This tool is shaped like a tube. It has a

light, camera, and cutting device.

Needle biopsy

Samples of tissue or fluid can sometimes be

removed from the body with a needle. This procedure

is called a needle biopsy. The methods of obtaining

samples with a needle differ based on the body

site. If your doctor suspects metastases, a needle

biopsy may be done. The samples will be sent to a

pathologist for cancer testing.

Cancer cell tests

Tissue removed from your body will be sent to a

pathologist. This may be tissue from a biopsy or

surgery. The pathologist will examine the samples

using a microscope.

Pathology report

The pathologist will study the parts of the cells to

classify any disease. This is called histologic typing.

When cancer is found, he or she will do other tests to

learn more about the cancer.

One important test result is the cancer grade. The

cancer grade is a score assigned by the pathologist.

He or she will rate the cancer based on how the

cancer cells look. The score is a sign of how fast the

cancer will likely grow and spread. Higher scores

mean that the cancer will likely grow and spread fast.

All lab results are recorded in a pathology report.

A report will be written each time tissue is removed

from your body and tested for cancer. These reports

are vital to planning treatment.

Review your pathology report(s) with your doctor. Ask

questions if you don’t understand. This information

can be complex. It’s also a good idea to get a copy of

your pathology report(s) and take notes.

Molecular testing

Not all rectal cancer cells are alike. Cancer cells can

differ by which genes have mutations. Some gene

mutations are known to have an effect on cancer

treatment. Molecular testing includes tests of genes

or their products (proteins). Molecular testing that is

advised for rectal cancer is described next.

RAS mutation

RAS is a family of proteins found in cells. Some

rectal cancers have abnormal genes that control

the RAS proteins. As a result, the RAS proteins are

overactive and promote cancer cell growth. Some


Treatment planning



Cancer cell tests