Why do I need a biopsy?

Because in most cases it is the only way to be certain. There is no single test that diagnoses cancer, and imaging and blood work can only point in a direction. A biopsy takes actual tissue so a pathologist can look at the cells themselves.

Why the other tests are not enough

Lab tests can suggest cancer, but NCI is blunt about their limits. For many tests it is possible to have normal results even if you have cancer, and possible to have abnormal results even if you are healthy.

Normal ranges come from testing large numbers of people in the past, and they shift with age, sex, race, medical history, and general health. Your own results vary from day to day. That is why results are reported as a range with upper and lower limits rather than a single line.

Imaging has the same problem in a different form. A CT scan, MRI, ultrasound, PET, or bone scan can show something that should not be there, but a picture cannot tell benign from malignant. Only cells can.

What the biopsy actually produces

A pathologist examines the tissue under a microscope and runs further tests on the cells. The findings go into a pathology report, which contains the details of your diagnosis.

That report does more than confirm cancer. It helps show which treatment options might work for you. Later steps depend on it too, including grading the tumor, sorting you into a risk group, and testing the tissue for tumor markers or biomarkers that match specific drugs. Without tissue, most of that is impossible.

How the sample is taken

There are three main routes, and the one you get depends on where the abnormal area is.

With a needle. The doctor withdraws tissue or fluid. This is how bone marrow aspirations, spinal taps, and many breast, prostate, and liver biopsies are done.

With an endoscope. A thin, lighted tube goes in through a natural opening. A colonoscopy passes through the anus to examine the colon and rectum. A bronchoscopy goes through the mouth or nose and down the throat to reach the windpipe, airways, and lungs. Tissue can be removed through the scope.

With surgery. In an excisional biopsy, the surgeon removes the whole abnormal area, usually with a margin of normal tissue. In an incisional biopsy, they take only part of it.

Some biopsies use a sedative, which helps you relax or sleep and stay still. Some use anesthesia, which prevents pain. Local anesthesia numbs one small area, regional numbs a limb or region, and general causes complete loss of awareness. Ask which applies to yours, since that determines whether you can drive home.

The wait, and the portal

Results from labs, imaging, and biopsies often appear in your patient portal before your doctor has seen them. NCI names this directly and says it is normal to feel anxious and want to know right away.

Two things help. Decide in advance whether you want to open results before the appointment, because you can choose not to. And bring the report to the visit, since your doctor is the person who can put all your tests together and say what they mean for you.

If a biopsy result comes back unclear, that is not unusual, and it sometimes means a repeat or a larger sample. Ask what the next step would be before you leave. Our overview of how cancer is diagnosed covers the full test sequence, and the piece on tumor markers explains what blood tests can and cannot show.

Sources

• https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis