For Your Patients: The Crucial Role of the Biopsy in Breast Cancer

Most breast cancers are found with breast imaging, but the majority of "suspicious" breast lesions need more evaluation. This is known as a diagnostic workup, and there are two main methods: biopsy and pathology.

What Is a Breast Biopsy?

A breast biopsy is a diagnostic procedure during which a small amount of breast tissue is removed and then examined under a microscope. If the tissue sample shows cancer, the physician can have it analyzed further via pathology.

A breast biopsy can be used to take a closer look at the findings that are first seen on imaging (i.e., by mammogram, ultrasound, or MRI), or other breast examinations, such as a clinical exam by a healthcare provider. The biopsy will offer more specific information about an area in the breast that is of concern.

The breast biopsy can generally determine whether the unusual finding is, or is not, breast cancer. Sometimes, discordance can happen, where imaging shows a suspicious finding but the biopsy result is negative. In those instances, additional testing is needed and surgery may be required.

The pathology report from the breast biopsy can help your doctor determine the treatment plan.

Are All Breast Biopsies the Same?

There are different types of breast biopsy procedures, but they fall into two broad categories: surgical biopsy and needle biopsy.

Your physician will discuss the optimal biopsy type for your situation. There is some preparation needed for a breast biopsy and some level of care afterwards to manage the biopsy site and/or any temporary pain you may experience at the site.

Needle Biopsy

Fine needle aspiration (FNA) biopsy uses a thin needle to remove a small sample of cells from the area in question. Tests may be done for cancer biomarkers that are found on or in the tumor cells.

Core needle biopsy (CNB) uses a wider needle to remove a larger sample of tissue. CNB is generally the preferred biopsy technique because it removes more tissue than FNA, but it does not require surgery. If a tumor is identified on CNB, tests will be done for cancer biomarkers that are found on or in the tumor cells.

Image-guided biopsy involves a needle being guided to the location of the concerning area with the assistance of imaging, such as mammography, ultrasound, or MRI. Both FNA and CNB can be done with image guidance. Another method, called stereotactic biopsy, specifically uses mammography to guide the needle.

In many cases, a small metal clip is placed in the breast at the time of biopsy to mark where the biopsy sample was taken, in the event the tissue is cancerous and more surgery is required. The clip is usually titanium, so it should not be a problem for future imaging tests, but consult with your physician before undergoing any imaging tests during which the presence of metals may be an issue.

Surgical Biopsy

The surgical approach may be an incisional biopsy that removes only part of the concerning area, or an excisional biopsy that removes the entire tumor. A margin or edge of normal breast tissue around the tumor also may be removed, depending on the reason for the biopsy.

Sentinel lymph node biopsy (SLNB) is needed when the cancer has spread through the lymphatic system. The term '"sentinel" refers to the lymph node, or group of lymph nodes, that the cancer reaches first. These are usually lymph nodes under the arms called the axillary lymph nodes. SLNB is used to determine if there is cancer in the lymph nodes near the breast.

Liquid Biopsy

Biomarkers -- short for biological markers -- are measures of a biological state. Liquid biopsy is a noninvasive diagnostic tool that evaluates biomarkers in the blood and other body fluids. "Noninvasive" means that the sample for the liquid biopsy can be obtained with just a blood draw. In general, liquid biopsies are done at this time for metastatic disease.

Four liquid biopsy tests are currently approved by the FDA, meaning that these tests have been evaluated and deemed safe for use in patients.

What Is Cancer Staging?

Staging determines how extensive the breast cancer is, including:

• Tumor size
• Lymph node involvement
• Spread to other distant body parts
• Relevant biomarkers

Clinical staging is done before surgery. Pathologic staging is done after surgery. Information about the stage helps physicians recommend the best kind of treatment and can also help predict prognosis. Different types of cancer have different stage descriptions.

For more on staging, see Part 1 of this Medical Journeys series.

What Is a Pathology Report?

Biopsy samples are sent to a pathology lab and reviewed by a physician called a pathologist. Pathologists will create a report that will help with cancer management and treatment. In general, a pathology report has two components -- a microscopic description, and results about any biomarkers.

A microscopic description is designed to answer questions such as:

• Is the finding cancer?
• How big is the cancer?
• Is it invasive cancer?
• Are there cancer cells in the lymph nodes?

The pathology report will also give information on how different the cancer cells look compared with normal breast cells. The cancer cells are graded, ranging from grade 1 (the cancer cells look a little different than normal cells) to grade 3 (the cancer cells look very different than normal cells).

Results from biomarker testing in the report will cover such topics as:

• Hormone receptors, which help a cancer grow. These receptors are typically characterized as estrogen receptor (ER) positive or negative, progesterone receptor (PR) positive or negative, and HER2 positive or negative.
• Whether the genes and proteins in the cancer cells are normal or abnormal.

During surgery, a rim of normal tissue surrounding the tumor (called a margin) is also removed. The pathology report will include information on the margin status or whether the cancer was fully removed during surgery.

Negative margins indicate that the outer edges or the margins don't contain cancer cells. Negative margins can also be referred to as "clean" or "clear" margins. Positive margins, also called involved margins, indicate that the margins contain cancer cells. Close margins indicate that the cancer cells approach the edge of the removed breast tissue, but do not touch the edge of that tissue.

The pathology report will end with a summary or a final diagnosis.

Read Part 1 of this series: For Your Patients: Breast Cancer Basics

"Medical Journeys" is a set of clinical resources reviewed by physicians, meant for the medical team as well as the patients they serve. Each episode of this journey through a disease state contains both a physician guide and a downloadable/printable patient resource. "Medical Journeys" chart a path each step of the way for physicians and patients and provide continual resources and support, as the caregiver team navigates the course of a disease.