A breast biopsy involves taking a small sample of breast tissue so it can be examined under a microscope.

Your doctor might order a breast biopsy after finding something suspicious on a mammogram or ultrasound. A biopsy is the only way to determine if a breast lump is noncancerous (benign) or cancerous (malignant).

After thorough analysis, a pathologist prepares a detailed report. It contains a lot of information and terms you may not be familiar with.

In this article, we’ll discuss some of the main items included in breast biopsy results and talk about what happens next.

Following are some items that might appear on your pathology report following a needle biopsy.

  • specimen/gross description, such as the size, weight, and color of the tissue being analyzed
  • microscopic description, which tells how the cells look under a microscope
  • special tests or markers for proteins and cell growth rate
  • diagnosis or summary of the findings

The main result from a breast biopsy is whether the tissue sample contained cancer cells. Research from 2019 suggests that about 75 percent of breast biopsies performed in the United States come back with a benign (noncancerous) result.

Keep in mind that different labs may use different terminology and your report may go into greater detail.

Benign means the tissue sample didn’t contain cancer cells. Some benign conditions and changes are:

If you see the words “high risk” on your report, it means that you may have a condition associated with higher risk of developing breast cancer in the future. Some of these are:

A malignant result means that cancer cells were found in the sample. Your report will provide additional information about the cancer.

Invasive or noninvasive

If the report includes the words “ductal carcinoma in situ (DCIS),” it means you have noninvasive cancer. This type of cancer stays within the milk duct where it started. DCIS is considered stage 0 breast cancer or pre-cancer.

Invasive cancers can invade nearby tissue and spread beyond the breast. They’re sometimes called infiltrating cancers. These include invasive ductal carcinoma (IDC), which begins in the milk duct, and invasive lobular carcinoma (ILC), which begins in the lobules.

Hormone receptors

Breast cancers are checked for estrogen receptors (ER) and progesterone receptors (PR). They’re reported separately as positive, weakly positive, or negative. Some labs also show a percentage or a 0 to 8 score.

If your cancer tests positive for these hormone receptors (HR), the cancer is using hormones to fuel growth. This is important because it means you can benefit from hormone therapy.

HER2

Breast cancer is checked for overexpression of a protein called human epidermal growth factor receptor 2, or HER2. Using immunohistochemistry (IHC) testing, the results are reported as:

  • 0 or 1+: HER2-negative
  • 3+: HER2-positive
  • 2+: unclear or equivocal

An unclear result means that further testing is needed. Overexpression of HER2 can make breast cancer grow and spread faster. But a positive result means that your treatment can include drugs that target HER2.

Grade

Grade describes how different the cells look compared to normal cells, as well as how fast they’re reproducing.

  • Grade 1 means the cancer cells are well-differentiated. They look a look a little different from normal cells and are usually slow growing.
  • Grade 2 covers moderately differentiated cancer cells. They don’t look normal and are growing at a faster rate than normal cells.
  • Grade 3 means the cancer cells are poorly differentiated. They look a lot different from normal cells are growing much faster.

If your pathology report states that the cells were benign, that means no breast cancer was found. Your doctor will give you the particulars of the diagnosis. If the biopsy results aren’t clear to you, consider asking:

  • Do I need any kind of treatment right now?
  • Is this something that I should follow up on? If so, when and how?
  • Am I at higher risk of breast cancer in the future? Does this change when and how I should be screened?

If the pathology report indicates breast cancer, it’s likely your next step will be to visit with a breast cancer specialist, such as a breast surgeon or oncologist.

Your detailed pathology report will help with clinical staging of the cancer. The stage, along with breast cancer type, will help guide the next steps. These may include additional tests or scans to see if the cancer has spread to other areas such as nearby tissues or more distant organs.

Your doctor might also recommend genetic testing at this time. This can determine if you carry gene mutations associated with other types of cancer as well.

If surgery is indicated to remove the tumor, the surgeon will take more samples for biopsy. This will generate a new pathology report with additional information such as:

Your oncologist can use this information to decide if your treatment plan needs adjusting.

Waiting for breast biopsy results can be a stressful time. And when you get them, the medical terminology can be rather confusing.

The big piece of information is whether the sample contains cancer cells. If not, it will describe what was found and your doctor can advise you on whether you need treatment or follow-up testing.

If the sample does contain cancer cells, the report will specify if it’s invasive or noninvasive. It will also include other details, such as HR and HER2 status, that can help determine your best treatment options.

Additional biopsies will happen during surgery to remove the tumor. That pathology report will add to what’s already known and help guide the rest of your breast cancer treatment.

When in doubt about your breast biopsy results, it’s best to speak with your oncologist.