Understanding Pathology Results: What Does It All Mean?

The words used to define the type of breast cancer you have are not always easy to understand. This guide can help prepare you to speak with your doctor about the results.

During my first oncology appointment after I learned I had breast cancer, I sat nervously awaiting the details of my diagnosis. A few days earlier, I’d had an ultrasound followed by a needle biopsy of a suspicious lump I found in one of my breasts. When the radiologist called to give me the results of that biopsy, telling me the tissue was malignant, she’d had few other details to share.

At what would be a whirlwind 3-hour first appointment with all the doctors and other medical professionals I’d see during my treatment, I finally received the document I thought would answer all my questions: the pathology report from my biopsy.

But after scanning the report, I had more questions than answers. While I understood the stage 2 diagnosis, other words on the pages confounded me. “Carcinoma.” “Microcalcifications.” “HER2.” What did these things mean?

While my oncologist did a great job of explaining everything, I realized that some people may not be so lucky. Understanding your pathology results, which describe how the disease affects your body’s cells and tissues, can help you better interpret your diagnosis and treatment options.

With that in mind, here’s a basic guide to some words you may see on your pathology report. As always, it’s important to speak with your doctor directly to clarify any parts of your report that you don’t understand.

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Carcinoma

This term describes a malignant growth that starts in the epithelial cells of organs such as the breast. The epithelial cells can be within glands or line the ducts. Almost all breast cancers are carcinomas.

In-situ carcinoma

This term refers to breast cancer cells that have not broken through the walls of the ducts or lobules where they formed.

Invasive or infiltrating carcinoma

Breast cancer cells generally form inside the ducts or lobules. If they break through into the surrounding area, they are considered invasive or infiltrating.

Size

The size of breast cancer is usually measured at its widest point, in millimeters or centimeters. Tumor size factors into cancer staging.

If you’re having a needle biopsy that removes only a portion of the affected area, your report may not include information on size.

Stage

Breast cancer is staged from stage 0 (carcinoma in situ) to stage 4. As a rule, the lower the stage, the less the cancer has spread.

Breast cancer is staged with the TNM system:

• “T” represents the size of the primary tumor and whether it involves the outside of the breast or the chest wall.
• “N” stands for spread to nearby lymph nodes, with a higher number meaning more are affected.
• “M” represents metastasis (spread of cancer cells to distant parts of your body), which is measured through different testing and not through the pathology report.

Once the TNM categories are established, the cancer is given an overall stage number.

Differentiation and grade

This refers to how likely cancer is to grow and spread based on features such as:

• the arrangement of cells in relation to each other
• whether the cells form tubules (gland formation)
• whether they resemble normal breast cells (nuclear grade)
• how many cells are in the process of dividing (mitotic count)

Healthcare professionals look at all these features together to determine whether carcinomas are:

• well differentiated (likely to grow and spread slowly)
• poorly differentiated (likely to grow and spread more quickly)
• moderately differentiated (somewhere between the previous two in behavior and outlook)

These features are assigned numbers to help determine the histologic grade, which is also sometimes referred to as the Nottingham or Elston grade.

The sum of the numbers indicates the grade:

• 3–5 is grade 1 cancer (well differentiated)
• 6–7 is grade 2 (moderately differentiated)
• 8–9 is grade 3 (poorly differentiated)

Tubular, mucinous, cribriform, or micropapillary

These are different types of invasive ductal carcinoma. A pathologist identifies the type by looking at the tissue under a microscope. Knowing the type of carcinoma can help your doctor determine a course of treatment specific to your needs.

Vascular, lymphovascular, or angiolymphatic invasion

This means some cancer cells appear in small blood vessels or lymph vessels. If your cancer has moved to these areas, it may influence the treatment plan your doctor suggests.

Axillary and sentinel lymph nodes

These lymph nodes are located in your underarm. The sentinel node is the first one to which your tumor drains.

In a sentinel node biopsy, a surgeon will remove that node, as it is most likely to contain cancer if the cancer has spread from your breast. If no cancer is found in the sentinel node, it’s unlikely that the cancer has spread to additional lymph nodes.

Microcalcifications

These are calcium deposits that can be found in both cancerous and noncancerous breast lesions. They can often be seen on mammograms and ultrasounds.

Estrogen or progesterone receptors

Receptors are proteins in cancer cells that can attach to estrogen or progesterone hormones. These hormones often fuel the growth of breast cancer.

If your cancer is ER-positive or PR-positive, your doctor can use hormone therapy to change how the hormones in your body interact with the cancer.

HER2/HER2 status

Breast cancer cells that have too much of a growth-promoting protein are referred to as HER2-positive. HER2-positive cancers tend to grow and spread more quickly. Again, knowing whether this protein is a factor can help guide treatment decisions.

Triple-negative or triple-positive

These terms describe breast cancers that are either negative for both hormone receptors (estrogen and progesterone) and HER2 or positive for all three.

Margins

When a tumor is removed, the outside edges (margins) are coated with ink. This allows the pathologist to look at slides of the tumor under a microscope to determine how close the cancer cells are to the ink.

If cancer cells are touching the ink, that is referred to as a positive margin and can indicate that some cancer was left behind and additional surgery or other treatments may be needed.

Takeaway

The most important thing to remember when reading your pathology report is that you can ask your oncologist or pathologist about anything you don’t understand. Your doctors should explain every aspect of the report thoroughly so that you can feel confident in your diagnosis and treatment plan.