Understanding your pathology report

The pathology report is one of the most important documents you will receive during the diagnostic process. This report is a profile of the cancer’s characteristics, including stage, how quickly it may grow, hormone-receptor status, and HER2 status. Your oncologist then uses this information to recommend treatments for you.

How are pathology reports created? When breast tissue is surgically removed to look for cancer, it’s sent to the lab for study. A medical doctor specially trained to study this tissue and identify diseases, called a pathologist, analyzes the tissue under a microscope and interprets test results. The pathologist then writes the report and shares it with your doctor. Your doctor will give you a copy and add the report to your medical record.

How to read a pathology report

We know that pathology reports can be very technical and difficult to understand. We’re here to walk you through each part.

A pathology report is created any time tissue is removed from your body for examination, whether you’re having a biopsy or a bigger surgery, such as lumpectomy, mastectomy, or removal of lymph nodes, tiny organs that help the body filter out harmful substances. Your complete pathology report may arrive all at once, or in pieces as different test results arrive.

Your doctor may recommend that some of the tissue from your biopsy or other surgery be sent out for additional tests. These can include tumor biomarker (genomic) tests, such as Oncotype DX and MammaPrint, that predict the likelihood of cancer coming back. The results from these tests are separate and not part of the pathology report.

Sections of a pathology report

Below, you can find specific information about each piece of a pathology report, including what the breast tissue looks like, the cancer stage, cancer grade, how quickly the cells divide, the margin and lymph node status, and other test results.

Your name, your doctor’s name, and tissue specimen details

The first section of a pathology report usually includes your name, date of birth, and a number that identifies your samples. Next, you’ll see the name of the lab that sampled the tissue along with contact information for the pathologist and your oncologist.

You’ll also see the type of biopsy or surgery that was done and the kind of tissue contained in the sample.

If you had a biopsy, you’ll see the technical name for the type of biopsy you had. Here are the most common types of breast cancer biopsies:

• Fine-needle aspiration
• Core needle biopsy
• Incisional or excisional biopsy
• Sentinel node dissection

Learn more about what’s involved in a breast cancer biopsy.

If you had a more significant surgery, you will see the name of your surgery. Here are the most common types of surgery to remove breast cancer:

• Lumpectomy (also known as wide excision or partial breast excision)
• Mastectomy
• Axillary node dissection

You may also see the term resection, which means surgery that removes tissue or organs.

Learn more about surgery.

If any information is incorrect or missing, let your doctor know.

Location of the tumor or tissue that was removed

The following terms may be used to describe where the removed tumor or tissue was located:

• Anatomic site is the location of the tumor (the breast ducts or lymph nodes, for example). Anatomic refers to a part of your body: in this case, the part of your body that contains the breast cancer. Tumors can grow in any part of the breast, and can be cancerous or non-cancerous.
• Multicentric breast cancer means multiple cancerous tumors in the breast, all separate from one another, often located in different sections, or quadrants, of the breast.
• Multifocal breast cancer means two or more cancerous tumors in one area or quadrant of the breast, less than 2 to 5 centimeters apart.

Gross description

In this section, the pathologist describes the color, size, texture, and weight of the tissue or tumor as seen with the naked eye.

Diagnosis

The diagnosis section may be at the beginning or end of the report, and contains the main take-home information: whether or not the cells are cancerous, the behavior and characteristics of the cancer cells, the cancer type (such as ductal or lobular carcinoma), grade, margin status, lymph node status, hormone-receptor status, HER2 status, and stage.

Words used to describe non-cancerous breast cell changes

• Hyperplasia is a benign (non-cancerous) breast condition. In the breast, hyperplasia means there is increased cell growth within the milk ducts or milk-producing glands (lobules), resulting in more cells than would usually be there. If the cells look abnormal, they may be classified as atypical hyperplasia. There are two types of atypical hyperplasia:
  • Atypical ductal hyperplasia (ADH): These abnormally growing cells, found in a milk duct, have some features of ductal carcinoma in situ, but not all of the features. While ADH is not cancer, it may mean an increased risk of breast cancer both in the area (locally) and elsewhere in both breasts. Talk with your doctor about a risk-reducing follow-up plan.
  • Atypical lobular hyperplasia (ALH): ALH is a group of abnormally growing cells in a breast lobule. In part like ADH, ALH can mean an increased risk of breast cancer to both breasts, so talk with your doctor about any risk-reducing steps you can take.
• Lobular carcinoma in situ (LCIS) means that cells that look like cancer, but are not cancer, are found in the glands (lobules) that produce milk in the breast. LCIS does not spread outside of the lobule, but it can mean an increased risk of invasive breast cancer to both breasts, so it’s important to talk to your doctor about a follow-up plan.

Words used to describe characteristics of breast cancer

• Carcinoma is a term for cancer that starts in the cellular lining of organs and tissues, called epithelial cells. Adenocarcinoma is a more specific term for cancers that resemble glands; for example, cancers that form in the milk ducts or glands (lobules) in the breast.
• Non-invasive or invasive: Breast cancer can be limited to growing inside of breast structures (non-invasive) or it can progress and go into surrounding breast tissue (invasive). Cancer cells that start to grow in the ducts or in the lobules — the structures that make and carry breast milk to the nipples — become invasive if they have gone outside the ducts or lobules into surrounding non-glandular breast tissue.
  • Non-invasive breast cancer is contained within the breast ducts and has not grown beyond the duct. On the pathology report, this cancer may be called intraductal carcinoma, ductal carcinoma in situ, or DCIS.
  • Invasive (also called infiltrating) breast cancer has broken out of the ducts or lobules into surrounding breast tissue.
    • Invasive breast cancer includes:
      • Invasive ductal carcinoma (IDC)
      • Invasive lobular carcinoma (ILC)
      • Less common breast cancers, such as:
        • Inflammatory breast cancer (IBC), an aggressive breast cancer that is often invasive ductal carcinoma, but often does not form a lump and spreads quickly, causing breast swelling, redness, and sometimes an orange peel-like appearance on the skin
        • Medullary breast cancer, an invasive breast cancer that:
          • Features rapidly dividing cells
          • Is often triple-negative (does not have hormone receptors or HER2 receptors)
          • Is usually found before it reaches the lymph nodes
        • Mucinous carcinoma (MC), a type of invasive breast cancer in which:
          • Cancer cells are surrounded by a substance called mucin, an ingredient of mucus
          • Cancer cells are usually low-grade, which means the cells are not as aggressive as higher grade cancers
          • The cancer is less likely to spread to the lymph nodes
        • Tubular carcinoma (TC), a low-grade invasive breast cancer that forms into tube or gland-shaped structures and is not as likely as other breast cancers to spread to the lymph nodes
    • Invasive breast cancer can spread to areas outside the breast, such as the lymph nodes.
    • Invasive breast cancer can also metastasize, or spread to other parts of the body including the bones, liver, lungs, or brain.
• Size describes how large or small the cancer is. The size of an invasive tumor is important for you and your doctors to know as you plan your treatment. Generally, smaller tumors are associated with less intense treatment, better results, and longer survival. Larger tumors are usually treated more aggressively and are associated with shorter survival and higher risk for recurrence, the chance that the cancer will return or spread to other parts of the body.

• Tumor grade (sometimes called histologic grade) describes what invasive cancer cells look like when compared with normal cells. You may see “Nottingham grade” mentioned; this is the most common system of grading and depends on scores that the pathologist determines by analyzing the tumor’s amount of gland or tubule formation (whether the cancer has formed into a tube shape), the nuclear features of the tumor cells (how the nucleus of a cancer cell looks compared to a normal cell), and the number of cells dividing (mitoses). Grade has three categories:
  • Grade 1: Low grade or well differentiated means the cancer cells look more like normal cells in appearance. These cancer cells tend to grow and spread more slowly.
  • Grade 2: Intermediate grade or moderately differentiated means the tumor tissue and tumor cells look somewhat different from healthy tissue and healthy cells, but not completely different.
  • Grade 3: High grade, or poorly differentiated, means the cancer cells look very different from healthy tissue and healthy cells. These cancer cells tend to grow and spread more quickly.

• Mitotic rate describes how quickly the cells are dividing. This helps the pathologist determine the cancer grade. If a tumor does not have many dividing cells, it’s generally a low-grade tumor.

• Tumor margin is the area of cells at the edges of the tissue that has been removed. If you had a surgical biopsy, lumpectomy, or mastectomy, tumor margin will be mentioned on the report.
  • A positive margin means cancer cells have been found in the margin, and there are likely to be additional cancer cells remaining in the body.
  • Your surgeon’s goal is to remove all of the cancer in your breast and achieve clear or negative margins, meaning they find no cancer at the edge of the tissue they remove. Clear margins are associated with a lower risk of cancer returning in the same breast.

Research shows about 1 out of 4 women who have a lumpectomy go on to have a second breast surgery because the margins weren’t clear after their first surgery. If you have more than one tumor in a breast, it’s harder to achieve clear margins with a lumpectomy. In this situation, your surgeon may recommend mastectomy instead.

• Lymphovascular invasion, also called lymphatic invasion, means that cancer cells have entered the lymph channels in the breast. Blood vessels carry blood throughout the body, while lymph channels carry bacteria-fighting lymph fluid throughout the body. Lymphatic invasion, vascular invasion, or both, raise the risk that the cancer has or will spread to other areas of the body, or that it may come back after treatment. It does not mean that the cancer has definitely spread to other areas of your body. If your report mentions lymphovascular invasion, talk with your doctor about what it means for you and your treatment options. If your report doesn’t mention lymphovascular invasion, it means that there is none.

• Lymph node status describes whether or not there are cancer cells in the lymph nodes under the arm (axillary nodes). If you had lymph node surgery, you will see this on your report. When cancer is found in a lymph node, the node is called positive. If none is found, the node is called negative. If there is metastasis, the pathologist will measure the largest size of any individual one and note if the tumor has spread into fatty tissue surrounding the lymph node (also known as extranodal or extracapsular extension) and its size.
  • Lymph node status can include the status of the sentinel node, the first lymph node where cancer is most likely to spread from a tumor, if you had a sentinel node biopsy.
  • If a large amount of cancer is found in the lymph nodes and the largest area of cells measures more than 2 millimeters, the area of spread is called macrometastasis, and you may see pN1 or pN2 or pN3 on your pathology report, depending on the number of positive lymph nodes.
  • If a very small amount of cancer is found in the lymph nodes and the cells measure at least 0.2 millimeters, but not more than 2 millimeters, the area of spread is called micrometastasis. You may see pN1(mi) on your pathology report if lymph node micrometastasis is found.
  • If areas of cancer even smaller than a micrometastasis are found in the lymph nodes, they are called isolated tumor cells (ITCs). If ITCs are found, you may see pN0(i+) on your pathology report. This is a classification for lymph node cancer cells measuring less than or equal to 0.2 millimeters.

The presence or absence of cancer cells in your lymph nodes helps the pathologist to stage the cancer, and helps you and your doctor decide what treatments you may need in addition to surgery. Even if an area of lymph node cancer cells is tiny, it’s important to talk with your doctor about possible treatment options that can lower the risk of breast cancer recurrence.

It’s easy to confuse lymph node status with lymphovascular invasion, but they are different. Lymphovascular invasion means the pathologist saw some cancer cells in the lymph channels within your breast, rather than in the lymph nodes themselves. Vascular invasion is cancer cells within blood vessels and is far less common.

• Hormone receptor status describes whether the cancer cells have receptors (proteins) that attach to estrogen (estrogen-receptor positive or negative) or progesterone (progesterone-receptor positive or negative). The immunohistochemistry (IHC) test is the most common test used to look for hormone receptors on cancer cells. Learn more about hormone-receptor status and how it impacts treatment decisions.
• HER2 status describes whether the cancer has too many copies of the HER2/neu gene, which means the cancer has too much of a growth-fueling HER2 protein. Testing for HER2 status includes:
  • Immunohistochemistry (IHC) testing to look for HER2 receptors
  • In situ hybridization (ISH) testing to look for extra copies of the HER2 gene in cancer cells

HER2-positive breast cancers are more aggressive than other breast cancers. Learn more about HER2-positive breast cancer.

• Stage describes the extent and behavior of the cancer. To determine stage, pathologists look at the size, grade, lymph node status, and hormone-receptor and HER2 status of the cancer. Learn more about staging.

Synoptic report, or summary

If cancer was removed, a summary, sometimes called a synoptic report, will appear in table format on the report. The table contains the results considered to be most important in determining treatment.

A comments section is sometimes included if the diagnosis is unusual or unclear. This is where the pathologist can provide additional context about a diagnosis.

Microscopic description

Your pathology report may have a section called “Microscopic description,” or it may not. This section is considered to be optional at many hospitals. If your report does contain a microscopic description section, this is a place where the pathologist may describe how the cells appear under a microscope. This can include cellular changes that are cancerous or non-cancerous. The main information about the cancer will appear in the Diagnosis or Synoptic report section.

Other information in a report

In some cases, your doctor may order additional tissue testing. Some tissue testing happens after the original pathology report is created. Results from those tests are added to the report later, in an addendum. One example of a test result you may see on an addendum is the Ki-67 proliferation index. Test results for estrogen and progesterone receptors and HER2 also often appear on an addendum.

The Ki-67 proliferation index, also known as MIB-1, reports what percentage of invasive cancer cells are growing or multiplying. Ki-67 is a protein made by cells in the process of reproducing. This makes it a good measure of how many cancer cells are growing and multiplying.

• If the percentage of cancer cells making Ki-67 is low, it means the number of cells reproducing is also low.
• If the percentage of cells making Ki-67 is high, it means the number of cells reproducing is high.
• A percentage over 30 percent is considered to be high. This means that many cells are dividing and the cancer is more aggressive.

Ki-67 is not the same as mitotic rate. The mitotic rate is reported as part of the cancer’s grade. Not all pathologists perform this test, so you may not see it on your pathology report.

Seeking a second opinion

After you receive your pathology report and you’ve discussed possible treatment options with your doctor, it’s not unusual to have questions or concerns that might lead you to seek a second opinion. People seek second opinions for many reasons. If you’re unclear about your doctor’s recommendations or want to feel confident that the pathology is correct, for instance, you may decide to get another doctor’s opinion about your choices. Another reason to seek a second opinion is if you want to find a hospital conducting clinical trials for your cancer type. In addition, a second pathology opinion may be required as part of the process before getting care at a different institution.

If you decide to seek a second opinion, you may be asked to gather and send medical records to the second opinion doctor. Your doctor’s office can help you coordinate the process with the second opinion doctor.

To learn more, visit Should you get a second opinion?

Next steps

Your pathology report can help you and your doctor decide the best care plan for you. Understanding each piece of information can help you talk with your doctor about how different treatment options work and which treatments might be right for you.

Whether you’ve had a biopsy, lumpectomy, or mastectomy, your pathology report provides a blueprint for your next steps. In Preparing for treatment, we’ll share tips on how you can help yourself feel physically and emotionally ready.

We know that planning cancer treatment can trigger feelings such as anxiety, sadness, or anger. Visit Emotional health for guidance, support, and stories from others.