PDFs by language
Our 24/7 cancer helpline provides support for people dealing with cancer. We can connect you with trained cancer information specialists who will answer questions about a cancer diagnosis and provide guidance and a compassionate ear.
Chat live online
Select the Live Chat button at the bottom of the page
At our National Cancer Information Center trained Cancer Information Specialists can answer questions 24 hours a day, every day of the year to empower you with accurate, up-to-date information to help you make educated health decisions. We connect patients, caregivers, and family members with valuable services and resources.
Or ask us how you can get involved and support the fight against cancer. Some of the topics we can assist with include:
For medical questions, we encourage you to review our information with your doctor.
When your breast was biopsied, the samples taken were studied under the microscope by a specialized doctor with many years of training called a pathologist. The pathologist sends your doctor a report that gives a diagnosis for each sample taken. Information in this report will be used to help manage your care. The questions and answers that follow are meant to help you understand medical language you might find in the pathology report from a breast biopsy, such as a needle biopsy or an excision biopsy.
In a needle biopsy, a needle is used to remove a sample of an abnormal area. An excision biopsy removes the entire abnormal area, often with some of the surrounding normal tissue. An excision biopsy is much like a type of breast-conserving surgery called a lumpectomy.
Carcinoma is a term used to describe a cancer that begins in the lining layer (epithelial cells) of organs like the breast. Nearly all breast cancers are carcinomas. Most are the type of carcinoma that starts in glandular tissue, which are called adenocarcinomas.
These words are used to mean that the cancer is not a pre-cancer (carcinoma in situ), but is a true cancer.
The normal breast is made of tiny tubes (ducts) that end in a group of sacs (lobules). Cancer starts in the cells lining the ducts or lobules, when a normal cell becomes a carcinoma cell. As long as the carcinoma cells are still confined to the breast ducts or lobules, without breaking out and growing into surrounding tissue, it is considered in-situ carcinoma (or carcinoma in situ).
Once the carcinoma cells have grown and broken out of the ducts or lobules, it is called invasive or infiltrating carcinoma. In an invasive carcinoma, the tumor cells can spread (metastasize) to other parts of your body.
Breast carcinomas are often divided into 2 main types: invasive ductal carcinoma and invasive lobular carcinoma, based on how they look under the microscope. In some cases, the tumor can have features of both and is called a mixed ductal and lobular carcinoma. Another term for invasive ductal carcinoma is invasive mammary carcinoma of no special type, because it is the most common type of breast carcinoma.
Both invasive ductal carcinomas and invasive lobular carcinomas arise from the cells lining the ducts and lobules in the breast. In general, invasive lobular and invasive ductal carcinomas of the breast aren’t treated differently.
E-cadherin is a test that the pathologist might use to help determine if the tumor is ductal or lobular. (The cells in invasive lobular carcinomas are often negative for E-cadherin.) If your report does not mention E-cadherin, it means that this test was not needed to tell what type of cancer you have.
When looking at the cancer cells under the microscope, the pathologist looks for certain features that can help predict how likely the cancer is to grow and spread. These features include the arrangement of the cells in relation to each other, whether they form tubules (gland formation), how closely they resemble normal breast cells (nuclear grade), and how many of the cancer cells are in the process of dividing (mitotic count). These features taken together determine how differentiated the cancer is (and its grade – see below).
These grades are similar to what is described in the question above about differentiation. Numbers are assigned to different features (gland formation, nuclear grade, and mitotic count) seen under the microscope and then added up to assign the grade.
Ki-67 is a way to measure how fast the cancer cells are growing and dividing. High values (over 30%) for Ki-67 mean that many cells are dividing, so the cancer is likely to grow and spread more quickly.
These are different types of invasive ductal carcinoma that can be identified under the microscope.
If your doctor knows that your tumor is made up of one of these special types of breast cancer, different treatment might be recommended.
Since some tumors are made up of more than one type, the entire tumor must be removed (by lumpectomy or mastectomy) in order to know what types your tumor contains. A needle biopsy doesn’t give enough information to guide treatment.
If cancer cells are seen in small blood vessels or lymph vessels (lymphatics) under the microscope, it is called vascular, angiolymphatic, or lymphovascular invasion. When cancer is growing in these vessels, there is an increased risk that it has spread outside the breast. If your report does not mention this type of invasion, it means it is not there. Even if it is there, it does not always mean that your cancer has spread. How this finding affects your treatment is best discussed with your doctor.
D2-40 and CD34 are special tests that the pathologist may use to help identify these types of vascular invasion. These tests are not needed in every case.
If the entire tumor or area of cancer is removed, the pathologist will say how big the area of cancer is by measuring how long it is across (in greatest dimension), either by looking at it under the microscope, or by gross examination (just looking at it with the naked eye) of the tissue removed during surgery. The size of the tumor in the breast is part of what determines the stage (extent) of the cancer, which influences treatment and prognosis.
A needle biopsy only samples a part of the tumor, so measurements of the size of the cancer are often not given. Later, when the tumor is removed (by mastectomy or breast-conserving surgery), a more accurate measurement is obtained.
The stage of a cancer is a measurement of the extent of the tumor and its spread. The standard staging system for breast cancer uses a system known as TNM, where:
If the stage is based on removal of the cancer with surgery and review by the pathologist, the letter p (for pathologic) may appear before the T and N letters.
The T category (T0, Tis, T1, T2, T3, or T4) is based on the size of the tumor and whether or not it has spread to the skin over the breast or to the chest wall under the breast. Higher T numbers mean a larger tumor and/or wider spread to tissues near the breast. (Tis is carcinoma in situ.) Since the entire tumor must be removed to learn the T category, this information is not given for needle biopsies.
The N category (N0, N1, N2, or N3) indicates whether the cancer has spread to lymph nodes near the breast and, if so, how many lymph nodes are affected. Higher numbers after the N indicate more lymph node involvement by cancer. If no nearby lymph nodes were removed to be checked for cancer spread, the report may list the N category as NX, where the letter X is used to mean that the information is not available (also see next question).
The M category (M0, M1) is usually based on the results of lab and imaging tests, and is not part of the pathology report from breast cancer surgery. In a pathology report, the M category is often left off or listed as MX (again the letter X means that the information is not available).
Once the T, N, and M categories have been determined, this information is combined to give the cancer an overall stage. Stages are expressed in Roman numerals from stage I (the least advanced stage) to stage IV (the most advanced stage). Non-invasive cancer (carcinoma in situ) is listed as stage 0.
Detailed information on staging can be found in Stages of Breast Cancer. Talk with your doctor about the stage of your cancer and what it means to you.
If breast cancer spreads, it often goes first to the nearby lymph nodes under the arm (called axillary lymph nodes). If any of your underarm lymph nodes were enlarged (found either by physical exam or with an imaging test like ultrasound or mammogram), they may be biopsied at the same time as your breast tumor. One way to do this is by using a needle to get a sample of cells from the lymph node. The cells will be checked to see if they contain cancer and if so, whether the cancer is ductal or lobular carcinoma.
In surgery meant to treat breast cancer, lymph nodes under the arm may be removed. These lymph nodes will be examined under the microscope to see if they contain cancer cells. The results might be reported as the number of lymph nodes removed and how many of them contained cancer (for example, 2 of 15 lymph nodes contained cancer).
Lymph node spread affects staging and prognosis (outlook). Your doctor can talk to you about what these results mean to you.
In a sentinel lymph node biopsy, the surgeon finds and removes the first lymph node(s) to which a tumor drains. This lymph node, known as the sentinel node, is the one most likely to contain cancer cells if they have started to spread. This procedure may be done during surgery to remove a breast cancer. It is a way to check for the spread of cancer to underarm lymph nodes without removing as many of them.
The sentinel lymph node is then checked to see if it contains cancer cells. If there is no cancer in the sentinel node(s), it's very unlikely that the cancer has spread to other lymph nodes, so no further lymph node surgery is needed.
If a sentinel lymph node does contain cancer, your report will say that cancer was present in the lymph node. It may also say how large the deposit of cancer cells is. In some cases, if cancer is found in a sentinel lymph node, you may then also need additional treatment such as surgery to remove more underarm lymph nodes or radiation therapy to the underarm region. You should discuss this with your doctor.
This means there are scattered cancer cells in the lymph node that are either seen with a routine microscopic exam or with special tests. Isolated tumor cells do not affect your stage or change your treatment.
This means that the isolated tumor cells were found in a lymph node using special stains.
This means that there are cancer cells in the lymph nodes that are bigger than isolated tumor cells but smaller than regular cancer deposits. If micrometastases are present, the N category is described as pN1mi. This can affect the stage of your cancer, so it might change what treatments you may need. Talk to your doctor about what this finding may mean to you.
These are special tests that the pathologist sometimes uses to help diagnose invasive breast cancer or to identify cancer in lymph nodes. Not all cases need these tests. Whether or not your report mentions these tests has no bearing on the accuracy of your diagnosis.
All of these are terms for non-cancerous (benign) changes that the pathologist might see under the microscope. They are not important when seen on a biopsy where there is invasive breast cancer.
Microcalcifications or calcifications are calcium deposits that can be found in both non-cancerous and cancerous breast lesions. They can be seen both on mammograms and under the microscope. Because certain calcifications are found in areas containing cancer, their presence on a mammogram may lead to a biopsy of the area. Then, when the biopsy is done, the pathologist looks at the tissue removed to be sure that it contains calcifications. If the calcifications are there, the doctor knows that the biopsy sampled the correct area (the abnormal area with calcifications that was seen on the mammogram).
These are terms for certain atypical or pre-cancer changes that can sometimes be seen on biopsy that aren’t as serious as invasive cancer. If they are found in a needle biopsy that also shows invasive cancer, they are typically not important. They may, however, need to be removed completely as a part of treatment. If they are seen on an excisional biopsy at or near a margin (see the question below about margins), more tissue may need to be removed (even if all of the invasive cancer was taken out).
Receptors are proteins on cells that can attach to certain substances, such as hormones, that circulate in the blood. Normal breast cells and some breast cancer cells have receptors that attach to the hormones estrogen and progesterone. These 2 hormones often fuel the growth of breast cancer cells.
An important step in evaluating a breast cancer is to test a portion of the cancer removed during the biopsy (or surgery) to see if they have estrogen and progesterone receptors. Cancer cells may contain neither, one, or both of these receptors. Breast cancers that contain estrogen receptors are often referred to as ER-positive (or ER+) cancers, while those containing progesterone receptors are called PR-positive (or PR+) cancers. Women with hormone receptor-positive cancers tend to have a better prognosis and are much more likely to respond to hormone therapy than women with cancers without these receptors.
All breast cancers and pre-cancers, with the exception of lobular carcinoma in situ (LCIS), should be tested for these hormone receptors when they have the breast biopsy or surgery.
Results for ER and PR are reported separately and can be reported in different ways:
How the results of your tests will affect your therapy is best discussed with your doctor.
Some breast cancers have too much of a growth-promoting protein called HER2/neu (often just shortened to HER2). The HER2/neu gene instructs the cells to make this protein. Tumors with increased levels of HER2/neu are referred to as HER2-positive.
The cells in HER2-positive breast cancers have too many copies of the HER2/neu gene, resulting in greater than normal amounts of the HER2 protein. These cancers tend to grow and spread more quickly than other breast cancers.
All newly diagnosed breast cancers should be tested for HER2, because women with HER2-positive cancers are much more likely to benefit from treatment with drugs that target the HER2 protein, such as trastuzumab (Herceptin), lapatinib (Tykerb), pertuzumab (Perjeta), and T-DM1 (Kadcyla).
Testing of the biopsy or surgery sample is usually done in 1 of 2 ways:
Many breast cancer specialists think that the FISH test is more accurate than IHC. However, it is more expensive and takes longer to get the results. Often the IHC test is used first:
A newer type of test, known as chromogenic in situ hybridization (CISH), works similarly to FISH, by using small DNA probes to count the number of HER2/neu genes in breast cancer cells. This test looks for color changes (not fluorescence) and doesn't require a special microscope, which might make it less expensive than FISH. Right now, it is not being used as much as IHC and FISH.
If your cancer is HER2-positive, your doctor might add certain drugs to your treatment. How the results of your tests will affect your treatment is best discussed with your doctor.
When an entire tumor is removed, the outside edges (or margins) of the specimen are coated with ink, sometimes even with different colors of ink on different sides of the specimen. The pathologist looks at slides of the tumor under the microscope to see how close the cancer cells get to the ink (the edges or margins of the specimen). If cancer cells are touching the ink (called positive margins), it can mean that some cancer was left behind, and more surgery or other treatments may be needed. Sometimes, though, the surgeon has already removed more tissue (at surgery) to help make sure that this isn’t needed.
Sometimes, all of the invasive cancer is removed, but there may be pre-cancer or another serious condition at or near the margin, such as ductal carcinoma in situ (DCIS) or lobular carcinoma in situ (LCIS).
If your pathology report shows positive margins, your doctor will talk to you about what treatment is best.
Molecular tests such as Oncotype DX® and MammaPrint® may help predict the prognosis of certain breast cancers, but not all cases need these tests. If one of these tests is done, the results should be discussed with your treating doctor. The results will not affect your diagnosis, but they might affect your treatment.
This series of Frequently Asked Questions (FAQs) was developed by the Association of Directors of Anatomic and Surgical Pathology to help patients and their families better understand what their pathology report means. These FAQs have been endorsed by the College of American Pathologists (CAP) and reviewed by the American Cancer Society.
Learn more about the FAQ Initiative
Last Revised: August 6, 2020
Copyright 2017 Association of Directors of Anatomic and Surgical Pathology, adapted with permission by the American Cancer Society.