Tnm Classification For Breast Cancer
The American Joint Committee on Cancer provides two principal groups for breast cancer staging: anatomic, which is based on extent of cancer as defined by tumor size , lymph node status , and distant metastasis and prognostic, which includes anatomic TNM plus tumor grade and the status of the biomarkers human epidermal growth factor receptor 2 , estrogen receptor , and progesterone receptor . The prognostic stage group is preferred for patient care and is to be used for reporting of all cancer patients in the United States.
In turn, prognostic stages are divided into clinical and pathological groups. Pathological stage applies to patients who have undergone surgery as the initial treatment for breast cancer. It includes all information used for clinical staging plus findings at surgery and pathological findings from surgical resection. Pathological prognostic stage does not apply to patients who received neoadjuvant therapy . See the tables below.
Table. TNM Classification for Breast Cancer
What Will You Find On A Pathology Report
The report is broken down into a few sections, including:
- Some information about the patient, such as the clinical diagnosis .
- The procedure that was done to get the body tissue.
- A description of what the specimen looks like to the naked eye .
- A description of what was seen under the microscope .
- A pathologic diagnosis (a diagnosis based on what the pathologist saw under the microscope.
In the case of breast cancer, the pathologist will describe:
- The type of cell the cancer comes from.
- The tumor size and grade.
- Whether the cancer cells have entered the lymph channels or blood vessels.
- Information about surgical resection margins.
- Hormone receptor and Her2 status.
Breast cancer pathology reports are one of the more complex pathology reports and can seem quite overwhelming at first. To help you better understand your report, let’s break down each section by itself.
Checking The Lymph Nodes
The usual treatment is surgery to remove the cancer. Before your surgery you have an ultrasound scan to check the lymph nodes in the armpit close to the breast. This is to see if they contain cancer cells. If breast cancer spreads, it usually first spreads to the lymph nodes close to the breast.
Depending on the results of your scan you might have:
- a sentinel lymph node biopsy during your breast cancer operation
- surgery to remove your lymph nodes
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Treatment To The Breast
Your surgeon might remove the cancerous area with a border of normal breast tissue. This is called breast conserving surgery or a wide local excision. After this you usually have radiotherapy to the rest of the breast.
Or you might have the whole breast removed. This is called a mastectomy. You can choose to have a new breast made . You might have radiotherapy to the chest wall after having a mastectomy. You might have treatment with radiotherapy to the lymph nodes under your arm or further surgery to remove the nodes if they contain cancer cells.
You can have a breast reconstruction at the same time as surgery to remove the cancer, or at a later time. Having a reconstruction at the same time should not affect you having radiotherapy after surgery if you need it. The plan to have radiotherapy after a reconstruction might affect the reconstruction options you have.
Your surgeon will discuss all the pros and cons with you.
You usually have other treatments too.
How Is The Stage Determined

The staging system most often used for breast cancer is the American Joint Committee on Cancer TNM system. The most recent AJCC system, effective January 2018, has both clinical and pathologic staging systems for breast cancer:
- The pathologic stage is determined by examining tissue removed during an operation.
- Sometimes, if surgery is not possible right away or at all, the cancer will be given a clinical stage instead. This is based on the results of a physical exam, biopsy, and imaging tests. The clinical stage is used to help plan treatment. Sometimes, though, the cancer has spread further than the clinical stage estimates, and may not predict the patients outlook as accurately as a pathologic stage.
In both staging systems, 7 key pieces of information are used:
- The extent of the tumor : How large is the cancer? Has it grown into nearby areas?
- The spread to nearby lymph nodes : Has the cancer spread to nearby lymph nodes? If so, how many?
- The spread to distant sites : Has the cancer spread to distant organs such as the lungs or liver?
- Estrogen Receptor status: Does the cancer have the protein called an estrogen receptor?
- Progesterone Receptor status: Does the cancer have the protein called a progesterone receptor?
- HER2 status: Does the cancer make too much of a protein called HER2?
- Grade of the cancer : How much do the cancer cells look like normal cells?
In addition, Oncotype Dx® Recurrence Score results may also be considered in the stage in certain situations.
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N Categories For Breast Cancer
N followed by a number from 0 to 3 indicates whether the cancer has spread to lymph nodes near the breast and, if so, how many lymph nodes are involved.
Lymph node staging for breast cancer is based on how the nodes look under the microscope, and has changed as technology has gotten better. Newer methods have made it possible to find smaller and smaller groups of cancer cells, but experts haven’t been sure how much these tiny deposits of cancer cells influence outlook.
Its not yet clear how much cancer in the lymph node is needed to see a change in outlook or treatment. This is still being studied, but for now, a deposit of cancer cells must contain at least 200 cells or be at least 0.2 mm across for it to change the N stage. An area of cancer spread that is smaller than 0.2 mm doesn’t change the stage, but is recorded with abbreviations that indicate the type of special test used to find the spread.
If the area of cancer spread is at least 0.2 mm , but still not larger than 2 mm, it is called a micrometastasis . Micrometastases are counted only if there aren’t any larger areas of cancer spread. Areas of cancer spread larger than 2 mm are known to influence outlook and do change the N stage. These larger areas are sometimes called macrometastases, but are more often just called metastases.
NX: Nearby lymph nodes cannot be assessed .
N0: Cancer has not spread to nearby lymph nodes.
N1c: Both N1a and N1b apply.
N3: Any of the following:
N3a: either:
N3b: either:
Classifying Breast Cancer Tumors
In addition to using the numerical stage classifications, healthcare professionals also describe tumors using the tumor, node, metastasis staging system.
In this system, T describes tumor size, N describes the presence of cancer cells in the lymph nodes, and M describes whether or not the cancer has spread to other areas of the body.
Here are the possible classifications for tumor size :
- TX: Healthcare professionals cannot measure primary tumor size.
- T0: Healthcare professionals cannot find a tumor.
- T1: The tumor is smaller than 2 centimeters .
- T2: The tumor measures 25 cm.
- T2: The tumor is larger than 5 cm.
- T4: The tumor has spread beyond the breast tissue and lymph nodes or is inflammatory.
Here are the possible classifications for lymph node involvement :
- NX: Healthcare professionals cannot assess the lymph nodes.
- N0: The cancer has not spread to the surrounding nodes.
- N1, N2, N3: These indicate the number of nodes involved.
Here are the possible classifications for metastasis :
- M0: There is no sign that the cancer has spread .
- M1: The cancer has spread to another area of the body.
- MX: The cancer spread is not measurable.
Since 2018, healthcare professionals have added new cancer characteristics to the TNM staging system that may help guide treatment. These include:
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Stage Iib: One Of The Following Applies:
T2, N1, M0: The tumor is larger than 2 cm and less than 5 cm across . It has spread to 1 to 3 axillary lymph nodes and/or tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy . The cancer hasnt spread to distant sites .
T3, N0, M0: The tumor is larger than 5 cm across but does not grow into the chest wall or skin and has not spread to lymph nodes . The cancer hasnt spread to distant sites .
What Is A Pathology Report
A pathologist is a medical doctor who specializes in diagnosing diseases. Pathologists look at tissue from the body that is removed during surgery or a biopsy. You will probably never meet the pathologist, but samples of your breast tissue and lymph nodes will be sent to them for review. The pathologist prepares a summary report of their findings, which is called the pathology report.
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Systems That Describe Stage
There are many staging systems. Some, such as the TNM staging system, are used for many types of cancer. Others are specific to a particular type of cancer. Most staging systems include information about:
- Where the tumor is located in the body
- The size of the tumor
- Whether the cancer has spread to nearby lymph nodes
- Whether the cancer has spread to a different part of the body
- Tumor grade, which refers to how abnormal the cancer cells look and how likely the tumor is to grow and spread
The TNM Staging System
The TNM system is the most widely used cancer staging system. Most hospitals and medical centers use the TNM system as their main method for cancer reporting. You are likely to see your cancer described by this staging system in your pathology report, unless you have a cancer for which a different staging system is used. Examples of cancers with different staging systems include brain and spinal cord tumors and blood cancers.
In the TNM system:
- The T refers to the size and extent of the main tumor. The main tumor is usually called the primary tumor.
- The N refers to the the number of nearby lymph nodes that have cancer.
- The M refers to whether the cancer has metastasized. This means that the cancer has spread from the primary tumor to other parts of the body.
Primary tumor
- MX: Metastasis cannot be measured.
- M0: Cancer has not spread to other parts of the body.
- M1: Cancer has spread to other parts of the body.
Other Ways to Describe Stage
Related Resources
Breast Cancer Support And Resources
There are many resources and support groups for breast cancer survivors. Theres no obligation to stick with a group. You can try it out and move on whenever youre ready. You might be surprised to learn that you have a lot to offer others as well.
The American Cancer Society has a variety of support services and programs. You can call the 24/7 helpline at 800-227-2345, visit the Life After Treatment Guide .
If you like having information at your fingertips, download the free Breast Cancer Healthline app. The app lets you connect with others who have a similar diagnosis and understand what youre going through.
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Supporting Someone With Breast Cancer
If youre reading this because theres a breast cancer survivor in your life, youre already being supportive.
Maybe you dont know what to say or fear saying the wrong thing. Say something anyway. Dont let breast cancer go unmentioned. The best thing you can do now is to be there and let them lead the way.
People with breast cancer may feel obligated to act with confidence and have a positive attitude. That may mask whats really going on. Let them know they can be real with you, then listen without judgment.
Offer to help in a concrete way. Can you prepare a meal? Do some chores? Share a movie night? Let them know what youre willing to do. But take them at their word. If they dont want help, dont push it. Just making the offer lets them know you care.
The end of treatment is not the end of the experience. There are many adjustments ahead. Some things may never return to the way they were, but change isnt always a bad thing.
Want More Information On Breast Cancer Treatments

DCIS
DCIS is a noninvasive condition referring to abnormal cells in the lining of the breast duct that have not spread to other tissues. It is possible for DCIS to become invasive cancer and spread to other parts of the body, so treatment can reduce the likelihood of recurrence. DCIS is considered Stage 0, since it is noninvasive.
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Stage Iv: Any T Any N M:
The cancer can be any size and may or may not have spread to nearby lymph nodes . It has spread to distant organs or to lymph nodes far from the breast . The most common sites of spread are the bone, liver, brain, or lung,
If you have any questions about the stage of your cancer and what it might mean in your case, be sure to ask your doctor.
Stage Iiic: Any T N3 M: The Tumor Is Any Size And One Of The Following Applies:
- Cancer has spread to 10 or more axillary lymph nodes .
- Cancer has spread to the lymph nodes under the clavicle .
- Cancer has spread to the lymph nodes above the clavicle .
- Cancer involves axillary lymph nodes and has enlarged the internal mammary lymph nodes .
- Cancer has spread to 4 or more axillary lymph nodes, and tiny amounts of cancer are found in internal mammary lymph nodes on sentinel lymph node biopsy .The cancer hasnt spread to distant sites .
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T Categories For Breast Cancer
T followed by a number from 0 to 4 describes the main tumor’s size and if it has spread to the skin or to the chest wall under the breast. Higher T numbers mean a larger tumor and/or wider spread to tissues near the breast.
TX: Primary tumor cannot be assessed.
T0: No evidence of primary tumor.
Tis: Carcinoma in situ
T1 : Tumor is 2 cm or less across.
T2: Tumor is more than 2 cm but not more than 5 cm across.
T3: Tumor is more than 5 cm across.
T4 : Tumor of any size growing into the chest wall or skin. This includes inflammatory breast cancer.
How Is Hormone Receptorpositive Breast Cancer Diagnosed
A pathologist will test the breast cancer cells for estrogen or progesterone receptors using special stains on the tumor specimen called immunohistochemistry or IHC. One type of multigene test, the Oncotype DX, may also provide information about the hormone receptor status by measuring the RNA that codes for the development of these receptors on the cell surface.
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How Is Hormone Receptorpositive Breast Cancer Treated
Hormone therapy either blocks the bodyâs ability to produce estrogen or progesterone, or interferes with the effects of hormones on breast cancer cells, which helps to slow or stop the growth of hormone-sensitive tumors.
Ovarian Abation
Ovarian ablation, or treatment that stops or lowers the amount of estrogen made by the ovaries, can be done surgically, through radiation, or using drugs. With surgical treatment or radiation, the ovarian ablation is typically permanent. Suppressing ovarian function with drugs is temporary, and this group of medicines functions by interfering with signals from the pituitary gland stimulating the ovaries to produce estrogen. Side effects of ovarian suppression may include bone loss, mood swings, depression, and loss of libido.
SERMs
Selective estrogen receptor modulators bind to estrogen receptors, preventing estrogen from binding. In addition to blocking estrogen activity, SERMs can also mimic estrogen effects because of their ability to bind. A SERM called tamoxifen, for example, blocks the effects of estrogen in breast tissue but acts like estrogen in the uterus and bone. Tamoxifen is effective in treating early-stage breast cancer after surgery. Some SERMs can treat advanced or metastatic breast cancer. Side effects of tamoxifen may include risk of blood clots, stroke, cataracts, endometrial and uterine cancers, bone loss in premenopausal women, mood swings, depression, and loss of libido.
Aromatase Inhibitors
Genomic Tests To Predict Recurrence Risk
Doctors use genomic tests to look for specific genes or proteins, which are substances made by the genes, that are found in or on cancer cells. These tests help doctors better understand the unique features of each patients breast cancer. Genomic tests can also help estimate the risk of the cancer coming back after treatment. Knowing this information helps doctors and patients make decisions about specific treatments and can help some patients avoid unwanted side effects from a treatment that may not be needed.
The genomic tests listed below can be done on a sample of the tumor that was already removed during biopsy or surgery. Most patients will not need an extra biopsy or more surgery for these tests.
For patients age 50 or younger
-
Recurrence score less than 16: Hormonal therapy is usually recommended, but chemotherapy is generally not needed
-
Recurrence score of 16 to 30: Chemotherapy may be recommended before hormonal therapy is given
-
Recurrence score of 31 or higher: Chemotherapy is usually recommended before hormonal therapy is given
For patients older than 50
The tests listed above have not been shown to be useful to predict risk of recurrence for people with HER2-positive or triple-negative breast cancer. Therefore, none of these tests are currently recommended for breast cancer that is HER2 positive or triple negative. Your doctor will use other factors to help recommend treatment options for you.
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