Once the diagnosis of breast cancer is confirmed through various investigations. TNM staging helps to determine the disease prognosis and to select an appropriate treatment strategy.
Before discussing the staging of breast cancer, let’s have a look at the normal anatomy of breast that will help us to understand the staging better.
TNM Staging of Breast Cancer – Explained with Applied Anatomy of Breast and Axillary Lymph Nodes
The staging of breast cancer is called TNM staging. We will discuss this in detail.
It is called as T1 when the tumor size is less than or equal to 2 cm.
T2 when the tumor is 2 cm to 5 cm.
And T3 when the tumor is more than 5 cm.
To understand T4 disease, first we have to know the structures. Deep to the breast there is pectoralls fascia and pectoralls major muscle.
And here lies the pectoralis minor muscle.
Other structures in the chest wall include ribs and intercostal muscles.
If we look from the front of the chest, this is the pectoralis major muscle.
And this is the serratus anterior muscle.
T4a disease is when the tumor infiltrates the chest wall, not including only pectoralis muscle adhesion or invasion.
And here, the tumor infiltrates into the serratus anterior muscle.
T4b disease is involvement of skin by the tumor.
It can present as skin ulceration or as satellite tumor nodules.
Or as edema of skin looking like an orange peel known as peau de orange.
All the skin changes should occupy less than one-third of the surface area of breast to be called as T4b. Infiltration of tumor into both, chest wall and skin, i.e., T4a and T4b both, is called T4c.
And when the breast cancer progresses very rapidly to cause diffuse erythema and edema of skin breast, involving more than one-third of the skin, then it is called as inflammatory breast cancer.
Now, we move on to the N-staging. To understand the N staging, first you have to know the local structures in that area.
In this figure, you can see the humerus, clavicle and sternum bone.
This is the pectoralls minor muscle.
These nodular structures in the anterior axillary fold, are called as anterior group of lymph nodes.
And along the head of the humerus are lateral group of lymph nodes.
All these three groups, lateral to pectoralis minor muscle, are level 1 lymph nodes.
These present behind the pectoralls minor muscle are central, or level 2 lymph nodes.
And these present medial to pectoralls minor muscle, are apical or level 3 lymph nodes.
And these, along the sternum are called as internal mammary lymph nodes.
For clinical N-staging, we have to palpate level 1 and 2 lymph nodes in axilla. If they are not palpable, it is NO. If palpable, and freely mobile, it is N1. If level 1 or level 2 lymph nodes are palpable, but they are fixed or matted, it is called as N2a.
If only internal mammary lymph nodes are seen in CT scan without any level 1 or level 2 nodes, the it is called as N2b.
If infraclavicular lymph nodes are involved, it is called as N3a.
If internal mammary and axillary lymph nodes both are involved that is N2a and N2b, then it is N3b.
Involvement of supraclavicular lymph nodes are called as N3c.
Now, let’s move ahead. Next comes the M-staging, if the disease has spread to the distance organ it is called as M1 otherwise it is M0. This figure shows spread to both lungs in the form or multiple metastatic nodules.
And here, metastasis to the pleura has resulted in fluid collection, called as pleural effusion.
This figure shows spread to the liver in form or multiple nodular deposits.
And here, the cancer is spread to the adrenal gland.
Similarly, the spread may occur to brain, bones or other part of the body.
TNM is the most commonly used system for breast cancer staging. It uses mainly 3 parameters: “T” stands for “Tumor”; “N” for “Lymph Nodes”; and “M” for “Metastasis”. Numbers and/or letters after T (0, is, 1, 2, 3, and 4), N (0, 1mi, 1, 2, and 3), and M (0 and 1) provide more details about each of these parameters. Once T, N, and M are determined, it is used to assign an overall stage (from 0 to IV).
Tis – Pre-cancerous changes or carcinoma in situ (CIS). No spread to nearby lymph nodes or distant body parts.
T1 – Tumor size is 2 cm or less. No spread to nearby lymph nodes or distant body parts.
T2 – Tumor size >2 cm, but </=5 cm. No spread to nearby lymph nodes or distant body parts.
T3 – Tumor size >5 cm. No spread to nearby lymph nodes or distant body parts.
T4 – Tumor of any size with direct extension to the chest wall or skin or inflammatory breast cancer.
N1 – Cancer spread to 1-3 axillary lymph nodes or tiny cancer deposits in internal mammary lymph node(s) on sentinel lymph node biopsy.
N2 – Cancer spread to 4-9 axillary lymph nodes or enlargement of internal mammary lymph node(s).
N3 – >/=10 axillary lymph nodes (>/=1 area >2 mm), or cancer spread to the infraclavicular (those under the collarbone) lymph nodes (>/=1 area >2 mm) [N3a],
Cancer spread to >/=1 axillary lymph nodes (>/=1 area >2 mm) with internal mammary lymph node(s) enlargement, or cancer spread to >/=4 axillary lymph nodes (>/=1 area >2 mm) with micrometastasis in internal mammary lymph node(s)[N3b], or
cancer spread to the supraclavicular (those above the collarbone) lymph nodes (>/=1 area >2 mm)[N3c].
M0 – No spread of the disease to distant body parts.
M1 – Cancer spread to distant organs like bones, lungs, liver, brain, etc.
Localised, Locally Advanced and Metastatic Breast Cancer
To make things easier, we stage the breast cancer into stage groups. It can broadly be divided into localized, locally advanced or metastatic disease.
Localised disease includes cases up to T2 N1 M0 and T3 N0 M0. Starting from T3 N1 M0 and onwards all N2 and N3 and T4 cases are included under locally advanced disease. Metastasis to other sites, as we have discussed previously is called M1 disease.
What are the 4 Stages of Breast Cancer?
Based on the TNM Staging discussed above, breast cancer can be classified into 4 stages as discussed below.
|0||Tis N0 M0|
|IA||T1 N0 M0|
|IB||T0-1 N1mi M0|
|IIA||T0-1 N1 M0|
|T2 N0 M0|
|IIB||T2 N1 M0|
|T3 N0 M0|
|IIIA||T0-2 N2 M0|
|T3 N1-2 M0|
|IIIB||T4 N0-2 M0|
|IIIC||AnyT N3 M0|
|IV||AnyT AnyN M1|
In addition to staging, estrogen receptor (ER), progesterone receptor (PR), HER2/neu (HER2) status, and grade of the cancer is evaluated on the surgical specimen to assess the prognosis of the disease, and planning the treatment.
What are the Investigations for Diagnosis and Staging of Breast Cancer?
If a woman is suspected to have breast cancer due to presence of signs and symptoms, some investigations are required to confirm the diagnosis of the disease. They help in distinguishing between benign breast disease (fibrosis, simple cyst, papilloma, mild hyperplasia, or lobular carcinoma in situ) and the breast cancer.
Further, they can help in determining the stage of tumor, which in turn help in selecting a treatment option.
It uses low dose IX-rays to examine the breasts. In this test, a special machine has used that consist of two plates to compress and flatten the breast to be examined. Thereafter, an X-ray image of the breast is taken. This test can provide information about the cancerous changes within the breast tissue which generally appears as a lump/mass, microcalcifications, or other changes. Any abnormality observed during this test warrants detailed investigations to establish the diagnosis of breast cancer. Mammograms are not very sensitive in case of dense breast tissue.
In this technique, a transducer is used to direct very high-frequency sound waves towards the breast tissue to be examined. The sound waves are reflected off the internal structures depending on their ability to reflect these waves. The reflected sound waves are collected by a special detector (fixed near the transducer) to produce a real-time image of the internal tissues on a computer screen. This test can distinguish between fluid-filled cysts (mostly benign) and solid tumor masses. This technique can also be used to guide a needle to collect biopsy samples.
Biopsy sample is generally collected from the suspected areas observed during the mammography or the breast ultrasound. Depending on the size and location of the suspicious area, a fine needle biopsy, a core needle biopsy, or a surgical biopsy technique is utilized. Sometimes, a biopsy sample from lymph nodes under the arms may also be collected. The collected biopsy samples are examined in a laboratory and can provide information about the type of cancer, grade of cancer, and the presence of specific defective genes or proteins in the cancer cells. Breast cancer is classified into hormone receptor positive, Her-2 Neu positive or triple negative disease based on biopsy testing and it is very important as it determines the further treatment of the disease.
These tests are generally employed after the establishment of the pathological diagnosis. They help to detect the spread of disease to distant body parts and assess the stage of the disease so that an appropriate treatment option can be selected. Alternatively, these tests are employed after treatment to evaluate the treatment efficacy and to detect disease response, progression, or recurrence.
Computed tomography (CT) scan
In this technique, detailed cross-sectional images of body organs are generated using x-rays, with or without a contrast medium. It can help diagnose the spread of disease to nearby/distant lymph nodes and other organs, and may also be used to guide a biopsy needle into the affected area.
Magnetic resonance imaging (MRI) scan
This technique provides detailed images of tissues inside the body using radio waves, a strong magnetic field, and gadolinium contrast. It can accurately diagnose the extent of invasion and spread of disease to nearby/distant body parts.
Positron emission tomography (PET) scan
This technique uses a radioactive substance (e.g.fluorodeoxyglucose [FDG]) that is given intravenously prior to the procedure. Cancer cells absorb larger amounts of the radioactive substance than normal cells. The areas of higher radioactivity indicate cancerous tissue on the PET scan. Thus, this technique can diagnose the spread of disease to distant body parts. It is usually combined with a CT scan (PET/CT).
In this test, a radioactive material is injected into the vein of the patient, which gets accumulated in the areas of bones affected by the disease, which are then detected with the help of radioactivity detectors. In this way, it may help to detect the spread of cancer to bones.
This is relatively less-sensitive imaging technique that can reveal the spread of cancer to lungs or pleura. Spread to lungs or pleura may appear as nodule(s), pleural effusion, etc.
Watch this video to better understand the INVESTIGATIONS for diagnosing and staging breast cancer.
In this video, CancerBro will explain the process of how breast cancer is diagnosed.
Imaging for breast cancer requires local imaging of the breast, and in some cases, whole body imaging called as systemic imaging.
Mammography is done in all the cases of breast cancer. In some cases, mammography may be inadequate, when ultrasound or MRI of the breast may be required.
In advanced disease or symptoms related to distant organ involvement, systemic imaging may be required, such as whole-body CT scan, bone scan, MRI brain or PET CT.
Mammography imaging of the breast is reported as a score called BIRADS score.
BIRADS 1 means absolutely normal breast, with 0% chances of malignancy.
BIRADS 2 means the presence of benign findings, with 0% chances of malignancy.
BIRADS 3 means the presence of findings that are probably benign, with less than 2% chances of malignancy. Needle testing of breast is not required in BIRADS 1, 2 or 3.
BIRADS 4 means suspicious for malignancy, with 2-95% chances of malignancy. Needle testing should be considered in this.
BIRADS 5 means highly suggestive of malignancy, with more than 95% chances of malignancy. Needle testing should be done in this.
Needle testing of breast may be done by FNAC or biopsy, but biopsy is preferred as it is more accurate, and provides sufficient tissue for ER, PR and HER-2 testing.
So first we did a local imaging when we had a suspicious mass in breast. Then we did a needle testing to confirm that it is cancer.
Once the diagnosis of breast cancer is confirmed, we have to do the systemic imaging depending upon clinical presentation, to stage the disease, whether it is localized, locally advanced or metastatic.
This completes the diagnostic work-up for breast cancer.
What is the Survival Rate/ Life Expectancy according to Stage of Breast Cancer?
Survival rates give you an idea of percentage of people that are alive 5 years after being diagnosed with breast cancer. It does not tell how long they live, but helps in better understanding of the treatment response. Also, what needs to be understood is that these survival rates are an average of the patients with same type and stage of cancer, that are compared to general population without the disease.
It is calculated based on whether the disease is Localised, Regional or Distant.
- Cancer is limited to the breast.
- 5 year survival 99%.
- Cancer has spread to nearby structures or lymph nodes
- 5 year survival 86%.
- Cancer has spread to distant body parts.
- 5 year survival 27%.
What are the Symptoms of Advanced Stage (Stage 4) Breast Cancer?
Symptoms of advanced disease may be caused due to local involvement of nearby structures and metastasis to distant sites.
Local spread may cause:
- Lump or thickening in the breast and/or axilla
- Diffuse asymmetrical change in size or shape of breast
- Skin changes over the breast like dimpling, puckering, tethering, etc
- Abnormal nipple discharge, nipple inversion/ flattening
Distant spread may cause:
- Back pain or pain at one or more bony site
- Headache, altered sensorium, nausea, vomiting and/or seizures
- Cough, breathlessness, chest pain or discomfort
- Yellowish discoloration of eye and/or urine
Most common sites of spread of breast cancer are bone, brain, liver and lung.