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Understanding the Breast Cancer Stages: The TNM Staging System

Breast cancer stage is determined based on the size and spread of the tumor, involvement of lymph nodes, and presence of metastasis. The TNM system is commonly used to classify stages. In addition to these factors, other tests such as imaging scans and biopsies may also be used in determining the stage of breast cancer.

TNM Staging System for Breast Cancer

The TNM staging system is widely used in cancer diagnosis and treatment. It is a standardized method of describing the extent or severity of a cancer based on:

  1. The size and location of the primary tumor (T)
  2. The involvement of nearby or distant lymph nodes (N), and
  3. The presence or absence of metastasis (M).

For breast cancer, this staging system is essential in determining the type, severity, and potential spread of the disease. It also helps healthcare professionals make informed decisions about treatment options and to optimize improvements in patient outcomes. Treatment plan and prognosis vary depending on the stage.

Para sa kanser sa suso, ang staging system na ito ay mahalaga sa pagtukoy sa uri, kalubhaan, at potensyal na pagkalat ng sakit. Tinutulungan din nito ang mga healthcare professionals na gumawa ng pinaka angkop na desisyon tungkol sa mga opsyon sa paggamot para sa pinaka mabisang gamutan. Ang treatment plan at prognosis ay maaring magiba depende sa stage ng kanser sa suso.

The 'T' value focuses on the size of the original tumor. It's marked with a 'T' and a number or symbol to specify the extent of the tumor's spread. There are six stages for 'T':

  • TX

    Tumor cannot be assessed

  • T0

    No signs of the primary tumor

  • TIS

    Carcinoma in situ, such as ductal carcinoma or Paget’s disease without a related tumor

  • T1

    Tumor is 2 centimeters or smaller

  • T2

    Tumor is more than 2 cm but not more than 5 cm (2 inches) across

  • T3

    Tumor is more than 5 centimeters across

  • T4

    Any size tumor that has invaded nearby organs and tissues like the chest wall or skin

The 'N' category reveals if cancer has reached nearby lymph nodes. Signified by 'N' and a number, it indicates the number of affected lymph nodes:

  • NX

    Cancer in nearby lymph nodes cannot be measured

  • N0

    No spread to nearby lymph nodes

  • N1

    Spread to 1-3 axillary lymph nodes on the same side on the underarm, and/or internal mammary lymph nodes

  • N2

    Spread to 4-9 axillary lymph nodes on the same side on the underarm, and/or internal mammary lymph nodes

  • N3

    Divided into N3a, N3b, and N3c, this stage indicates an extensive spread, including spread to more than 10 axillary/underarm nodes, or nodes near or above the collarbone, or in internal mammary nodes on the same side plus at least one axillary node, or spread to at least 4 underarm lymph nodes and to the breast bone lymph nodes

The 'M' values reflect metastasis, or the spread to distant body parts:

  • M0

    Cancer has not spread to other parts of the body (detected through imaging tests)

  • M1

    Metastasis detected in distant organs (most often to the bones, lungs, brain, or liver), confirmed by imaging and biopsy showing at least a 0.2-millimeter spread

References:

  • PennMedicine.org (Abramson Cancer Center). Breast Cancer Staging. Available at: https://www.pennmedicine.org/cancer/types-of-cancer/breast-cancer/breast-cancer-staging.

Breast Cancer Stages

There are five stages in breast cancer as classified by the TNM staging system: stage 0, stage I, stage II, stage III, and stage IV.

Stage 0

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Stage 0 breast cancer is also known as carcinoma in situ or pre-cancerous breast lesions. At this stage, the cancer cells are still confined to the ducts (ductal carcinoma in situ or DCIS) or lobules (lobular carcinoma in situ or LCIS) of the breast and have not spread to surrounding tissues.

Signs and Symptoms:

  • No physical signs or lumps are present in the breast
  • Abnormal mammogram results showing calcifications or small clusters of abnormal cells

Learn more about Breast Cancer Signs & Symptoms

Early detection through regular screenings and breast self-examination can improve treatment outcome for those diagnosed with breast cancer. With advancements in technology and research, new methods for detecting and treating breast cancer are constantly emerging, giving hope to those fighting this disease.

Stage I

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Stage I breast cancer is divided into two sub-stages based on the tumor size:

  • Stage IA: Tumor size is equal to or less than 2 centimeters with no spread to nearby lymph nodes.
  • Stage IB: No tumor is found in the breast, but small clusters of cancer cells (micrometastases) are present in 1-3 nearby lymph nodes.

Signs and Symptoms:

  • A lump or thickening in the breast or underarm area
  • Changes in breast size or shape

While the most common symptom of breast cancer is a breast lump (located in the breast to under the armpit), it is possible to have breast cancer with no lump. Know the other signs and symptoms of breast cancer here.

If you detect a lump or experience any symptoms related to breast cancer, it is vital to see a doctor immediately to ensure timely evaluation and treatment. Early intervention can significantly improve treatment outcomes and overall prognosis.

To help you prepare for your doctor’s appointment, list down all your symptoms and check out these six questions you should ask your healthcare provider.

Stage II

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Stage II breast cancer is divided into two sub-stages based on the tumor size and spread:

  • Stage IIA: Tumor size is between 2 to 5 centimeters with no spread to nearby lymph nodes, or tumor size is less than 2 centimeters with small clusters of cancer cells in 1-3 nearby lymph nodes.
  • Stage IIB: Tumor size is between 2 to 5 centimeters with small clusters of cancer cells in 1-3 nearby lymph nodes, or tumor size is greater than 5 centimeters with no spread to nearby lymph nodes.

Signs and Symptoms:

  • A lump or thickening in the breast or underarm area
  • Changes in breast size or shape
  • Nipple discharge or nipple inversion

It is important to note that it’s possible to have breast cancer without detecting a breast lump. Know the other signs and symptoms here.

If you discover a lump or experience potential breast cancer symptoms, take action immediately. Consulting a doctor not only ensures timely evaluation but also enhances treatment success and prognosis.

To make the most of your appointment, jot down all your symptoms and consider these six essential questions to discuss with your healthcare provider.

Stage III

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Stage III breast cancer is divided into three sub-stages based on the extent of spread:

  • Stage IIIA: Tumor size may vary, with cancer cells present between 1 and 9 lymph nodes of the underarm or has enlarged the lymph nodes of the internal mammary area.
  • Stage IIIB: Tumor may be any size and has spread to nearby tissues such as the chest wall or skin of the breast. It may also involve up to 9 nearby lymph nodes.
  • Stage IIIC: Tumor may be any size and has spread to 10 or more nearby lymph nodes, or it has spread to distant areas such as under or above the collarbone, ribcage, or in underarm area and has enlarged the internal mammary lymph nodes.

Signs and Symptoms:

  • A lump or thickening in the breast or underarm area
  • Changes in breast size or shape
  • Nipple discharge or nipple inversion
  • Skin changes or inflammation in the breast area
  • Pain or tenderness in the breast

Learn more about Breast Cancer Signs & Symptoms

If you find a lump or have breast cancer symptoms, see a doctor immediately. Remember, early detection saves lives!

Before your visit, note your symptoms and review these key questions to ask your healthcare provider

Stage IV

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Stage 4 breast cancer, is considered the most advanced stage of breast cancer. In this stage, the cancer has spread beyond the breast to other parts of the body such as the bones, lungs, liver, or brain, or to lymph nodes far from the breast. The tumor can be any size (any T) and may or may not have spread to nearby lymph nodes (any N).

Signs and Symptoms:

  • Persistent pain in a specific area: As the cancer cells spread to other parts of the body, they can cause pain in different areas such as bones or organs.
  • Difficulty breathing or chest pain: If the cancer has spread to the lungs, it can lead to difficulty breathing or chest pain.
  • Unintentional weight loss: As the cancer continues to grow and spread, it can lead to a decrease in appetite and weight loss.
  • Fatigue: Stage 4 breast cancer can also cause extreme fatigue due to the body's constant fight against the cancer cells.
  • Changes in bowel or bladder habits: If the cancer has spread to organs such as the liver or intestines, it can affect their functioning and cause changes in bowel or bladder habits.
  • Jaundice: In some cases, stage 4 breast cancer may spread to the liver and result in jaundice, a yellowing of the skin and whites of the eyes.

It is important to note that these symptoms can also be caused by other health conditions, and it is always best to consult a doctor for proper diagnosis and treatment. Regular breast cancer screenings can help detect breast cancer at an earlier stage when it is more treatable. Early detection and personalized treatment based on stage and individual factors greatly increase the chances of survival for breast cancer patients.

References:
1. Mahul B Amin et.al. The 8th Edition AJCC Cancer Staging Manual: Continuing to build a bridge from a populations-based to a more "personalized" approach to cancer staging. CA Cancer J Clin. 2017 Mar;67(2):93-99. (DOI: https://doi.org/10.3322/caac.21388).
2. Breastcancer.org. Breast Cancer Stages. Available at https://www.breastcancer.org/pathologt-report/breast-cancer-stages.
3. CancerCenter.org. What are the signs and symptoms of breast cancer?. Available at: https://www.cancercenter.com/cancer-types/breast-cancer/symptoms.

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Other Factors Considered in Breast Cancer Staging

Estrogen Receptor (ER) and Progesterone Receptor (PR) Status:

  • ER and PR are hormone receptors found in and on breast cancer cells. These receptors bind to estrogen and progesterone, which can promote cancer cell growth.
  • Cancers that test positive for these receptors (ER-positive, PR-positive) are likely to respond to hormonal therapies, which block hormones from binding to these receptors.
  • Testing for hormone receptors is conducted using immunohistochemical staining, which highlights the presence of these receptors in cancer cells.

Human epidermal growth factor receptor 2 (HER2) Status:

  • The HER2 gene produces proteins that regulate cell growth. In about 20% of breast cancers, this gene is overexpressed, leading to aggressive cancer growth. HER2-positive cancers may grow and spread more quickly than HER2-negative cancers
  • HER2 status is assessed using tests such as ImmunoHistoChemistry (IHC) and Fluorescence In Situ Hybridization (FISH), providing scores that guide treatment plans.

Cancer Grade:

  • Cancer grade refers to how much the cancer cells differ from normal cells, indicating how quickly the cancer is likely to grow and spread.
  • The Nottingham grading system evaluates three factors: tubule formation, nuclear pleomorphism, and mitotic rate. Scores from these assessments determine if the cancer is low grade (1), moderate grade (2), or high grade (3).
  • Lower-grade cancers tend to grow slowly and have a better prognosis, while higher-grade cancers may require more aggressive treatment due to their rapid growth.

These factors collectively inform the breast cancer stage, contributing to a comprehensive understanding of the disease. They are fundamental in selecting appropriate therapies, understanding cancer behavior, and tailoring individual treatment plans. Understanding and accurately assessing ER, PR, HER2 status, and cancer grade are essential for optimizing breast cancer management and improving patient outcomes.

References:

1. Breastcancer.org. Breast Cancer Stages. Available at: https://www.breastcancer.org/pathology-report/breast-cancer-stages.
2. Davis C Teichgraeber et.al. Breast Cancer Staging: Updates in the AJCC Cancer Staging Manual, 8th Edition, and Current Challenges for Radiologists, From the AJR Special Series on Cancer Staging. AJR Am J Roentgenol. 2021 Aug;217(2):278-290. doi: 10.2214/AJR.20.25223.