Stages of Breast Cancer Development

Stages of Breast Cancer Development

Breast cancer progresses through several stages, which are defined based on the tumor's location, its size and growth, and whether it has spread to other parts of the body. It should be noted that determining the stage of cancer requires appropriate diagnostic tests, and therefore, a definitive staging can only be confirmed after all test results are available. It is crucial to emphasize that accurate staging plays a vital role in selecting the most suitable treatment plan for the patient and predicting the disease’s future course and chances of recovery.^[1] The Tumor-Node-Metastasis (TNM) staging system is the most widely used method for determining breast cancer stages. This system represents the seventh edition of the breast cancer staging guidelines issued by the American Joint Committee on Cancer (AJCC). It relies on both clinical and pathological features of breast cancer, as outlined below:^[2][3]

• Pathological aspects: Also referred to as surgical staging, this is determined by examining tissue samples removed during surgery aimed at completely removing the tumor. In this case, surgery is performed initially to control the tumor, meaning treatment begins before final staging is established.
• Clinical aspects: Clinical staging is used when surgery is not feasible. This determination depends on various factors, including physical examination findings, imaging tests, and biopsy samples taken from the patient. Accurate clinical staging helps guide the development of an appropriate treatment plan. However, in some cases, the cancer may have spread further than indicated by clinical staging, making it difficult to predict the disease's progression with precision compared to pathological staging.

The TNM system classifies breast cancer into five stages, starting from stage zero (0), followed by stages 1 to 4. Stages 1 through 4 are typically denoted using Roman numerals—I, II, III, and IV. Generally, the higher the number, the more advanced and widespread the cancer. Stage zero (0) indicates cancer confined to its original site without any spread, while stage IV represents the most extensive spread compared to other stages. Additionally, specific symbols are used to describe key characteristics of the cancer, which are explained below:^[2][3]

• Letter T: Indicates the tumor’s size and extent of invasion into surrounding tissues.
• Letter N: Reflects the spread of cancer to nearby lymph nodes.
• Letter M: Indicates whether the tumor has spread to distant sites beyond the breast, such as the liver or lungs.
• ER symbol: Indicates whether the cancer possesses estrogen receptors (ER).
• PR symbol: Indicates whether the cancer has progesterone receptors (PR).
• Grade letter G: Refers to the cancer grade, reflecting how closely the cancer cells resemble normal breast cells.
• HER2 symbol: This marker indicates whether the gene responsible for producing Human Epidermal Growth Factor Receptor 2 (HER2) proteins has undergone mutation. These proteins normally exist on the surface of breast cells. A genetic mutation leads to increased gene copies, resulting in overproduction of HER2 proteins, which triggers uncontrolled cell growth and division in breast tissue. A positive result is labeled as HER2-positive; a negative result is labeled as HER2-negative.^[4]

Stage 0

Stage zero, also known as carcinoma in situ, refers to non-invasive breast cancer. There are three main types of this condition, described as follows:^[5]

• Ductal Carcinoma In Situ (DCIS): This is a non-invasive form of cancer where abnormal cells are found within the lining of the milk ducts in the breast. DCIS is considered an early stage, with high potential for recovery if treated appropriately. If left untreated or undetected, it may progress to invade surrounding breast tissue.
• Lobular Carcinoma In Situ (LCIS): This involves abnormal cell growth inside the lobules of the breast without spreading to surrounding tissues. LCIS is not classified as cancer itself but increases the risk of developing invasive breast cancer in the future.
• Paget’s Disease of the Nipple: A rare type of breast cancer affecting the skin of the nipple and the surrounding areola. Most patients with this condition have one or more tumors within the same breast, typically originating as DCIS or invasive breast cancer.^[6]

Stage 1

In stage 1 breast cancer, the tumor measures less than 2 centimeters and has not spread to any other part of the body, including lymph nodes.^[7] It is important to note that cancer cells at this stage are invasive, meaning they have penetrated surrounding normal breast tissue. Stage 1 is divided into two sub-stages: 1A and 1B. Below is a description of each:

• Stage 1A: The tumor is no larger than 2 cm, has not spread outside the breast, and has not reached the lymph nodes.
• Stage 1B: This stage includes either of the following conditions: no detectable tumor in the breast, but small clusters of cancer cells (0.2–2 mm) are present in nearby lymph nodes; or a tumor in the breast measuring no more than 2 cm, along with cancer cells in nearby lymph nodes (also 0.2–2 mm).

Stage 1A is assigned when the cancer is positive for estrogen or progesterone receptors. During stage 1, microscopic invasion may occur, where cancer cells begin to infiltrate tissues outside the milk ducts or lobules but remain under 1 mm in size.^[8]

Stage 2

In stage 2 breast cancer, the tumor ranges from 2 to 5 centimeters in size and affects lymph nodes in one or both armpits. There is no evidence of distant spread to other areas of the body. Stage 2 is subdivided into two categories: 2A and 2B. Details for each are provided below:^[9][10]

• Stage 2A: The cancer is invasive and characterized by the following:

• No visible tumor in the breast, but cancerous masses exceeding 2 cm are found in up to three lymph nodes in the armpit area or near the sternum (breastbone).
• A tumor in the breast measuring no more than 2 cm, with involvement of lymph nodes in the armpit.
• A tumor between 2 and 5 cm in size, but without spread to axillary lymph nodes.
• Stage 2B: The cancer is invasive and characterized by the following:

• A tumor between 2 and 5 cm in size with small groups of cancer cells (0.2–2 mm) in the lymph nodes.
• A tumor between 2 and 5 cm in size, with cancer cells spreading to up to three axillary lymph nodes or those near the sternum.
• A tumor larger than 5 cm in the breast, but without spread to axillary lymph nodes.

Stage 3

Stage 3 breast cancer is also referred to as locally advanced breast cancer. The tumor size ranges from 2 to 5 cm, and the cancer has spread to nearby tissues such as the skin covering the breast, regional lymph nodes, or even the chest wall. Lymph nodes in the armpit are also affected. There is no sign of distant metastasis. Stage 3 is further divided into three sub-stages: 3A, 3B, and 3C. Below is a detailed breakdown:

• Stage 3A: One of the following applies:

• No visible tumor in the breast, or any tumor size, along with cancer detected in four to nine axillary lymph nodes or those near the sternum.
• A tumor larger than 5 cm in the breast, accompanied by small clusters of cancer cells in the lymph nodes.
• A tumor larger than 5 cm in the breast with cancer cells spreading to up to three axillary lymph nodes or those near the sternum.
• Stage 3B: The cancer has spread to the skin of the breast, potentially leading to inflammatory breast cancer, or to the chest wall, which includes ribs, muscles, skin, and connective tissues protecting the lungs. In this stage, cancer cells may involve up to nine axillary or sternal lymph nodes. This stage often causes skin ulcers or swelling.
• Stage 3C: No tumor may be present, or it may be of any size, but cancer is evident in the breast skin causing swelling or ulcers, and has invaded the chest wall. Additionally, it has spread to one or more of the following structures:

• Ten or more axillary lymph nodes.
• Lymph nodes located above or below the clavicle (collarbone).
• Both axillary lymph nodes and those near the sternum.

Stage 4

Stage 4 breast cancer is invasive or metastatic, meaning the tumor has spread beyond its original site. Cancer cells in this stage may reach distant organs and remote lymph nodes. The most common sites of metastasis include the brain, liver, lungs, bones, and distant lymph nodes.^[12][8]

Overview of Breast Cancer

Breast cancer refers to cancers originating in breast tissue, usually forming a tumor. There are three main types of breast tumors: benign (non-cancerous), in situ (confined to original location), and invasive (spreading beyond the original site). Most tumors developing in breast tissue are benign, meaning non-cancerous. In situ tumors are limited to the milk ducts or lobules within the breast. Invasive tumors are the most dangerous form, as they spread to other parts of the body. According to the World Cancer Research Fund International, breast cancer is the most common cancer among women and the second most common overall. Fortunately, mortality rates due to breast cancer have declined in recent years, largely due to early detection. Prompt treatment after diagnosis significantly improves outcomes. Early detection through regular mammograms—a type of breast X-ray—plays a critical role in identifying breast cancer at an early stage.^[13][14]

To learn more about breast cancer, read the following article: (What Is Breast Cancer).

Podcast: Prevention After Recovery from Breast Cancer

Recovery from cancer is not the end of the journey—it marks the beginning of a new chapter requiring awareness, support, and resilience

In this episode of Meet the Pioneers, in collaboration with Novartis, we explore the challenges faced by women recovering from breast cancer,

with Dr. Fathi Zeribi and Dr. Hossam Mraishi, discussing strategies to overcome these challenges through medical follow-up, psychological support, and social care.

#BeyondOctober

References

1. ↑ "Breast Cancer: Stages", cancer.net, Retrieved 24-2-2020. Edited.
2. ^ ^{a b} "Stages of breast cancer", cancer.ca, Retrieved 24-2-2020. Edited.
3. ^ ^{a b} "Breast Cancer Stages", cancer.org,20-9-2019, Retrieved 25-2-2020. Edited.
4. ↑ "HER2 Status", medlineplus.gov, Retrieved 25-2-2020. Edited.
5. ↑ "Stages 0 & 1", nationalbreastcancer.org, Retrieved 25-2-2020. Edited.
6. ↑ "Paget Disease of the Breast", cancer.gov, Retrieved 13-04-2020. Edited.
7. ↑ "Breast Cancer", my.clevelandclinic.org,31-12-2018, Retrieved 25-2-2020. Edited.
8. ^ ^{a b c} "Breast Cancer Stages", breastcancer.org,23-7-2019, Retrieved 25-2-2020. Edited.
9. ^ ^{a b} "Breast cancer in women", nhs.uk,28-10-2019, Retrieved 25-2-2020. Edited.
10. ↑ Bethany Cadman (15-8-2018), "What happens at each stage of breast cancer?"، medicalnewstoday.com, Retrieved 25-2-2020. Edited.
11. ↑ " breast cancer ", cancerresearchuk.org,4-10-2017, Retrieved 26-2-2020. Edited.
12. ↑ Carol DerSarkissian (6-11-2019), "What Are the Stages of Breast Cancer?"، webmd.com, Retrieved 25-2-2020. Edited.
13. ↑ "Breast Cancer", familydoctor.org, Retrieved 24-2-2020. Edited.
14. ↑ "Breast cancer statistics", wcrf.org, Retrieved 14-03-2020. Edited.