Understanding the different stages of breast cancer is an important part of the diagnostic and treatment journey. From stage 0 (pre-cancerous cells) to stage IV (metastatic cancer), each stage presents a different set of challenges and treatment approaches. While the journey can feel overwhelming, advancements in early detection, personalised medicine, and therapies are making a significant difference in survival rates and quality of life for breast cancer patients.
In this blog post, we’ll break down the stages of breast cancer, what each stage means, and how it influences treatment plans.
What Are the Stages of Breast Cancer?
The stages of breast cancer are defined by how far the cancer has spread from its original location in the breast. The stages are usually numbered from 0 to IV, with higher numbers indicating more advanced cancer. Each stage considers factors like the size of the tumour, whether the cancer has spread to nearby lymph nodes, and if it has metastasized to other parts of the body. In the UK, the most common staging system is the TNM. You might also be told about the number system. Or your doctor may talk about early, locally advanced or secondary breast cancer.
The TNM staging system
The TNM staging system stands for Tumour, Node, Metastasis.
- T describes the size of the tumour (cancer)
- N describes whether the cancer has spread to the lymph nodes)
- M describes whether the cancer has spread beyond the lymph nodes to a different part of the body
The Number staging system
Stage 0: Carcinoma in Situ (CIS)
Carcinoma in situ refers to abnormal cells found in the lining of the breast duct or lobules, but these cells have not spread beyond these areas. The most common form of stage 0 breast cancer is ductal carcinoma in situ (DCIS).
At this stage, cancer cells have not yet invaded the surrounding tissues, and the prognosis is typically very good. However, it is considered a precursor to more invasive forms of breast cancer, so treatment is often necessary to prevent progression.
Stage I: Early-Stage Invasive Cancer
In stage I, breast cancer is still relatively small and localized. The tumour is generally no more than 2 cm (about the size of a small marble) in diameter, and the cancer has not spread beyond the breast tissue.
- Stage IA: The tumour is smaller than 2 cm, and there is no spread to the lymph nodes.
- Stage IB: Small clusters of cancer cells are found in the lymph nodes, but the tumour in the breast is also small (2 cm or less).
At this stage, treatment may involve surgery, possibly followed by radiation or chemotherapy, depending on the tumour’s characteristics.
Stage II: Larger Tumours or Limited Spread to Lymph Nodes
Stage II breast cancer is a bit more advanced. The tumour size may be larger than 2 cm, and the cancer may have spread to nearby lymph nodes under the arm (axillary lymph nodes). However, the cancer is still confined to the breast and nearby tissues.
- Stage IIA: The tumour is no larger than 5 cm but has not spread to the lymph nodes, or the tumour is smaller than 2 cm but cancer cells are found in the lymph nodes.
- Stage IIB: The tumour is between 2 and 5 cm and has spread to a small number of nearby lymph nodes, or the tumour is larger than 5 cm without lymph node involvement.
Treatment for stage II typically involves surgery to remove the tumour, followed by radiation, chemotherapy, or hormone therapy, depending on the cancer’s specific characteristics.
Stage III: Locally Advanced Cancer
At stage III, the cancer is considered locally advanced, meaning it has spread to nearby tissues, including lymph nodes, but has not yet spread to distant parts of the body. This stage can be further divided into three subtypes based on the extent of spread.
- Stage IIIA: The tumour may be larger than 5 cm or spread to several nearby lymph nodes, but the cancer has not reached the chest wall or skin.
- Stage IIIB: The cancer has spread to the chest wall or skin of the breast, causing swelling or ulceration.
- Stage IIIC: Cancer has spread to more lymph nodes (especially those above or below the collarbone), and may also affect other nearby tissues.
Treatment for stage III breast cancer is more intense and may involve a combination of surgery, chemotherapy, radiation therapy, and possibly targeted therapy or immunotherapy, depending on the tumour’s characteristics.
Stage IV: Metastatic Breast Cancer (Secondary breast cancer)
Stage IV, also known as metastatic breast cancer, represents the most advanced stage. In this stage, cancer cells have spread beyond the breast and nearby lymph nodes to other organs, such as the bones, lungs, liver, or brain.
At stage IV, breast cancer is considered to be a chronic condition, though treatment is still possible to manage symptoms and extend life. The goal of treatment for stage IV is typically to slow the spread of cancer and relieve symptoms, using systemic therapies like chemotherapy, hormone therapy, targeted therapies, and immunotherapies.
Factors That Affect Staging
The specific stage of breast cancer can depend on several factors:
- Tumour size: Larger tumours typically indicate a higher stage.
- Lymph node involvement: The more lymph nodes that are affected, the higher the stage.
- Cancer’s spread (metastasis): If cancer cells have spread to distant organs, the cancer is staged higher (Stage IV).
- Tumour grade and type: The type of breast cancer (e.g., invasive ductal carcinoma, invasive lobular carcinoma) and its grade (how abnormal the cells look) can also influence the treatment plan.
Importance of Staging
Staging plays a crucial role in determining the treatment approach and predicting the outcome of breast cancer. Early-stage breast cancer has a better prognosis and is more likely to be treated successfully with surgery, radiation, and/or chemotherapy. In contrast, later stages require more intensive treatment and may involve ongoing management for years.
Additionally, staging helps doctors determine the best treatment options, whether the cancer is likely to recur, and how to monitor for any signs of metastasis in the future.
