What are the different stages of breast cancer?

Breast cancer staging is a process used to describe the extent of the cancer within the body. Staging helps determine the appropriate treatment options and prognosis. The staging system commonly used for breast cancer is the TNM system, which evaluates the tumor size (T), lymph node involvement (N), and the presence of distant metastasis (M). Based on these factors, breast cancer is categorized into several stages, typically ranging from 0 to IV. Here's an overview:

Stage 0 (Carcinoma in situ): At this stage, the cancerous cells are confined to the ducts or lobules of the breast and have not invaded nearby tissue. It is considered non-invasive breast cancer. Stage 0 is further divided into two subtypes:

Ductal Carcinoma In Situ (DCIS): Cancer cells are found in the lining of the breast ducts.

Lobular Carcinoma In Situ (LCIS): Abnormal cells are found in the lobules of the breast, but they have not spread outside the lobules.

Stage I: Cancer is small and localized, typically measuring less than 2 centimeters (cm) in size. It has not spread to nearby lymph nodes or distant sites.

Stage II: Stage II breast cancer is divided into two subcategories based on tumor size and lymph node involvement:

Stage IIA: The tumor measures between 2 and 5 cm, and either there is no lymph node involvement, or small clusters of cancer cells are found in nearby lymph nodes.

Stage IIB: The tumor is larger than 2 cm but less than 5 cm and has spread to 1-3 nearby lymph nodes, or the tumor is larger than 5 cm but has not spread to any lymph nodes.

Stage III: Stage III breast cancer is considered locally advanced cancer, meaning it has spread more extensively to nearby tissue and lymph nodes. It is further divided into:

Stage IIIA: Cancer may be any size and has spread to 4-9 nearby lymph nodes or has caused extensive local invasion into nearby tissues.

Stage IIIB: The tumor may be any size and may have spread to the chest wall or skin of the breast. It may also involve up to 9 nearby lymph nodes.

Stage IIIC: Cancer has spread to 10 or more nearby lymph nodes, or it has spread to lymph nodes near the collarbone or breastbone.

Stage IV (Metastatic Breast Cancer): At this stage, cancer has spread beyond the breast and nearby lymph nodes to other organs or distant sites in the body, such as the bones, liver, lungs, or brain.

It's important to note that within each stage, there can be variations in prognosis and treatment options based on individual factors such as hormone receptor status, HER2 status, and overall health. Treatment plans are tailored to each patient's specific circumstances in consultation with a multidisciplinary healthcare team.