Staging is done to detect or staging gives an idea about the extent to which the disease has spread and affected the body. The staging defines the tumor or the size of the lump, affected lymph nodes, invasive nature and its spread to other parts. Based on these four parameters the stage of cancer growth is determined and specified for treatment plan. The breast cancer staging is usually described in roman numerals from 0 to IV. 0 is the starting of the scale which describes initial stage cancer and IV describes the advanced stages cancer. Staging involves a lot of diagnostic testing. Apart from the above mentioned parameters, the doctor may also use terms like local, regional and distant to describe the cancer stage. Local would imply that the cancer is restricted to the breast and has not spread outside. Regional means that lymph nodes present in the arm pit are affected. Distant would mean that the cancer has spread to other parts of the body.
Staging is an imperative part of the treatment of breast cancer as it helps in determining the outcome of the disease and as such defining the treatment regime and the plan. Staging gives a standard nomenclature to the disease. As a multi-modal intervention is required to treat cancer, this standard nomenclature provides a relative term which can be understood by all involved.
Also a very popular method of staging called TNM staging is used to understand the advancement of cancer in a patient. It is described in next section.
It is used to describe early stage cancer in which there is no sign or visible proof of the tumor (benign or malignant) cells to have spread out of the breast. Stage 0 cancer means that the cancer is a non-invasive breast cancer, and has not yet affected other healthy and normal tissue outside of the affected breast.
Stage I is the next stage cancer which means the tumor is no longer non – invasive but has acquired an invasive nature and the tumor cells are attacking normal tissue near to the breast. This stage is further subdivided into two categories: stage IA and stage IB
Stage IA describes invasive breast cancer which has a 2 cm growth tumor and the cancer is still restricted inside the affected breast with no involvement of lymph nodes.
Stage IB describes the cancer in which the tumor cells are outside the breast in the surrounding lymph nodes. These tumor cells are in small groups of 0.2 mm to 2mm in size. Also stage IB classification can be used if a similar tumor is present in the breast in addition to the tumors in lymph nodes. This attack of cancer cells in stage I can also be a microscopic invasion if these tumor cells do not measure > than 1mm in size.
Stage II of breast cancer is further subdivided into stage IIA and stage IIB. In stage IIA there is no evidence of cancerous cells in the breast but one to three lymph nodes may have a tumor growth of >2mm. these lymph nodes may be in surrounding area of the breast like the underarms or the breastbone. A stage IIA cancer may also describe a cancerous growth of 2cm or smaller in the axillary lymph node, a growth which though has not invaded the axillary lymph node but is more than 2 cm and less than 5 cm will also be classified in stage IIA breast cancer. Stage IIB is used to describe invasive breast cancer in which the tumor in the breast is also present along with tumor in the lymph nodes. The tumor can be from 2cm to 5 cm in size and the lymph node cancer cells may be 0.2 mm to 2mm in size. Also if this (2cm – 5cm sized) tumor has invaded one to three axillary lymph nodes or breastbone lymph nodes then it is again classified as stage IIB cancer. Stage II B cancer is also used to describe a cancerous growth which though has not invaded the axillary lymph nodes but measures larger than 5cm.
Stage III breast cancer is sub-divided in three categories: IIIA, IIIB and IIIC. IIIA stage is used to describe the cancer which may or may not be present in the breast but has spread to 4 to 9 axillary lymph nodes and breast bone lymph nodes. Also when the cancerous growth is larger than 5 cm with the cancerous growths of 0.2 mm – 2 mm size invading the lymph nodes, it is termed as IIIA type breast cancer. A growth of 5 cm with invasion in 1 to 3 breastbone and axillary lymph nodes is also called IIIA type cancer. Invasive breast cancer of stage IIIB is when the cancerous growth has attacked the wall of the chest with the breast skin resulting in a sore or a boil or a swelling combined with a spread to 9 axilliary lymph nodes or the breastbone lymph nodes. Stage IIIB also classifies inflammatory breast cancer. This cancer is presented with symptoms like redness in breast skin with swelling of the breast. The breast may also feel warm. This is when the cancer has advanced to lymph nodes and the cancerous cells have stretched to the skin. Stage IIIC is used for cancerous growth which has spread and affected the chest wall, breast skin, invaded at-least 10 or more axillary lymph nodes or affected lymph nodes near breast bone, collar bone. The tumor in the breast may be present or not but irrespective of that the extent of damage described above classifies a tumor in stage IIIC breast cancer.
Stage IV is the most advanced stage of breast cancer and often the term ‘metastatic” is also used to describe this stage. This the stage when the tumor is no longer contained in and around the breast but has invaded and spread to other parts of the anatomy.
The T parameter is explained by numbers 1 to 4, indicating the size of the tumor and its invasion to surrounding cells. Number 4 indicates highest size and spread to near vicinity cells of the cancerous growth. In T parameter, TX implies no findings for tumor positivity or it cannot be measured.T0 signifies no detection of primary tumor. Tis describe cancerous growth which is limited or restricted to the primary site inside the breast.
The N parameter describes the number of lymph nodes affected, the size of affected cells in the lymph nodes again numbers are used to categorize further with a smaller number reflecting a less severe condition. The N category have further classification like NX meaning again no finding or evidence of cancer in nearby lymph nodes, N0 describes no detection of cancerous growth in lymph nodes.
The M parameter indicates a tumor growth away from the original affected area and the spread in the body. Again numbers indicate the location for example a M0 would be used to describe a condition with zero metastases other that growth site. This parameter describes in more detail the cancerous growth as the outcome and the treatment plan were vary in distant metastases positive cases. Further categorizing MX indicates no evidence of metastasis, M0 describes that there is no metastatis.