When your doctor mentions the stage of breast cancer, he indicates the state or the condition or the severity of the breast cancer.

The breast cancer stage also indicates to what extent cancer has progressed or how much it has spread. There are different stages of breast cancer and each stage has a story to tell about the condition of cancer.

Breast cancer staging has been evolved to give the doctor an idea of the cancer he is dealing with.

Staging can be done either before or after a patient undergoes surgery. Diagnostic tests help to determine cancer’s stage.

The staging of breast cancer is very important for your oncologist or cancer specialist because

  • It helps to determine the type of treatment to be given for that particular cancer patient.
  • It helps to evaluate the prognosis and survival due to the treatment.
  • Staging breast cancer helps to bring about a global benefit in collecting information on breast cancer and its statistics for better research.

The most widely used system in the U.S. is the American Joint Committee on Cancer (AJCC) TNM system.

In 2018, a new eighth edition of this staging system has been developed that includes results of pathological testing for certain biomarkers, such as HER2 protein, estrogen receptor (ER), progesterone (PR), and also the results of gene expression assays.

TNM breast cancer staging

  • T stands for Tumor,
  • N stands for the Node of the lymphatic system and
  • M stands for metastasis (spread of cancer).

TNM staging of breast cancer is usually used to stage solid malignant tumors. Most of the tumors are classified by this system but some like brain tumors are not.

TNM staging of cancer was developed by a non-governmental body called UICC or International Union Against Cancer with the purpose to bring about a global consensus to stage cancers and access their spread.

This purpose has been achieved and TNM is globally used. This also helped to bring about a coordinated global effort in cancer research. The UICC cancer staging has the same definitions as the AJCC cancer staging (American Joint Committee on Cancer).

Numbers are suffixed after T, N, and M to indicate the progress of cancer. An ‘X’ suffixed after T or N or M simply means the cancer has yet to be assessed or evaluated and therefore no staging has been done yet.

  • The T staging informs of the size of the tumor. Numbers 1 to 4 are suffixed after ‘T’ to indicate the size of the tumor. A “T1” will mean a smaller-sized tumor while a “T4” will indicate a larger-sized tumor.
  • The N describes the lymph node involvement if any. 0 to 3 are suffixed after ‘N’ to indicate the extent of the spread of malignancy to the lymph nodes. N-0 will indicate that there has been no spread or metastasis of malignancy to the lymph node. N1 will mean spread to the local regional lymph node. N3 will mean more involvement to the distal and more numerous lymph nodes. N2 gives the metastasis involvement between N1 and N3.
  • The M describes the spread of breast cancer to distal organs. 0 and 1 are used after M to indicate metastasis to other distant organs. M-0 means no metastasis and M1 will indicate that the malignancy has spread from the primary site to distant organs. This is the final stage of breast cancer.

For example, a T1N2M0 tumor is a small primary tumor with two lymph nodes showing signs of cancer and no sign of metastasis. Once the TNM staging is done, this information is used to determine stage grouping.

Grouping breast cancer stages

In this system, the stage of breast cancer is identified using roman numbers O to IV – higher the number the more progressive the cancer is. The 4 cancer stages can also give an idea to the doctor of the survival chances of the cancer patient.

Breast cancer of stage O

This stage means a localized early stage of cancer, wherein cancer cells have begun to form, they are localized to one tissue or part, have not invaded to the neighboring tissues, and possibly the tumor is yet to form. This is used to describe ductal carcinoma in situ and breast cancer is almost always curable when detected at this stage.

Breast Cancer Stage 1

This stage will indicate that the breast cancer is still small and contained within the breast. The tumor is no more than 2 cms across with no involvement of lymph nodes.

Breast Cancer Stage II

In stage II, the breast cancer tumor is bigger than stage 1 and measures between 2cms to 5 cms or the lymph nodes in the armpit are involved or both. The tumor has not invaded the neighboring tissues.

Breast Cancer Stage III

Stage III is divided into IIIA, IIIB, and IIIC. The tumor is larger than stage II cancer and has spread to the local and distal lymph nodes.

  • Stage IIIA. The tumor is not more than 5 cms across. The lymph nodes in the armpit are involved and are attached to each other or to the neighboring structures. The lymph nodes behind the breast bone may or may not be involved. The lymph nodes in the armpit are involved and may be attached to each other or to the neighboring structures.
  • Stage IIIB. This stage describes invasive breast cancer. The tumor may be of any size and has invaded the skin of the breast or the chest wall. There may be spread to lymph nodes in the armpit. The lymph nodes in the armpit are involved and may be attached to each other or to the neighboring structures. The cancer may have spread to lymph nodes under the breastbone. Inflammatory breast cancer, a rare breast cancer, belongs to this stage. The breast is red and swollen due to the blockage of lymphatic vessels by the invading cancer cells.
  • Stage IIIC. The tumor is of any size and has spread to lymph nodes in the armpit and the breastbone. It has spread to the lymph nodes above or below the collarbone (clavicle).

Breast Cancer Stage IV

This stage indicates that the breast cancer has spread or metastasized to the distal organs such as the liver or bones or lungs. This is the last stage of breast cancer. Breast cancer of stage 4 is very advanced and aggressive. It renders surgery and radiation ineffective. Systemic therapy remains the choice of treatment. Survival rates are very dismal. The 5-year survival rate for breast cancer of this stage is 16% to 20%.

Breast cancer survival by stages

Survival rate for breast cancer stages

  • Stage 0 and 1 — 5-year survival rate is 100%
  • Stage 2  — 5-yea survival rate is 93%
  • Stage 3 — 72%
  • Stage 4 — 22%

How is the breast cancer stage determined?

The 4 breast cancer stages mentioned above are arrived at after careful examination of the cancer patient. Just signs and symptoms of breast cancer are not enough to confirm the stage of cancer. A thorough investigation is necessary which includes:

  • Clinical examination. After a thorough physical examination of the patient, the doctor determines the location and size of the tumor and feels for any enlarged lymph nodes in the axilla or above the collar bone.
  • Pathological investigations of blood, stools, urine, and body fluids look for any increased or decreased levels that may indicate malignancy. These include testing for certain biomarkers, including the HER2 protein, estrogen receptor (ER), and progesterone (PR), and the results of gene expression assays,
  • Radiological studies such as X-rays, CT scans, MRIs, and PET scans will show the location and size of the malignant tumor and also its spread if any to the liver, lungs, and brain. Bone scans are done to rule out the spread of cancer to the bones.
  • Surgical investigation such as a surgical biopsy is performed and examined in pathology for any malignant signs. A surgical report prepared during surgery mentions, confirms, or reports any changes in the size of the tumor and on its spread to neighboring lymph nodes.