Ductal carcinoma refers to breast cancer that begins in the milk ducts. Determining the stage of ductal carcinoma is important for prognosis and guiding treatment. The stage refers to how far the cancer has spread from the original tumor.
Staging of Ductal Carcinoma
There are a few different staging systems used for breast cancer:
- TNM staging
- Number staging (stage 0-IV)
- Tumor grade (GX, G1-G3)
The TNM staging system is the most commonly used. It takes into account:
- T: Size of the original (primary) tumor
- N: Spread to nearby lymph nodes
- M: Metastasis to distant sites
T – Size of the Primary Tumor
The T category describes the original tumor:
- TX: Tumor size cannot be assessed
- T0: No evidence of primary tumor
- Tis: Carcinoma in situ (DCIS, LCIS)
- T1: Tumor 2 cm or less across
- T2: Tumor is 2-5 cm across
- T3: Tumor is more than 5 cm across
- T4: Tumor any size with extension to chest wall or skin
N – Spread to Lymph Nodes
The N category indicates spread of cancer to regional lymph nodes:
- NX: Lymph node status cannot be assessed
- N0: No regional lymph node metastasis
- N1: Metastasis to 1-3 axillary lymph nodes
- N2: Metastasis to 4-9 axillary lymph nodes
- N3: Metastasis to 10 or more axillary lymph nodes
M – Distant Metastasis
The M category indicates whether the cancer has metastasized to distant organs:
- M0: No distant metastasis
- M1: Distant metastasis present
Stage Grouping
The T, N, and M results are combined to determine the overall cancer stage (Stage 0 through Stage IV):
| Stage | T | N | M |
|---|---|---|---|
| 0 | Tis | N0 | M0 |
| IA | T1 | N0 | M0 |
| IB | T0 or T1 | N1mi | M0 |
| IIA | T0 or T1 | N1 | M0 |
| IIB | T2 | N0 or N1 | M0 |
| IIIA | T0 to T2 | N2 | M0 |
| IIIB | T3 | N1 or N2 | M0 |
| IIIC | Any T | N3 | M0 |
| IV | Any T | Any N | M1 |
As the stage increases from 0 to IV, the cancer is more advanced and has a worse prognosis.
Stage 0
Stage 0 breast cancer is also called carcinoma in situ. This means the cancer cells are confined to the milk ducts (ductal carcinoma in situ, DCIS) or lobules (lobular carcinoma in situ, LCIS) and have not spread into surrounding breast tissue.
Stage 0 cancers are non-invasive pre-cancers that have not become true cancers. However, they can increase the risk of developing an invasive breast cancer later on.
Stage I
Stage I breast cancers are still relatively small and either have not spread to lymph nodes (IA) or have micrometastases in 1-3 axillary lymph nodes (IB).
The main tumor is 2 cm or smaller across. Women with stage I breast cancers have an excellent prognosis after treatment.
Stage II
Stage II breast cancers are larger or have spread to a few nearby lymph nodes.
Stage IIA cancers are no larger than 2 cm across with spread to 1-3 axillary lymph nodes. They may also be 2-5 cm across, but haven’t spread to lymph nodes (IIB).
5 year survival rates are about 70-80% for stage II breast cancers.
Stage III
Stage III breast cancers are more advanced local-regional cancers. They are larger cancers (more than 5 cm across) that have spread to 4-9 axillary lymph nodes (IIIA).
They can also be any size and have spread to 10 or more axillary lymph nodes or nearby tissues like the skin or chest wall (IIIB).
Inflammatory breast cancer is usually at least stage IIIB. The cancer cells block lymph vessels in the skin causing redness, warmth and swelling.
Stage IIIC breast cancer describes any cancer, regardless of size, that has spread to 10 or more axillary lymph nodes or has spread to lymph nodes near the collarbone or under the sternum.
Stage IV
Stage IV breast cancers have metastasized, or spread, to distant sites like the bones, liver, lungs or brain.
Stage IV is considered advanced or metastatic breast cancer. While it can be treated, it isn’t considered curable.
The 5-year survival rate for metastatic breast cancer is about 27%. However, there are often many effective treatments available to keep the cancer controlled for years.
Tumor Grade
In addition to the TNM stage, the tumor grade is also used to characterize breast cancers. The grade is based on how abnormal the cancer cells look under the microscope.
Higher grade tumors tend to grow and spread faster than lower grade tumors. Tumor grade is classified as:
- GX: Grade cannot be determined
- G1: Well-differentiated (low grade)
- G2: Moderately differentiated (intermediate grade)
- G3: Poorly differentiated (high grade)
Prognosis by Stage
In general, the prognosis and survival rates go down as the stage increases. However, many factors determine an individual’s prognosis including age, tumor grade, hormone receptor status, and other features.
Here are some general survival statistics by breast cancer stage:
- Stage 0 – Nearly 100% 5-year survival
- Stage I – 100% 5-year survival
- Stage II – 93% 5-year survival
- Stage III – 72% 5-year survival
- Stage IV – 27% 5-year survival
However, these numbers can vary significantly based on the specific tumor characteristics and response to treatment.
Conclusion
Determining the stage of ductal carcinoma helps estimate prognosis and direct treatment options. Lower stage cancers are small localized tumors that often have excellent cure rates.
Higher stage cancers have spread to lymph nodes or metastasized to distant organs. They require more aggressive systemic treatments like chemotherapy, hormone therapy or targeted drugs.
While stage IV metastatic breast cancer isn’t considered curable, treatments can often control it for many years. Monitoring for recurrence and metastatic disease is important for all breast cancer survivors.