The term "Level 1" is not used in the context of breast cancer staging. However, "Stage 1" breast cancer is well-defined. Here are the details:

Stage 1 Breast Cancer
- Definition: The earliest form of invasive breast cancer.
- Substages:
- Stage 1A: Tumor up to 2 centimeters with no cancer cells outside the breast.
- Show Full Answer

The term "Level 1" is not used in the context of breast cancer staging. However, "Stage 1" breast cancer is well-defined. Here are the details:

Stage 1 Breast Cancer:
- Definition: The earliest form of invasive breast cancer.
- Substages:
- Stage 1A: Tumor up to 2 centimeters with no cancer cells outside the breast.
- Stage 1B: Either no tumor in the breast but small groups of cancer cells (0.2-2 millimeters) in lymph nodes, or a tumor in the breast and small groups of cancer cells in lymph nodes.
- Prognosis: Very favorable with a five-year survival rate of 99%.

Key Points:
- Stage 1 is classified based on tumor size and lymph node involvement.
- Stage 1A and Stage 1B provide more specific details about the tumor and lymph nodes.

For more detailed information, you can refer to the source: [Stage 1 Breast Cancer: Treatment and Prognosis | MyBCTeam](https://www.mybcteam.com/resources/stage-1-brea...).

 This AI-generated response comes from MyBCTeam and other selected sources. It is not a substitute for medical advice. Always ask your doctor about specific health concerns.

Stage 1 Breast Cancer: Treatment and Prognosis | MyBCTeam

Breast Cancer: Stage and Grade | MyBCTeam