Breast cancer cells start out as normal body cells, but they begin to grow out of control because of an abnormal gene. The immune system plays a major role in limiting the development of these abnormalities, often before cancer has a chance to grow. This gets rid of many cancerous cells before they can do any harm. Damaged, pre-cancerous cells may be a constant presence, but an ever-alert immune system takes them out and protects us from many assaults of cancer that never get beyond the very earliest stage.
When the immune system fails
Occasionally, though, even though cells are changing from normal to abnormal, they may still appear to be normal. Their outer appearance (proteins and other molecules on their surface) may look unchanged, even though profound changes may be happening on the inside. In this way, these abnormal cells manage to escape attack by the immune system and grow and multiply without triggering an immune response. This is how it's possible for a tumor to form, even when your immune system is working normally. Eventually, however, the tumor becomes so altered and threatening that it can no longer hide its malignant character. The immune system is no longer fooled into recognizing these cells as normal, and launches its attack.
The attack may succeed, or it may come too late: the tumor may be beyond the power of the immune system by itself. The immune system may need help—bold measures such as:
- immune growth factors—medicines that stimulate the production of new immune cells;
- antibody medications—special antibodies made in a laboratory, designed to target a specific antigen on a cancer cell;
- vaccines—agents that stimulate your immune system to fight back, giving it a wake-up call to action; and
- non-immune-system intervention, such as: