Breast cancer is a type of cancer where cells in the breast tissue divide and grow out of control. This can be happening before you notice anything is wrong. Some cancer tumors grow more quickly than others.
There are different types of breast cancer. Some cancers start in the milk ducts, but haven’t spread into the tissue around the milk ducts. This is called ductal carcinoma in situ (or DCIS). This is how most breast cancers start. There are other cancers that spread from the milk ducts into the breast tissue. These are called invasive carcinomas. When cancer has spread from the breast into other parts of the body, this is called metastasis.
Not all breast problems are breast cancer. These may be called benign (not cancer). One example is a cyst. There are other kinds of benign problems as well. You will need to be checked by your doctor and maybe have some tests done to find out what is happening.
We don’t know exactly what causes breast cancer. Basically it is caused by a change in your genes (which make up everything in your body) called a mutation. Most gene mutations that occur with breast cancer are spontaneous, meaning they just happen and are not inherited (or passed down in families). What causes this change mutation to happen is what we still don’t know. However, there are things called risk factors that we do know about that could increase your chance of getting breast cancer.