According to most sources, breast cancer is 'cancer of the breast tissue'. Not very helpful. But digging a little deeper makes the answer clear. Cancer is a malignant growth or tumor caused by abnormal or uncontrolled cell division. Normal cells become misshapen and grow too rapidly. The result is a mass or lump that continues to grow and may spread.

Not all lumps are cancerous. Most are benign. They reach a certain size and level off. They may be soft and fluid filled, like cysts. Or they may be firm like fibroadenomas, which also are benign since they don't grow and spread. Or, they may simply be scar tissue or hardened fat.

But a true cancer in breast tissues is malignant and serious. Nearly 90% are a type known as ductal carcinoma (sometimes called DCIS, ductal carcinoma in situ). Somewhat less than 10% of the rest are lobular carcinomas (LCIS). In both cases lumps may appear as a thickening in some part of the breast, or even in the armpit. Lymph nodes are located there and sometimes play a role in the development of the disease.

The American College of Physicians recommends self-examination beginning around age 20 and regular mammograms after age 40.

Though one shouldn't become alarmed at every possible change, an alteration of the size or shape of the breast after maturity is one sign to look for. Fluid may leak from the nipple that doesn't resemble milk. In cases of cancer, it's typically a type of pus, indicating infection.

The nipple or areola (the darkened skin around the nipple) can also change size or shape.

Breast cancer develops through identifiable stages which mark out the progression of the disease.

Stage 0 is when the condition first occurs, Stage I exists when the tumor is less than 2cm thick and hasn't spread. By Stage II the tumor is between 2-5cm thick and there may be other areas affected. Once the disease reaches Stage III it has penetrated the chest wall. By that level, treatment becomes very difficult and the survival rate is correspondingly low.

Stage IV is the most serious. At this point the cancer has, as it's called, metastasized. That means the cancer has spread and that it has formed secondary tumors which resemble the initial growth. Such cancers are very often fatal.

Because of these stages, and the increasing health consequences at each level, seeking diagnosis and treatment early is imperative. A simple lumpectomy may well cure the condition completely. If it progresses to the point that chemotherapy or radiation treatments are called for, the odds of recover are much lower and the cure is often as bad as the disease.

Fortunately, enormous progress has been made over the past 40 years. The latest equipment allows for much better diagnosis. Treatments have evolved to make the cure less painful and more certain.

Though any stage is a concern, there is an over 95% five-year survival rate for those that are identified and treated by Stage I. Improve your odds by careful monitoring and seeking early diagnosis.