As defined by BreastCancer.org, breast cancer is an uncontrolled growth of breast cells.
How does cancer develop? This condition is a result of abnormal changes in the genes. These genes are the ones that control the growth of each cell in addition to keeping them healthy. Under normal conditions, as some cells grow and divide, others will die off. But with cancer, the abnormal cells start growing at such an unusually rapid pace that a tumor soon forms.
Some tumors are benign, while others are malignant or cancerous. With breast cancer, this malignancy more than likely starts in the milk-producing glands – the ducts from where milk flows to the nipple. If left unchecked, cancer cells of the breast can invade healthy breast tissue or even to lymph nodes located underarm. And as BreastCancer.org states, once it enters the lymph nodes, it is very easy to spread to other parts of the body. As regards to what parts of the body are affected or how far it has spread, scientists refer to this as stages of breast cancer.
The stages of breast cancer are listed below, as indicated by Cancer.gov:
Stage 0 (carcinoma in situ)
There are 2 types of breast carcinoma in situ:
Ductal carcinoma in situ (DCIS) is a noninvasive condition in which abnormal cells are found in the lining of a breast duct. The abnormal cells have not spread outside the duct to other tissues in the breast. In some cases, DCIS may become invasive cancer and spread to other tissues, although it is not known at this time how to predict which lesions will become invasive.
Lobular carcinoma in situ (LCIS) is a condition in which abnormal cells are found in the lobules of the breast. This condition seldom becomes invasive cancer; however, having lobular carcinoma in situ in one breast increases the risk of developing breast cancer in either breast.
In stage I, cancer has formed. The tumor is two centimeters or smaller and has not spread outside the breast.
In stage IIA:
No tumor is found in the breast, but cancer is found in the axillary lymph nodes (the lymph nodes under the arm)