Breast cancer can best be described as a type of cancer where cells abnormally divide and grow in the breast tissue. The site where breast cancer originated can typically be found either in the mammary ducts or the lobules. Cancerous tumors usually grow very slowly; by the time a lump is detectable by self examination; it can already be as much as 10 years old. However, it is important to understand the difference between invasive breast cancer and carcinoma in situ. The following is an overview of the various types of carcinoma in situ as well as invasive breast cancer.

When abnormal cells are growing in either the mammary ducts or the lobules, but have not spread outside of that area it is called carcinoma in situ. The term “in situ” means “in place” which describes the nature of the disease. The sub-categories of these diseases are ductal carcinoma in situ (DCIS), and lobular carcinoma in situ (LCIS).

DCIS is a disease where abnormal cells begin growing in the hollow areas of the mammary ducts. These abnormal cells carry a strong resemblance to those of invasive cancer - DCIS can actually become invasive cancer if left untreated. It is because of this reason that it is very important to frequently perform self examinations.

When the abnormal cell growth occurs in the open spaces of the lobules it is called lobular carcinoma in situ (LCIS). This is different from DCIS because it is in a different area and the cells do not have the potential to grow into invasive cancer. However, it has been proven that women who have LCIS are at higher risk of having invasive cancer.

If these abnormal cells in the mammary ducts or the lobules spread outside of that area, the disease is reclassified as invasive cancer. Invasive cancer has the ability to spread outside the origin area and affect the surrounding breast tissue, lungs, liver, and bones. Early detection is imperative to ensure a more successful treatment probability. Success rates dramatically decline as cases progress without treatment.

When a woman finds a lump it is very important to have it checked out; the odds of that lump being invasive cancer is about 20%. She will either need a mammogram or a biopsy. The mammogram will be able to provide more information about the suspicious area. A biopsy will give you and the physician definitive results as to what is causing the lump and whether it is dangerous.