Types of Breast Cancer

There are several different kinds of breast cancer. However, the majority of breast cancer cases are classified as either in situ or invasive.

Lobular Carcinoma In Situ (LCIS)

Lobular carcinoma in situ describes breast cancer that is confined to the milk-producing glands (lobules) of the breast. Tumors classified as LCIS are made up of small uniform cells that are similar to cells found in breast lobules. LCIS will not progress to invasive breast cancer; therefore it is considered a risk factor for the development of invasive cancer rather than a true precursor. It is also referred to as lobular neoplasia (LN), a more inclusive description that also includes atypical lobular hyperplasia (ALH), another abnormal breast finding.

Lobular carcinoma in situ is most commonly found in premenopausal women between the ages 40 and 50. It is not usually found on a mammogram and generally does not produce a lump. LCIS tumors are usually HER2 negative (-) and ER/PR positive (+) and therefore may be treated with hormonal therapy (tamoxifen). Overall LCIS is highly treatable and in many cases continued observation is enough.

Ductal Carcinoma In Situ (DCIS)

Ductal carcinoma in situ describes breast cancer that is confined to the milk ducts of the breast. Tumors classified as DCIS are made up of irregular cells that resemble cells found in the ductal system of the breast. Unlike LCIS, DCIS can be detected on a mammogram and usually does produce a lump. accounts for 20% of all breast cancer detected with mammography and about 85% of in situ cancers diagnosed each year in the United States. Most cases of DCIS (~98%) will not develop metastasis, but around 50% progress to invasive breast cancer (IBC).

Types of Breast Cancer II

Invasive Lobular Carcinoma (ILC)

Invasive lobular carcinoma develops in the milk-producing glands (lobules) of the breast. ILC has the ability to spread to other parts of the body to other parts of the body (most commonly bone, brain, liver, and lungs) either through the bloodstream or the lymphatic system.

Women over the age of 40 have an increased risk of developing invasive lobular carcinoma, with most cases occurring in women between the ages 45-56.

Invasive Ductal Carcinoma (IDC)

Invasive ductal carcinoma is the most common type of invasive breast cancer, responsible for almost 85% of cases. IDC starts in the milk ducts and invades the surrounding tissue. IDC has the ability to move to other parts of the body (most commonly bone, brain, liver, and lungs) either through the bloodstream or the lymphatic system. IDC develops as a hard lump with irregular borders that usually shows up as a spiked mass on a mammogram.
Women over the age of 40 have an increased risk of developing invasive ductal carcinoma, with around 50% of cases occurring in women over the age of 65.