Breast cancer, also known as carcinoma of the breast, starts when a single cell in the tissue of that breast starts to divide and grow in an abnormal way.  There are different types of breast cancer and it is important that an accurate diagnosis is made so that the most appropriate treatment can be planned.

Symptoms of breast cancer

Most common types of breast cancer

Lobular Carcinoma in Situ (LCIS)

This is a pre-invasive carcinoma, where there are abnormal changes to the cells lining the lobules within the breast. The presence of LCIS may indicate that there is a small increased risk of developing breast cancer but often no treatment is required other than careful monitoring of the condition.

Ductal Carcinoma in Situ (DCIS)

This is an early form of breast cancer where the malignant cells are only found within the milk ducts and have not developed the ability to spread into either the breast tissue or other parts of the body.  As it does not spread, it is sometimes described as pre-cancerous, intraductal or non-invasive carcinoma. It does not usually present any visible or palpable symptoms and is most commonly diagnosed during routine mammography.

Invasive Ductal Carcinoma

Most breast cancers fall within this category. The cancer cells are no longer contained within the ducts but have spread to the surrounding breast tissue. They also have the ability to spread to other parts of the body. The most common sign of an Invasive Ductal Carcinoma is an abnormal lump, or sometimes an area of nodularity (glandular breast tissue) without a definite lump. There may also be nipple changes or a nipple discharge – however these symptoms are not usually due to cancer if there is no lump. Sometimes a swelling occurs under the arm.

Invasive Lobular Carcinoma

This cancer occurs when malignant cells in the lobules at the end of the breast ducts have begun to spread out into the breast tissue. It is usually no more serious than other types of cancer but it does behave differently in that, when it occurs, the entire breast tends to be genetically, or gnomically unstable. It can also occur in both breasts at the same time and has a slightly higher risk, at a later date, of occurring in the opposite breast. These carcinomas tend to be less receptive to hormone treatment. Lobular cancers may not show up on a mammogram as they have the same density as normal breast tissue. Fortunately they are often palpable so it is important that everyone has a clinical examination. 

Stages of breast cancer

Two of the most commonly used staging systems are a numbered staging system and the TNM (Tumour, Node and Metastases) staging system.

Grades of breast cancer

Grading is about how the cancer cells look under the microscope when compared with normal cells.