Cancer cells are different from normal cells, as they go on to grow and multiply when they should not; to form lumps and/or tumours.
Different Types of Breast Cancer
There are different types of breast cancer, which are classed as invasive and non-invasive depending on their ability to spread to neighboring tissues.
Non Invasive Breast Cancers
The most common type of non-invasive breast cancer is Ductal Carcinoma In Situ (DCIS). Cancer cells are found inside the milk ducts but have not yet spread through the walls of the ducts into the breast tissue. The importance of DCIS is that it may over time develop into the invasive form of breast cancer; this process is however very unpredictable and may take many years. Since there is often no lump, non-invasive breast cancer is commonly detected by breast screening. Nearly everyone diagnosed with DCIS is able to have the cancer in the affected breast completely removed.
Another form of non-invasive breast cancer is Lobular Carcinoma In Situ (LCIS). It is most often found by chance in a sample of breast tissue removed for some other reason. LCIS is a diffuse process, the main relevance of which is that it identifies a woman who is at increase risk or the development of breast cancer in the future. LCIS is managed by regular mammogram check-ups to look out for the earliest signs of a problem.
Invasive Breast Cancers
Invasive breast cancer usually comes to notice because it produces a lump in the breast. The most common type of invasive breast cancer is called Invasive Ductal Carcinoma (IDC) which is responsible for around 80% of all breast cancers. These cancer cells are found in the ducts and in the breast tissue. These cells also have the ability to spread to other parts of the body.
Invasive Lobular Carcinoma (ILC) accounts for between 10-15% of all breast cancers. With ILC, cancer cells initially grow in the lobes of the breast and have the ability to spread to other areas of the breast and to other parts of the body.
Secondary Breast Cancer
The malignant tumours (cancers) have the ability to invade surrounding areas. Sometimes cells from the malignant tumours break away and spread to other areas of the body (through the blood stream and lymphatic system) where they may grow to form "secondary" tumours. Another name for a secondary tumour is a metastasis. The breasts have a rich blood supply and an extensive lymph glad drainage system, which can be important factors in the spread of the disease.