Breast Cancer

Overview

Cancer is not a single disease with a single cause and a single type of treatment. There are more than 200 different types of cancer, each with its own name and treatment. Although cells in different parts of the body may look and work differently, most repair and reproduce themselves in the same way. Normally, cells divide in an orderly and controlled way. But if for some reason the process gets out of control, the cells carry on dividing and develop into a lump called a tumour. Tumours are either benign (non-cancerous) or malignant (cancerous). Doctors can tell if a tumour is benign or malignant by removing a piece of tissue (biopsy) and examining a small sample of cells under a microscope.

In a benign tumour the cells do not spread to other parts of the body and so are not cancerous. However, they may carry on growing at the original site, and may cause a problem by pressing on surrounding organs.

In a malignant tumour the cancer cells have the ability to spread beyond the original area of the body. If the tumour is left untreated, it may spread into surrounding tissue. Sometimes cells break away from the original (primary) cancer. They may spread to other organs in the body through the bloodstream or lymphatic system.

The lymphatic system is part of the immune system – the body’s natural defence against infection and disease. It’s made up of organs such as bone marrow, the thymus, the spleen, and lymph nodes. The lymph nodes throughout the body are connected by a network of tiny lymphatic tubes (ducts). The lymphatic system has two main roles: it helps to protect the body from infection and it drains fluid from the tissues. When the cancer cells reach a new area they may go on dividing and form a new tumour. This is known as a secondary cancer or a metastasis.

Breast cancer is the most common cancer in the UK. About 46,000 women get breast cancer in the UK each year. Most of them (8 out of 10) are over 50, but younger women, and in rare cases men, can also get breast cancer. Estimated new cases and deaths from breast cancer in the United States in 2012 are: New cases: 226,870 (female); 2,190 (male); Deaths: 39,510 (female); 410 (male.)

From 1999 to 2005, breast cancer incidence rates in the U.S. decreased by about 2% per year. The decrease was seen only in women aged 50 and older. One theory is that this decrease was partially due to the reduced use of hormone replacement therapy (HRT) by women after the results of a large study called the Women’s Health Initiative were published in 2002. These results suggested a connection between HRT and increased breast cancer risk.

Anatomy of the breast: A woman’s breasts are made up of fat, connective tissue and thousands of tiny glands, known as lobules, which produce milk. If a woman has a baby, the milk is delivered to the nipple through tiny tubes called ducts, which allow her to breastfeed.
Types of breast cancer: There are several different types of breast cancer, which can develop in different parts of the breast. Breast cancer is often divided into non-invasive and invasive types.

• Non-invasive breast cancer: Non-invasive breast cancer is also known as cancer or carcinoma in situ, or pre-cancerous cells. This cancer is found in the ducts of the breast and has not developed the ability to spread outside the breast. This form of cancer rarely shows as a lump in the breast and is usually found on a mammogram. The most common type of non-invasive cancer is ductal carcinoma in situ (DCIS).
• Invasive breast cancer: Invasive cancer has the ability to spread outside the breast, although this does not mean it necessarily has spread. The most common form of breast cancer is invasive ductal breast cancer, which develops in the cells that line the breast ducts. Invasive ductal breast cancer accounts for about 80% of all cases of breast cancer and is sometimes called ‘no special type.’
• Other types of breast cancer: Other less common types of breast cancer include invasive lobular breast cancer, which develops in the cells that line the milk-producing lobules, inflammatory breast cancer and Paget’s disease of the breast. It is possible for breast cancer to spread to other parts of the body, usually through the lymph nodes (small glands that filter bacteria from the body) or the bloodstream. If this happens, it is known as secondary or metastatic breast cancer.