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Breast cancer is one of the most common forms of cancer in the world. There are more than 55,000 new cases in Britain every year, and the disease claims the lives of 11,500 women. In the US it affects 266,000 people and kills 40,000 every year. But what causes it and how can it be treated?

What is breast cancer?

It comes from a cancer cell that develops in the lining of a duct or lobe in one of the breasts.

When the breast cancer has spread to surrounding tissue, it is called ‘invasive’. Some people are diagnosed with ‘carcinoma in situ’, where no cancer cells have grown outside the duct or lobule.

Most cases develop in people over the age of 50, but sometimes younger women are also affected. Breast cancer can develop in men, although this is rare.

Staging indicates how big the cancer is and whether it has spread. Stage 1 is the earliest stage and stage 4 means the cancer has spread to another part of the body.

The cancer cells are classified from low, which means slow growth, to high, which means fast growth. High-grade cancers are more likely to come back after they are first treated.

What causes breast cancer?

A cancerous tumor starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or changes certain genes in the cell. This causes the cell to become abnormal and multiply ‘out of control’.

Although breast cancer can develop for no apparent reason, there are some risk factors that can increase its likelihood, such as genetics.

What are the symptoms of breast cancer?

The usual first symptom is a painless lump in the breast, although most are not cancerous and are fluid-filled cysts, which are benign.

The first place breast cancer usually spreads to is the lymph nodes in the armpit. When this happens, a swelling or lump develops in the armpit.

How is breast cancer diagnosed?

• Initial assessment: A doctor examines the breasts and armpits. They may do tests such as a mammogram, a special X-ray of the breast tissue that can indicate the possibility of tumors.
• Biopsy: A biopsy involves removing a small piece of tissue from a part of the body. The sample is then examined under a microscope to look for abnormal cells. The sample can confirm or rule out cancer.

If you are confirmed to have breast cancer, further tests may be needed to assess whether the cancer has spread. For example, blood tests, an ultrasound of the liver or an X-ray of the chest.

How is breast cancer treated?

Treatment options that may be considered include surgery, chemotherapy, radiotherapy and hormone treatment. A combination of two or more of these treatments is often used.

• Surgery: Breast-conserving surgery or removal of the affected breast, depending on the size of the tumor.
• Radiotherapy: A treatment that uses high-energy beams of radiation aimed at cancerous tissue. This kills cancer cells or prevents them from multiplying. It is mainly used as an adjunct to surgery.
• Chemotherapy: A cancer treatment that uses anti-cancer drugs that kill cancer cells or prevent them from multiplying.
• Hormone treatments: Some types of breast cancer are affected by the ‘female’ hormone estrogen, which can stimulate cancer cells to divide and multiply. Treatments that lower the levels of these hormones or prevent them from working are often used in people with breast cancer.

How successful is the treatment?

The outlook is best in those who are diagnosed when the cancer is still small and has not spread. Surgical removal of a tumor at an early stage can then give a good chance of cure.

Thanks to routine mammography offered to women between the ages of 50 and 71, more cases of early-stage breast cancer are being diagnosed and treated.

For more information, visit breastcancernow.org or call the free helpline on 0808 800 6000