Getting to know your enemy

No two breast cancers are the same. Most are carcinomas. Some carcinomas develop in the breast lobules, the glands that produce milk, (lobular carcinomas) others develop in tissues known as terminal ductolobular units (ductal carcinomas). Other, less common, breast cancers include Paget’s disease, a cancer of the areola and nipple, and inflammatory carcinoma. The least common breast cancers are sarcomas, arising in the muscle, fat, or connective tissues of the breast and primary lymphomas found in the lymphatic tissues.

Over the last 30 years, although the incidence of breast cancer has increased, the mortality from breast cancer has decreased by over 20%. When you were diagnosed with breast cancer a small amount of tissue from the cancer will have been sent away for testing – to find out more about it. Things can get really technical when those results come back! Your doctor will prescribe treatment for your particular cancer based, in part, on whether it is hormone receptor positive, HER2 positive or BrCa related.

What is HER2 Positive?

HER2 (Human Epidermal growth factor Receptor 2) is a protein that occurs on the surface of some breast cancer cells. When cancer cells over express the HER2 protein they are said to be HER2 positive.

15 – 20 percent of breast cancers are HER2 positive. HER2 positive breast cancers can benefit from trastuzumab therapy, which directly targets the HER2 receptor. Trials show that chemotherapy followed by targeted therapy with trastuzumab can decrease the risk of relapse for women with HER2 positive tumours.

What is BrCa1 and 2?

BrCa1 and BrCa2 (Breast Cancer susceptibility genes 1 and 2) are human tumour suppressing genes. Normally BrCa1 and BrCa2 help to prevent uncontrolled cell growth. Certain people carry mutated versions of these genes that have been linked to hereditary breast and ovarian cancers. The chances that a woman who has the mutated BrCa gene will develop breast cancer is about five times greater than in women without the gene. Genetic causes of breast cancer account for 10% of all cases.

If you are diagnosed as having mutated BrCa1 or 2 genes it is important that you tell ALL of your blood relatives (even the men) so that they can go for testing.

What is Hormone Receptor-Positive?

In certain breast cancers the cancer cell growth increases in the presence of oestrogen and/or progesterone, female hormones that are produced in the body. Hormone receptor-positive breast cancers are treated with hormone therapies, hormone receptor-negative breast cancers are not.

Oestrogen receptor-positive breast cancers tend to be progesterone receptor-positive and oestrogen receptor-negative breast cancers are often progesterone receptor-negative but, sometimes, a breast cancer can be positive for oestrogen receptors but negative for progesterone receptors.

Written by Dr Carol-Ann Benn

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