Understanding Breast Cancer

The Breast
Women and men both have breasts.In women, breasts are made up of milk glands. The milk gland consists of lobules, where milk is made, and tubes called ducts that take milk to the nipples.In men, the development of the lobules is suppressed at puberty by testosterone, the male sex hormone.
Both female and male breasts contain supportive fibrous tissue and fatty tissue. Some breast tissue extends into the armpit (axilla). The armpits contain a collection of lymph nodes (also called lymph glands), which are part of the lymphatic system. The lymphatic system is part of the immune system and protects the body against disease and infection.

See the diagram








What is breast cancer?
Breast cancer starts in the ducts or lobules of the breast. Cells lining the ducts or lobules can grow out of control and develop into cancer.
Some breast cancers are found when they are still confined to the ducts or lobules of the breast. This is called pre-invasive breast cancer. The most common types are ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).
Most breast cancers are found when they are invasive. This means the cancer has spread outside the ducts or lobules of the breast into surrounding tissue.

There are several types of invasive breast cancer :
- Early breast cancer: contained in the breast but may have spread to one or more lymph nodesin the armpit.
- Locally advanced breast cancer: may have spread to places near the breast, such as the chest(including the skin, muscles or bones of the chest), but the cancer isn’t found in other areas of the body.
- Metastatic breast cancer: the cancer cells spread from the breast to other areas of the body,such as the bones, liver or the lungs. It may also be called advanced breast cancer.

How common is it?
Breast cancer is a common cancer diagnosed in women.About one in 11 women in NSW will develop breast cancer by the age of 75. Breast cancer can occur at any age. It is more common in women aged over 60 though around one-quarter of women are younger than 50. In NSW each year, around 4000 women are diagnosed with breast cancer.Men can also develop breast cancer, although this is rare. Around 30 men are diagnosed each year in NSW; this accounts for about 1% of all breast cancer.

What are the causes?
The exact cause of breast cancer is not known, but some factors may increase the risk:
- getting older
- more than half the women who are diagnosed with breast cancer are over 55
- having several close relatives, like a mother, sister or daughter, diagnosed with breast cancer
– these relatives can be from either the mother’s or father’s side of the family
- if you have had breast cancer before
- if you have had certain breast conditions such as atypical ductal hyperplasia, ductal carcinomain situ or lobular carcinoma in situ.

Some other factors that may increase a woman’s risk by a small amount include:
- not having children, or having a first child after the age of 30
- early age at first period (before 12 years)
- later age at natural menopause (after 55 years)
- drinking alcohol (more than two drinks a day)
- obesity or putting on a lot of weight after menopause
- using the oral contraceptive pill
– the risk is higher while taking the pill but goes down afteryou stop taking it
- not breastfeeding
- taking hormone replacement therapy (HRT) after menopause, especially if taken for fiveyears or longer.

Having some of these risk factors does not mean that you will develop breast cancer. Most women with breast cancer have no known risk factors, aside from getting older.

Breast cancer usually occurs in men over the age of 60 and is most common in men who have:
- several close members of their family (male or female) who have had breast cancer
- a relative diagnosed with breast cancer under the age of 40
- several members of the family with cancer of the ovary or colon- a rare genetic syndrome called Klinefelter’s syndrome. Men with this syndrome have threesex chromosomes (XXY) instead of the usual two (XY).

Inherited breast cancer gene
An inherited gene change may cause a small number (about 5%) of breast cancers. Two breast cancer genes have been found: BRCA1 and BRCA2.Women in families with an inherited gene change could be at increased risk of ovarian cancer. Men in these families may also be at more risk of breast cancer and prostate cancer.

People with a strong family history of breast cancer may have inherited a gene change, perhaps caused by BRCA1 or BRCA2. If you’re concerned about the health of your mother, sister or daughter, talk to your doctor about genetic testing.