Breast Cancer

Breast cancer is a kind of cancer that develops from breast cells. Breast cancer usually starts off in the inner lining of milk ducts or the lobules that supply them with milk. A malignant tumor can spread to other parts of the body. A breast cancer that started off in the lobules is known as lobular carcinoma, while one that developed from the ducts is called ductal carcinoma.

The vast majority of breast cancer cases occur in females. This article focuses on breast cancer in women. To read about breast cancer in men (male breast cancer).

Breast cancer is the most common invasive cancer in females worldwide. It accounts for 16% of all female cancers and 22.9% of invasive cancers in women. 18.2% of all cancer deaths worldwide, including both males and females, are from breast cancer.

Breast cancer rates are much higher in developed nations compared to developing ones. There are several reasons for this, with possibly life-expectancy being one of the key factors - breast cancer is more common in elderly women; women in the richest countries live much longer than those in the poorest nations. The different lifestyles and eating habits of females in rich and poor countries are also contributory factors, experts believe.

What is the difference between invasive and non-invasive breast cancer?

Invasive breast cancer - the cancer cells break out from inside the lobules or ducts and invade nearby tissue. With this type of cancer, the abnormal cells can reach the lymph nodes, and eventually make their way to other organs (metastasis), such as the bones, liver or lungs. The abnormal (cancer) cells can travel through the bloodstream or the lymphatic system to other parts of the body; either early on in the disease, or later.

Non-invasive breast cancer - this is when the cancer is still inside its place of origin and has not broken out. Lobular carcinoma in situ is when the cancer is still inside the lobules, while ductal carcinoma in situ is when they are still inside the milk ducts. "In situ" means "in its original place". Sometimes, this type of breast cancer is called "pre-cancerous"; this means that although the abnormal cells have not spread outside their place of origin, they can eventually develop into invasive breast cancer.

What are the signs and symptoms of breast cancer?

A symptom is only felt by the patient, and is described to the doctor or nurse, such as aheadache or pain. A sign is something the patient and others can detect, for example, a rash or swelling.

The first symptoms of breast cancer are usually an area of thickened tissue in the woman's breast, or a lump. The majority of lumps are not cancerous; however, women should get them checked by a health care professional.

According to the National Health Service, UK, women who detect any of the following signs or symptoms should tell their doctor:

• A lump in a breast
• A pain in the armpits or breast that does not seem to be related to the woman's menstrual period
• Pitting or redness of the skin of the breast; like the skin of an orange
• A rash around (or on) one of the nipples
• A swelling (lump) in one of the armpits
• An area of thickened tissue in a breast
• One of the nipples has a discharge; sometimes it may contain blood
• The nipple changes in appearance; it may become sunken or inverted
• The size or the shape of the breast changes
• The nipple-skin or breast-skin may have started to peel, scale or flake

Although the precise causes of breast cancer are unclear, we know the main risk factors. Still, most women considered at high risk for breast cancer do not get it, while many with no known risk factors do develop breast cancer. Among the most significant factors are advancing age and a family history of breast cancer. Risk increases for a woman who has certain types of benign breast lumps and increases significantly for a woman who has previously had cancer of the breast or the ovaries.

A woman whose mother, sister, or daughter has had breast cancer is two to three times more likely to develop the disease, particularly if more than one first-degree relative has been affected.  Researchers have now identified two genes responsible for some instances of familial breast cancer. These genes are known as BRCA1 and BRCA2. About one woman in 200 carries the genes. Having one of them predisposes a woman to breast cancer but does not ensure that she will get it.

Generally, women over 50 are more likely to get breast cancer than younger women, and African-American women are more likely than Caucasians to get breast cancer before menopause.

A link between breast cancer and hormones is gradually becoming clearer. Researchers think that the greater a woman's exposure to the hormone estrogen, the more susceptible she is to breast cancer. Estrogen tells cells to divide; the more the cells divide, the more likely they are to be abnormal in some way, possibly becoming cancerous.

A woman's exposure to estrogen and progesterone rises and falls during her lifetime, influenced by the age she starts and stops menstruating, the average length of her menstrual cycle, and her age at first childbirth. A woman's risk for breast cancer is increased if she starts menstruating before age 12, has her first child after 30, stops menstruating after 55, or has a menstrual cycle shorter or longer than the average 26-29 days. Current information indicates that the hormones in birth control pills probably do not significantly increase the risk. Some studies suggest that taking hormone replacement therapy after menopause may increase risk, especially when taken for more than five years. The jury is still somewhat out on this matter though. Heavy doses of radiation therapy may also be a factor, but low-dose mammograms pose almost no risk.

The link between diet and breast cancer is debated. Obesity is a noteworthy risk factor, and drinking alcohol regularly -- particularly more than one drink a day -- may promote the disease. Many studies have shown that women whose diets are high in fat are more likely to get the disease. Researchers suspect that if a woman lowers her daily calories from fat -- to less than 20%-30% -- her diet may help protect her from developing breast cancer.