Breast Cancer

Overview

A woman's breast is made up of milk glands and milk ducts, surrounded by fatty tissue and connective supports. Uncontrolled growth of cells in any of these breast tissues can cause breast cancer.

Breast cancer is the most common cancer among women. It tends to occur at an earlier age than do other cancers or heart attacks and strokes. Chances of developing breast cancer rise dramatically as women age: at age 25, the chances of getting the disease are less than 1 in 1,000; at age 50, the incidence has gone up to 1 in 63 women, and at age 75, it's 1 in 15. Breast cancer is rare in men, accounting for about 3% of all cases.

Causes

The body's cells reproduce themselves throughout your lifetime, as tissues wear out and their cells are replaced in a controlled manner. Breast cancer - like all cancers - occurs when that control is lost, and cells begin to divide at an unusually high rate.

No single trigger or cause has been identified for breast cancer. Certain risk factors exist, though, that increase a woman's chance of developing it:

• age: it's more common in women over 50
• family history: if a woman's mother or sister had the disease before menopause, this is occasionally associated with one of two genes linked to breast cancer
• previous breast cancer
• family history of cervical, uterine, colorectal, or ovarian cancers
• age of pregnancy: women who haven't had children, or whose first child was born after age 30, run a slightly higher chance of breast cancer than women who had children before age 25
• age of menstruation: starting periods at a young age - under 12 years old - or entering menopause later - over age 55 - increases breast cancer risks
• recent research suggests that women who start smoking regularly within five years of the onset of their menstrual periods are 70% more likely to develop breast cancer before the age of 50 than non-smokers.
• alcohol consumption contributes to the risk of breast cancer, with women who consume three drinks a day having a 40% increased risk of this disease
• hormone replacement therapy (HRT - estrogen plus progesterone): increases the risk of breast cancer slightly after five years of therapy
• oral contraceptives: increase risks slightly, if used over many years
• obesity with excess caloric and fat intake

The increased risks of getting breast cancer associated with the above factors are often statistically quite small. Any concerns should be discussed with your doctor.

Symptoms

Nine out of ten women are the first to notice a lump or mass in their breast. It usually isn't painful, but can cause an unusual sensation in the area where the lump is. When a tumour grows in the milk ducts, bleeding can occur from the nipple. The size or shape of the breast may change. As well, the nipple might draw in, or some of the skin will pull in causing what looks like a dimple to appear. While these might be early signs of breast cancer, they might also indicate another non-cancerous disease. In fact, about 8 out of 10 breast growths are non-cancerous. However, a doctor should be consulted to determine the exact cause of the lump.

The most serious complication of breast cancer is metastasis. That's when some cells from a tumour break off and move to other areas of the body - through either the blood or the lymphatic vessels - invading the tissue at new, possibly distant sites. When breast cancer cells metastasize, it's most commonly to the lymph nodes, lungs, liver, bones, brain, and skin. It can take years - even after the breast tumour is diagnosed and treated - before cancer that has spread from the original tumour appears. Once metastatic tumours are discovered, chances are that the cancer has spread to other locations as well, even if they remain undetected.

Treatment

Early detection of breast cancer minimizes the likelihood that the cancer has spread, and increases the chances of making a complete recovery. Treatment depends on individual circumstances, such as the rate of growth, how it responds to treatment, and whether or not it has spread.

When the tumour is confined to the breast, the best choice is surgery, followed by systemic therapy and possibly also radiation. Part or all of the breast is surgically removed soon after the diagnosis to avoid having the cancer spread. Removal of a small part of the breast - only the tumour and some surrounding tissue - is called a lumpectomy, or partial mastectomy if a larger area of the breast is removed. A simple mastectomy involves removing the whole breast, and a radical mastectomy includes the underlying chest muscle and tissue as well. The lymph nodes in the underarms may also be taken out.

Systemic therapy consists of chemotherapy and hormonal therapy. Chemotherapy is often given over six to eight months, and hormonal therapy may continue for five years or longer, if tests on the original cancer find receptors for hormones (receptor-positive cancers). The use of systemic therapy is now very common, and greatly reduces the risk of recurrence of the cancer, often by as much as 50%.

On rare occasions, systemic therapy is used prior to surgery. This is called neoadjuvant therapy. This type of treatment is used to improve chances of recovery, to allow surgery to take place successfully, and to assess the response of the tumour to systemic therapy (which cannot occur if the tumour is already removed).

Radiation therapy is often administered after lumpectomy or partial mastectomy. It is used if the resection margins are very close, or if the tumour was large and involved a lot of lymph nodes. Radiation kills any remaining cancer cells in the breast and sometimes in the armpit and chest wall as well. Side effects of radiation therapy are the result of healthy tissue in the area being destroyed, and go away on their own following the completion of therapy.

While successful surgery and radiation therapy rely on exact knowledge of where the tumour is located, systemic therapy does not. Chemotherapy involves taking one or more medications to destroy secondary tumours or in an attempt to suppress growth of cancer cells that may appear in other locations. Hormone therapy works on cancerous cells that have estrogen receptors, making them susceptible to estrogen-blocking medications. The source of the hormones that stimulate growth - ovaries or the adrenal gland - may also be surgically removed or destroyed using X-rays.

As far as we know, breast cancer can't be prevented. Research is ongoing to confirm that medications known as anti-estrogens can help prevent breast cancer for women at high risk. In the meantime, keep in mind the non-drug steps you can take to reduce your risk of breast cancer:

• exercise regularly
• eat a healthy, low-fat diet with lots of fruits and vegetables
• reduce alcohol intake (one to two drinks per day slightly increases your risk)

In addition, women should perform monthly breast self-examinations - your doctor can show you the correct way to do this. From age 50, women of average risk should also have mammograms and physical examinations every two years. These measures help detect any unusual lumps or abnormalities in breast tissue. Early detection can make a big difference in successful treatment.

Other tips:

A suspicious lump in your breast should be checked by your doctor. Aside from an extensive physical examination, the doctor will also want to do a mammogram - a low-level X-ray that can show abnormal areas in your breast. An ultrasound can sometimes be performed to see if the lump is a fluid-filled cyst or a solid growth. Even if the lump which can be felt is not visible on the mammogram, some sort of biopsy may need to be done.

Using a needle, fluid can be removed from a cyst to check if it contains cancerous cells. A solid lump must be analyzed under a microscope. This requires either a needle biopsy or a surgical biopsy to be performed, to remove some or all of the lump.

Cancerous cells can be tested for the presence of estrogen- or progesterone-receptors. Other tests - including a chest X-ray, bone scan, and liver function evaluation - are conducted to help the doctor determine whether the cancer has spread.

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