Breast cancer is the most common cancer among women in Singapore. 1 in 17 women develops breast cancer in her lifetime. The risk of developing breast cancer increases with age. Breast cancer affects all women, it is the most prevalent in women age 50 years to 59 years in Singapore1.
Common types of breast cancer
The most common types of breast cancer begin either in the milk ducts (ductal carcinoma) or in the milk-producing glands (lobular carcinoma).
In situ breast cancer
In situ (noninvasive) breast cancer refers to cancer which has not spread to breast tissue around the duct or lobule.
Invasive breast cancer
- Invasive ductal carcinoma (IDC) accounts for about 70 percent of all breast cancers.
- Invasive lobular carcinoma (ILC) starts in the milk-producing lobules and then spreads into the surrounding breast tissue.
Symptoms
The commonest presentations of a breast cancer include:
- Breast lump
- Bloody or unusual nipple discharge
- Skin changes
- Persistent rash around the nipple
- Retracted nipple
- Breast pain
Causes
As with most cancers, the exact cause for breast cancer is unknown.
Experts believe that it is multi-factorial involving a combination of genetic and environmental factors.
- Inherited causes include some defects in the genes called breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2) which are transmitted in families.
- Some acquired causes include mutations in genes caused by exposure to radiation.
Risk factors
- Age. The risk of developing breast cancer increases with age.
- Personal history of breast cancer. The risk increases if the woman had breast cancer previously in one breast.
- Family history of breast cancer in first degree relatives such as mother, sister or daughter.
- Genetic predisposition. About 5-10% of breast cancers are inherited. Defects in genes such as BRCA1 or BRCA2 increase the risk of developing breast, ovarian and colon cancers.
- Radiation exposure to chest in childhood or adolescence.
- Early onset of menses and late menopause.
- Hormone replacement therapy with a combination of estrogen and progesterone for four or more years.
- Birth control pills. Use of pills for four years or more is associated with an increased risk of breast cancer.
- Alcohol intake. Excessive consumption of alcohol (> one alcoholic beverage per day) increases the risk of developing breast cancer by 20%.
Diagnosis
See your doctor as soon as possible if you have:
- Discovered a lump which persists.
- Noticed a change in the appearance of the breast or discharge from the nipple.
- Persistent bone aches lasting more than 3 weeks.
Common screening tests include:
- Breast self examination.
- Clinical breast examination to examine the breasts for lumps and to check the armpits for enlarged lymph nodes.
- Screening mammograms which are done on a yearly basis to detect any lump or changes in the breasts.
- Breast Ultrasound to determine if the lump is cystic or solid in structure.
Diagnostic procedures include:
- Ultrasound is done to differentiate between a cyst and solid mass.
- Fine needle aspiration biopsy involves using a thin, hollow needle to withdraw tissue from the lump for microscopic examination.
- Core needle biopsy also involves taking tissue samples using a hollow needle from the lump for microscopic examination.
- Surgical biopsy is the most reliable methods to confirm if the lump is cancerous.
Treatment
The three primary treatment options are: surgery, chemotherapy and radiation which may be used alone or in combination.
Surgery
Breast cancer operations include the following:
- Lumpectomy involves removing only the lump of tumour plus a surrounding area of normal tissue.
- Partial or segmental mastectomy involves removing the tumour as well as some of the breast tissue.
- Simple mastectomy involves removal all the breast tissue.
- Modified radical mastectomy involves removal of the entire breast, including the overlying skin and some underarm lymph nodes (axillary lymph nodes).
Radiation therapy
Radiation therapy uses high-energy X-rays to kill cancer cells and shrink tumors.
Chemotherapy
Chemotherapy uses drugs to destroy cancer cells.
Hormone therapy
Hormone therapy is often used to treat women whose cancers are sensitive to hormones. These include:
- Selective estrogen receptor modulators (SERMs) such as tamoxifen.
- Aromatase inhibitors include anastrozole, letrozole and exemestane.
Prevention
Chemoprevention
Chemoprevention is the use of medications to decrease breast cancer risk.
Two drugs used for breast cancer prevention in high-risk women include:
- Tamoxifen
- Raloxifene
Preventive surgery
Although a radical strategy, preventive surgery has been shown to reduce breast cancer risk in high-risk women.
Options include:
- Prophylactic mastectomy in women who have cancer in one breast, a family history of breast cancer or carry BRCA1 or BRCA2 mutation.
- Prophylactic oophorectomy. Although the procedure is usually performed to reduce ovarian cancer risk, oophorectomy has been shown to reduce the risk of breast cancer.
Lifestyle modifications
- Limiting alcohol intake to less than one drink a day or avoiding alcohol completely.
- Maintain a healthy weight as there is a clear link between obesity and breast cancer.
- Avoid long-term hormone therapy.
- Staying physically active.
- Eating foods high in fiber such as fresh fruits, vegetables and whole grains.
- Consuming more olive oil as oleic acid, the main component of olive oil, appears to suppress the action of some cancer related genes in breast cancer.
1Trends in cancer incidence in Singapore 1998-2002, Singapore Cancer Registry 2002
Source: Health Promotion Board, Singapore
www.spb.gov,sg
