Although scientists have been able to identify risk factors that increase a woman's chance of developing breast cancer, the exact causes are not known. Excluding cancers of the skin, breast cancer is the most common type of cancer in American women.
Certain factors increase the risk of developing breast cancer. However, having many risk factors does not mean a woman will develop breast cancer, and having no risk factors does not mean she will not develop the disease.
Age is the single-most important risk factor for breast cancer. The chances of developing the disease increase with age. About 70 percent of women diagnosed with breast cancer each year are over age 50, and almost half are age 65 and older.
Personal risk is also greater if an immediate family member (mother, sister or daughter) has had breast cancer, particularly if it was at an early age. Also, women who have had a breast biopsy that shows certain types of benign disease, such as atypical hyperplasia, are more likely to get breast cancer.
Other risk factors include:
- Having cancer in one breast (may develop in other)
- Late menopause (after age 50)
- Starting menstruation early in life (before age 12)
- Having a first child after age 30
- Never having children
How Can I Protect Myself?
Detection of breast cancer in its early stages - hopefully before it moves outside the breast - can significantly improve the chances that treatment will be successful. The survival rate from breast cancer increases when the disease is detected and treated early.
When a cancer is found in its earliest stages (within the breast), the 5-year survival rate is >97 percent. This means that of 100 women diagnosed with breast cancer at this stage, 97 will be alive after five years. More than half of all breast cancers are diagnosed at this stage. Much of this early detection is done via self-exams and self-screening for breast lumps.
When the cancer has spread outside the breast to nearby tissues (usually the lymph nodes), the 5-year survival rate drops to 77 percent. When the cancer has spread to more distant parts of the body, the >5-year survival rate is 22 percent.
Strategies for Early Detection
There are two methods of early detection that involve physical examination of the breast: breast self examination and clinical breast examination. The American Cancer Society recommends that women age 20 and older do a breast self exam each month. By doing the exam regularly, a woman becomes familiar with the normal feel of her breasts and can more easily notice breast lumps. Any change or breast lump should be reported promptly to a physician.
A clinical breast examination is performed by a physician. Women ages 20 to 39 should have one done every 3 years, and then every year once they turn 40.
Mammography is an important method of early detection that uses low doses of X-rays to take a picture of breast tissue. The purpose of a mammogram is to find abnormalities and breast lumps that are too small to be seen or felt. However, mammograms will not detect all breast cancers, which is why physical breast exams are very important.
To find out if you are at increased risk for breast cancer, consult your physician. The National Cancer Institute (NCI) has made available computer models for predicting risk. Your doctor can tell you your estimated 5-year and lifetime risks for breast cancer.
Breast Cancer and Genetics
Only 5 to 10 percent of breast cancer cases are thought to be hereditary. The two most common genes associated with breast cancer - BRCA1 and BRCA2 - can be inherited from either parent. Therefore, the father's family history of breast cancer is important as well.
At-risk families can take blood tests to screen for mutations in these genes. However, genetic testing is done only when definitely indicated by a strong family history.
What Are my Options if I am at High Risk or Have the "Cancer Genes?"
Through genetics generally only play a small role in breast cancer, high-risk candidates and carriers of the genes associated with breast cancer can exercise several options, including beginning screenings at an earlier age and conducting more frequent mammograms and clinical exams. Some women choose preventive mastectomy to decrease the chances of developing breast cancer, although this doesn't offer complete protection.
Another approach includes chemo-prevention strategies using the anti-estrogen drug tamoxifen (Nolvadex).
In September of 1998, the NCI and the National Surgical Adjuvant Breast and Bowel Project (NSABP) published the report of their breast cancer prevention trial. The trial was designed to determine whether tamoxifen would reduce the incidence of breast cancer in healthy women known to be at high risk. A total of 13,388 women at increased risk of getting breast cancer were given tamoxifen therapy or a placebo daily.
The results of the trial showed a 50 percent reduction in both invasive and non-invasive breast cancer in the treated women. However, tamoxifen may not be suitable for all women at high risk for developing the disease. An informed discussion between a woman and her physician is essential in determining the appropriateness of this treatment option. Those women who should definitely not use tamoxifen include pregnant women or women planning to become pregnant, women with a history of blood clots or stroke or who are taking anticoagulants.
There are an estimated 29 million women at increased risk for breast cancer in this country, and tamoxifen may offer another alternative to watchful waiting or prophylactic mastectomy.
Raloxifene is a new drug that has been approved for the prevention of osteoporosis in postmenopausal women. Early clinical studies of this drug did not find it to be effective in the treatment of breast cancer. However, some recent data suggest that it may have an effect in reducing breast cancer in healthy women. Further studies are being conducted by the NSABP to investigate this theory.
In Cleveland? Detected a Breast Lump?
Cleveland Clinic's Breast Center offers a full range of services from detection to treatment of breast cancer. Contact a specialist today if you have questions or concerns.