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Reviewed by the Faculty of Harvard Medical School

Screening For Breast Cancer

Breast cancer is:

  • the most commonly diagnosed cancer in women
  • the second-leading cause of cancer death in women
  • the leading cause of death from any cause in women aged 45-55

In 2005, an estimated 211,240 new cases will be diagnosed in American women, and approximately 40,410 women will die of the disease.

An individual woman's odds of developing breast cancer depends on her age, as well as other specific risk factors, such as ethnicity, genetics and hormonal factors, including the age of menstruation and menopause. Statistics show that an American woman living to the age of 85 has a one in eight chance of developing breast cancer sometime in her life. The risk is not evenly spread over a women's lifetime. For example, a 25-year-old woman has a lifetime risk of one in eight, but her current risk is only one in 19,608.

How A Woman's Chance Of Developing Breast Cancer Changes With Age
By age 40 1 in 217
By age 50 1 in 53
By age 60 1 in 22
By age 70 1 in 13
By age 80 1 in 9

More than three in four cases of breast cancer occur in women older than 50.

Who Is At Risk?

Any woman can develop breast cancer.

Your risk of breast cancer increases as you age. While some younger women develop breast cancer, most cases are diagnosed in women after menopause.

A number of factors can increase your risk of developing breast cancer, including your family history and the age at which you started having menstrual periods or became pregnant.

What Screening Tests Are Available?

Breast Examination (performed by your doctor)

Regular breast exams by your doctor or other health care provider can play an important role in detecting the first signs of breast cancer. About 10 percent of cancers that are missed by mammography may be detected by a careful examination. All women should have a yearly breast exam beginning at age 40, or earlier if they are at increased risk for breast cancer.

A breast exam will usually be included as part of a general physical or gynecological examination. As part of the examination, your health care provider will usually:

  • Look at the breast for any lumps or skin changes.
  • Examine the nipples for discharge.
  • Feel the breast with one or two hands to check for lumps or other abnormalities.
  • Feel under the arms for swollen lymph nodes.

If anything abnormal is detected, your doctor may order additional tests such as a mammogram, ultrasound, or fine-needle aspiration. In younger women, a repeat examination after one or two menstrual cycles may be all that is needed. Keep in mind that most lumps detected by your health care provider are benign (non-cancerous).

Breast Self-Exams (performed by you)

For many years, doctors have recommended that all examine their own breasts each month to help detect the earliest signs of cancer.

However, recent studies have shown that regular breast self exams do not lower a woman’s risk of dying from breast cancer. In 2003, the American Cancer Society changed its guidelines to say that "it is acceptable for women to choose not to do BSE or to do it occasionally."

Talk with your doctor about whether breast self exams make sense for you.


This simple type of x-ray is the single most important test for the early detection of breast cancer. Studies show that regular mammograms reduce your risk of dying from breast cancer by 30% to 40%.

Most experts agree that women should begin having regular mammograms at age 40. A mammogram should be performed every one to two years, in conjunction with a breast exam.

If anything abnormal is detected on your mammogram, your doctor may order additional tests such as a repeat mammogram, an ultrasound, fine-needle aspiration. Keep in mind that many women who have an abnormal mammogram will turn out to have a benign (non-cancerous) condition.

New Tests To Detect Breast Cancer

A mammogram and a careful examination by your healthcare provider remain the standard method for detecting the earliest signs of breast cancer. However, several promising tests are being developed that may offer certain advantages. Newer screening tests may be particularly useful for women who are at increased risk for breast cancer.

Ultrasound (sonography) uses sound waves to look at breast tissue. Ultrasound is particularly useful at telling whether a lump is a solid mass (worrisome) or whether it is a fluid-filled cyst (usually reassuring). This makes it a good test for examining younger women, who tend to have lumpier, cyst-filled breasts. Ultrasound has been used for many years to diagnose women with breast problems, but some experts feel it may also be useful as a screening test. Since ultrasound will not detect all breast cancers, it is often performed in conjunction with a mammogram.

Magnetic resonance imaging (MRI) uses magnetic waves to construct 3-dimensional pictures of the body. Several studies have shown that breast MRI may be better than mammograms at detecting the earliest signs of cancer in younger, high-risk women. MRI may also be used to more closely examine breast tissue that appears abnormal on a mammogram. While many experts are excited about this type of scan, MRI may be overall less accurate than mammograms, and more likely to give "false positive" results — abnormal results despite the fact the no cancer is present — that can increase a woman’s anxiety. At present, breast MRI should probably not be used a screening test in women at average risk for breast cancer.

Ductal lavage is a new technique for looking for the earliest changes of breast cancer in cells taken from a woman’s breast. A tiny tube is inserted into the hole (duct) where milk flows from the nipple. Fluid is washed through the milk duct, and then spread on a microscope slide. A specially trained technician then examines the fluid for normal and abnormal appearing cells, much in the same way that a Pap smear is examined. If abnormal cells are seen, further testing or treatment may be considered. However, most abnormal cells seen on ductal lavage do not represent breast cancer, and ductal lavage is rarely used to diagnose cancer by itself.

Ductal lavage is a promising technology, but further studies are needed before this test is appropriate for widespread use. Like the other tests mentioned above, ductal lavage is probably most useful in women at increased risk for breast cancer.

Genetic testing may help to identify women who have inherited a gene that puts them at high risk for breast cancer. It is important to remember that while many women have a family member who has been diagnosed with breast cancer, only about 10% of breast cancer cases appear to be linked to an inherited genetic problem. At present, genetic testing for breast cancer is mostly focused on the BRCA1 and BRCA2 cancer genes. These genes are most commonly found in Jewish women with Eastern European (Ashkenazi) backgrounds, but other women can carry the BRCA genes as well.

Genetic testing can be a very useful technique, but it is not for everyone. Women who are found to have one of the BRCA genes may have to make difficult decisions about methods to prevent breast cancer, for example whether they should have breast-removing treatment or take preventive chemotherapy. It is also important to remember that women who test negative for a breast cancer gene still remain at risk for developing a non-inherited form of the disease.

Aetna Member: If you would like more information about breast cancer and breast cancer prevention, please call (888) 322-8742.
Miembros de Aetna: Si desean mayor información sobre el cáncer de seno y sobre su prevención por favor llame al (888) 322-8742.

Last updated February 16, 2005