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Controversy Continues Over When Women Should Start Annual Mammograms (dateline November 2, 2000)


Most physicians agree that screening mammograms help detect breast cancer in its earliest stages, often several years before a lump can be felt. However, the debate over when women should begin receiving annual screening mammograms has been ongoing. Most physicians and cancer organizations believe that all women 50 years of age and older should have annual mammograms to help detect breast cancer. Yet, many organizations, including the American Cancer Society (ACS), the American College of Radiology (ACR), the American College of Surgeons, and the American Medical Association (AMA), recommend that women should begin receiving annual mammograms at age 40.

According to Robert A. Smith, PhD, Director of Cancer Screening for the American Cancer Society (ACS), breast tumors in women under age 50 tend to progress faster than tumors found in older women. Tumors also tend to be more aggressive in younger women, and the number of breast cancer cases rises significantly among women in their forties. Therefore, the ACS recommends that women begin annual screening mammography at age 40 since the ability to detect a cancer as little as one year earlier is an important advantage in earlier treatment and survival.

However, other groups recommend slightly different guidelines. For example, the National Cancer Institute (NCI) recommends that women in their forties receive mammograms every one to two years and begin annual mammograms at age 50. By contrast, the U.S. Preventive Services Task Force (USPSTF) does not recommend mammograms before age 50.

According to Dr. Smith of the ACS, "organizations may differ in the manner in which they assess evidence and form guidelines. The current USPSTF guidelines were last updated in 1996, which means that data considered for the guidelines was probably only current up to 1995. The NCI guidelines were based on clinical trial data only; some trials included women beginning [screening mammography] at age 40, some at 45, some screened annually, some screened every one to two years… Since the sum total of the trial data analyzed in a meta-analysis shows a benefit, the NCI has chosen to say every one to two years."

Currently, mammography is the only screening exam approved by the U.S. Food and Drug Administration (FDA) to help detect breast cancer in women who do not show any signs or symptoms of breast cancer (such as a lump, skin thickening or dimpling, etc.). Mammography can find approximately 85% of breast cancers.

"Women participate in breast cancer screening with mammography on the basis of the advantage of finding breast cancer when it is small, and before it is symptomatic," said Dr. Smith. "In [women in their forties], screening every two years, or even every 18 months, significantly reduces those chances."

Some women are not comfortable beginning annual mammograms in their forties because of their concerns with radiation from mammography. However, physicians say that the low dose of radiation from mammography equipment used today does not pose a risk to women. Modern mammography systems use extremely low levels of radiation: usually about 0.1 to 0.2 rad dose per x-ray (rad is the scientific unit of measure of radiation energy dose).

To put the mammography dose into perspective, a woman who receives radiation therapy as a treatment for breast cancer will receive several thousand rads over a very short period of time (weeks or months). If a woman had annual screening mammography for 50 years (two x-ray views per breast), beginning at age 40 years and continuing until age 90, she will have only received a total of 10 rads to 20 rads per breast over the course of 50 years.

The Mammography Quality Standards Act (MQSA) was created by the American College of Radiology (ACR) and passed by Congress to mandate rigorous guidelines for x-ray safety during mammography. The MQSA guidelines assure that mammography systems are safe and use the lowest dose of radiation possible. Patients should make sure they are being imaged at an ACR accredited facility using modern mammography systems.

According to Dr. Smith, "breast cancer is a significant health problem for women and incidence begins to rise rapidly in their forties, and annual mammograms are recommended by the ACS, the American Medical Association, and the American College of Radiology because that interval offers the best opportunity to detect breast cancer very early, when treatment is likely to be most successful."

American Cancer Society (ACS) guidelines for the early detection of breast cancer:

  • All women between 20 and 39 years of age should practice monthly breast self-exams and have a physician performed clinical breast exam at least every three years.
  • All women 40 years of age and older should have annual screening mammograms, practice monthly breast self-exams, and have yearly clinical breast exams.

In addition, women with a family history of breast cancer or those who test positive for the BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) mutations may want to talk to their physicians about beginning annual screening mammograms earlier than age 40, as early as age 25 in some cases.

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