Breast Cancer Screening: Mammography, in the Spotlight

Kari Bohlke, ScD

Although the idea of cancer screening seems simple and has intuitive appeal—catch the cancer before symptoms develop, treat it, and improve outcomes—the reality is more complex. Some screening programs, such as Pap testing for cervical cancer, have produced dramatic declines in mortality from the disease being screened for, but others have a more modest effect on survival and carry some risks. Though the balance may still tip in favor of screening, it’s important to learn what we can to make a fully informed decision.

In the case of mammographic screening for breast cancer, the most important potential benefit is a reduction in breast cancer mortality. Mammography doesn’t reduce breast cancer mortality to the same extent that the Pap test reduces cervical cancer mortality, but the benefit is substantial enough that the test is strongly recommended for certain groups of women.

Potential risks of mammography include false-positive test results (which lead to unnecessary additional testing), false-negative test results (a missed cancer), and overdiagnosis. Overdiagnosis refers to the diagnosis of a cancer that will never cause health problems during the life of a patient.

A challenging aspect of making screening recommendations is that the likelihood of these benefits and risks varies by factors such as age and risk of breast cancer. Young women, for example, are more likely than older women to experience some of the downsides of mammographic screening and are also less likely to derive a benefit. But even among young women, the balance of risks and benefits depends on a woman’s underlying risk of breast cancer.

Given these complexities, it’s not surprising that different groups of experts have reached different conclusions about when routine screening of average-risk women should begin. These different recommendations do not need to be a source of stress, however; you can consider the full range of options and, in consultation with your healthcare provider, make the decision that’s right for you.

Screening Women at Average Risk of Breast Cancer

So what are current recommendations?  For women at average risk of breast cancer, the American Cancer Society recommends the following:

  • Yearly mammograms starting at age 40 and continuing for as long as a woman is in good health
  • Clinical breast exam about every three years for women in their twenties and thirties and every year for women 40 and older
  • Women should know how their breasts normally look and feel and report any breast change promptly to their healthcare provider. Breast self-exam is an option for women starting in their twenties.

Different recommendations for screening mammography were released by the US Preventive Services Task Force (USPSTF) in November 2009. The USPSTF recommends that routine screening mammography be conducted every two years starting at age 50. For younger women the USPSTF notes, “The decision to start regular, biennial screening mammography before the age of 50 years should be an individual one and take patient context into account, including the patient’s values regarding specific benefits and harms.” Although the USPSTF recommendations captured headlines, the debate about screening women in their forties is not a new one.

What does all of this mean? Starting at age 50, it’s pretty clear-cut: routine mammography is recommended. Younger women have a decision to make. The American Cancer Society continues to recommend routine annual screening of women in their forties. The USPSTF recommends that women in their forties make an individual decision after considering the available evidence. Ultimately, it’s up to us.

Screening Women at High Risk of Breast Cancer

Women who are at high risk of breast cancer are generally advised to begin screening at a younger age than other women (by age 30 or so, although high-risk women should discuss this with their doctor) and to be screened with both mammography and magnetic resonance imaging (MRI).1 The addition of MRI increases the sensitivity of screening; this means that if breast cancer is present, it is more likely to be detected.

The American Cancer Society considers women to be at high risk if they have a 20 percent or greater lifetime risk of breast cancer. Women who fall into this category include those with a known (or likely) BRCA1 or BRCA2 mutation, those with another genetic condition linked with high breast cancer risk, and those who received radiation therapy to the chest as a child or young adult.

MRI may also be considered for some women with a moderately increased risk of breast cancer (15 to 20 percent lifetime risk of breast cancer). Routine MRI screening is not recommended for women at lower risk of breast cancer.

Breast Changes Warrant Attention No Matter What Your Age

The screening guidelines discussed above are intended to detect breast cancer at an early stage in women who don’t have symptoms of breast cancer. If you have breast symptoms (such as a lump or other breast change), you should be evaluated no matter what your age.

The message? Learn as much as you can and take control of your health. Each year roughly 200,000 women are diagnosed with breast cancer in the United States,2 but earlier detection and advances in treatment have both contributed to important improvements in survival.

References

1. Mammograms and Other Breast Imaging Procedures. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003178-pdf.pdf. Accessed June 17, 2011.

2. Cancer Facts & Figures 2010. American Cancer Society website. Available at: http://www.cancer.org/Research/CancerFactsFigures/CancerFactsFigures/cancer-facts-and-figures-2010. Accessed June 17, 2011.

3. Pisano ED, Gatsonis C, Hendrick E, et al. Diagnostic performance of digital versus film mammography for breast-cancer screening. New England Journal of Medicine. 2005;353:1773-83.

4. FDA approves first 3-D mammography imaging system [news release]. US Food and Drug Administration website. Available at: http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm243072.htm. February 11, 2011.

5. 2010 Cosmetic Plastic Surgery Statistics. American Society of Plastic Surgeons website. Available at: http://www.plasticsurgery.org/Documents/news-resources/statistics/2010-statisticss/Overall-Trends/2010-cosmetic-plastic-surgery-minimally-invasive-statistics.pdf. Accessed June 17, 2011.

6. Miglioretti DL, Rutter CM, Geller BM, et al. Effects of breast augmentation on the accuracy of mammography and cancer characteristics. Journal of the American Medical Association. 2004;291:442-50.

7. Mammograms and Other Breast Imaging Procedures. American Cancer Society website. Available at: http://www.cancer.org/acs/groups/cid/documents/webcontent/003178-pdf.pdf. Accessed June 17, 2011.

What are Digital and 3D Mammograms?

With digital mammography, images are recorded and viewed on a computer rather than on photographic film. The digital images can be adjusted or enhanced for further evaluation. Although both film and digital mammography can effectively detect breast cancer, digital mammography may be better at detecting breast cancer in young women and those with dense breasts.3

Traditional mammograms (whether film or digital) provide a two-dimensional view of the breast. In February 2011 the US Food and Drug Administration approved the first imaging system that provides both two- and three-dimensional views (the Selenia Dimensions System). Radiation dose is increased with this system, but studies suggest that it may improve mammography accuracy and reduce the number of women recalled for additional imaging.4

Breast Cancer Before 50

If you talk with a woman with breast cancer, you will likely hear strong views in favor of early and regular screening mammography. These voices are worth considering as we make our own decisions.

For Heidi Stephens of Raleigh, North Carolina, a routine mammogram at age 46 led to a diagnosis of Stage II breast cancer. In addition to the cancer detected by mammography, additional testing with magnetic resonance imaging detected two other areas of cancer. “I had a mastectomy in February,” says Heidi. “The sentinel node was positive, so they took 10 more. The other lymph nodes were negative. I’m now in chemotherapy to make sure that it hasn’t spread microscopically.”

Heidi has no family history of breast cancer, and the diagnosis came as a shock. Asked what prompted her to continue being screened after the USPSTF guidelines came out, she replies, “I just knew my GYN would be mad if I hadn’t; I was going in for my annual, so I knew I had better have it done.

“I’m just grateful that they caught it,” she continues, “because if I’d waited until it showed up somewhere else, who knows what my prognosis would have been. Anybody who’s under 50, I tell them not to wait.”

Tammy Wilson of Apollo, Pennsylvania, was diagnosed with Stage IIIB breast cancer at the age of 38. After taking a fall while tubing, she noticed a breast lump that she initially thought was a bruise. A friend encouraged her to get it looked at, ultimately leading to what Tammy describes as “the 30-second phone call you wish you would never get.”

Her oncologist encouraged her to undergo genetic testing, and Tammy learned that she carried a BRCA2 mutation (an inherited gene mutation linked with a high lifetime risk of breast and ovarian cancer). It had never occurred to her that she was at high risk of breast cancer because the only breast cancer in her family that she was aware of involved her father’s mother. After her cancer diagnosis and genetic testing, however, Tammy learned of several other cases on her father’s side of the family.

Because of the BRCA2 mutation, Tammy had a bilateral mastectomy as well as surgery to remove her ovaries and fallopian tubes. Although she’s grateful that the cancer wasn’t detected any later, she wishes that screening had caught it earlier. Had she known of the BRCA2 mutation in her family, she would have been a candidate for earlier and more-intensive screening, but, as she points out, “How many people really know their family history?”

In addition to being a strong advocate for mammography, Tammy also sets an example for her two daughters by taking an active and positive role in her treatment and recovery. “At the moment of getting the phone call, I was a wreck,” she says. But as the day went on, her thoughts changed to I can stay sitting in a corner rocking or I can really take charge of it. This is my chance to shine.

Tammy has been open with her children and her community throughout this experience, and she hopes that she can inspire others to take care of themselves. “You never know when you’re going to be that trigger for someone,” she says. “Somebody might sit there and think Wow, this could happen to me. I need to be my own best advocate.”

Breast Augmentation and Breast Cancer Screening

Breast augmentation (use of implants to enlarge breasts) is the most common type of cosmetic surgery in the United States. In 2010 nearly 300,000 women underwent the procedure.5 The presence of implants can make it more difficult to detect breast cancer by mammography.6 Women with breast implants also require additional mammographic views, which increases the amount of time required for mammography and the amount of radiation delivered. Nevertheless, women with breast implants are advised to follow breast cancer screening guidelines.7