New Mammogram Guidelines for Women

Regular mammograms to screen for breast cancer is the status quo for women in their forties. A new set of guidelines being released on Tuesday by the American College of Physicians (ACP) is trying to fine-tune that screening process.

According to the recommendations, appearing in ACP's peer-reviewed journal, Annals of Internal Medicine, mammography screening decisions for women 40 to 49 should be made on a case-by-case basis, with a woman's individual cancer risk and preference taken into account.

The guidelines make four recommendations for physicians and female patients in this age range:

1. Doctors should periodically perform individualized assessment to help guide decisions about screening mammography.

2. Doctors should inform women in this age group about the potential benefits and harms of screening mammography.

3. Doctors should base screening mammography decisions on benefits and harms of screening as well as a woman's preferences and breast cancer risk profile.

4. ACP recommends further research on the net benefits and harms of breast cancer screening modalities for women in this age group.

According to Dr. Douglas K. Owens, a researcher with Veterans Affairs Palo Alto Health Care System and professor of medicine at Stanford University School of Medicine, who chaired the committee that developed the guidelines, "the general summary is that we are recommending that physicians should periodically assess individual woman's risk of developing breast cancer and that screening mammography decisions be made on the basis of a conversation between women and their clinicians that addresses the woman's risk of breast cancer, her concerns and preferences about breast cancer and screening, and the benefits and harms of screening mammography."

Breast cancer is the second-leading cause of cancer-related death among women in the United States, but the five-year risk for women in this particular age group has a large range, from 0.4 percent to 6 percent depending on risk factors.

An individualized assessment should review higher-risk factors including family history of breast cancer, older age at time of first pregnancy, younger age at time of first period and a previous biopsy.

The benefits include a mortality rate reduction of 15 percent after 14 years of follow-up. The authors of the study note that is significantly smaller than the 22 percent reduction seen in women fifty years or older.

Owens points to a recent study, published in The Lancet in late 2006, supporting the fact that breast rate mortality is lowered, although, he adds, "the estimates from randomized trials are modest."

But Dr. Robert Smith, director of cancer screening for the American Cancer Society (ACS) asserts that the benefits greatly outweigh the risks for women under 50. "In general, comparing women aged 40 to 49 to those 50 and over obscures the scientific evidence showing a gradual improvement in the effectiveness of mammography as women age, and as a result minimizes the apparent benefits of mammography in this age group."

The authors also analyzed data regarding the risks of mammography screening for women in their forties, and identified the potential harms of screening, including radiation exposure, procedure-associated pain, false-positive results, and over-diagnosis.

But the analysis found no direct evidence for most of these potential risks, except for false-positive results. "False-positive results are the most common risk. Various studies have shown that about one-third to one-half of women would receive a false positive result if they received annual screening from 40 to 49," Owens said.

Dr. Lynne Kirk, president of ACP, said she agrees that false-positive results are significantly harmful for this age group. "It does create a lot of anxiety even if the mammogram is just abnormal. Although for most women in this age group it doesn't turn out to be cancer, when it happens to you, you automatically think you're the one who has cancer. That's more common in younger women," Kirk said.

The ACS does not feel that the false-positive results act as a deterrent to women to be screened. Smith pointed out, "the discussion does not acknowledge that the difference in the false positive rate improves gradually over time, and is higher in all ages on the first mammogram than on subsequent mammograms. Recent evidence shows that most women are aware of false positives and seem to view them as an acceptable consequence of screening mammography when considered in the context of the benefit."

The new guidelines by the ACP emphasize that the research for breast cancer mortality reduction is simply not clear-cut, and while there is a benefit, yearly mammograms should not be a blanket recommendation without a discussion between the doctor and patient.

The ACS maintains most women have thought about the risks and benefits of mammogram screening, and will still choose yearly mammograms.

The last recommendation acknowledges the jury is still out, and more research needs to be done. "We have a lot of information on women over 50, so that makes this group more important for research," Kirk said. The authors of these guidelines hope more research will be done on the benefits and the risks, so physicians will have even more information available to offer their patients during these discussions.

"If a woman decides that the benefits outweigh the risks, we fully support her decision to get a mammogram," Owens said. "If a woman decides she wants to defer mammography, we recommend that she and her clinician readdress this decision every 1 to 2 years."