Don’t Let Flawed Studies Guide Screening Mammo Decisions, Experts Say

April 2, 2014

Mammography screening for breast cancer saves lives: this should be the message that physicians spread to colleagues and patients, say leading experts.

Are too many women getting mammograms unnecessarily?

This question has been increasingly raised as concerns over the effectiveness of mammography to prevent breast cancer deaths have been debated. The latest iteration came in February when the 25-year update to the Canadian National Breast Screening Study was published in the British Medical Journal. The study concluded that annual mammography in women aged 40 to 59 years did not reduce breast cancer deaths beyond that of physical examination.

Still, among leading American policy and women’s health organizations, the answer to whether mammograms are being overused is a resounding “NO!” [[{"type":"media","view_mode":"media_crop","fid":"23760","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_5554098312277","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"1962","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"line-height: 1.538em; float: right; height: 153px; width: 230px; margin: 10px;","title":" ","typeof":"foaf:Image"}}]]

Instead, experts lament stagnate screening rates and fear that the message of mammography’s benefit is being lost in the conversation, with physicians steering clear of what has become a somewhat contentious debate.

The American College of Obstetricians and Gynecologists (ACOG), the American Cancer Society, and the American College of Radiology all criticized the results of the Canadian study. They pointed to flaws in the screening technology employed, trial design, misleading analysis, incomplete reporting in the general media, and a failure by those embracing the study to remember other major mammography trials that have pointed to a vastly different conclusion.

“I think because screening trials and data are complex that to truly glean meaning from them you have to dig down into the details,” said Richard Wender, MD, chief cancer control officer, American Cancer Society. “The way the media has portrayed the results is to say the study defines the science rather than letting the science dictate how women should respond and behave.”

One particular point of contention with the Canadian study is that the quality of the mammography machines used in the study are outdated and poor, explained Carol Lee, MD, chair of the American College of Radiology Breast Imaging Communications Committee. The images produced by the older technology were cloudy and made it more likely for cancers to be missed by radiologists, she said.

“Paying a lot of attention to the Canadian study is, to me, analogous to relying on a weather report from last week to tell us if it is raining outside today,” Lee continued.

For example, the study results indicated that 66% of the women had more advanced tumors that were big enough to be felt on physical exam at the time of mammography screening. “With modern mammography screening today, only 15% of breast cancer tumors can be felt; this means that more early-stage tumors that are missed by clinical breast exams are caught by mammograms when they are very small and more easily treated,” ACOG pointed out in a statement issued after the Canadian study was published in BMJ.

In addition, the Canadian study results were already an outlier when first reported, Wender said.

“Frankly, it didn’t provide any new information that wasn’t already known,” he said. “When we’ve had a study that has already shown no benefit, the likelihood that a benefit would emerge on follow-up analysis is just about zero.”

Furthermore, despite being an outlier, Wender pointed out that the study was considered and included in meta-analysis used by the American Cancer Society and the U.S. Preventive Services Task Force in providing guidelines for mammography. ACOG also included the study in forming its recommendation for annual mammography to commence at 40 years of age in women at average risk for breast cancer. ACOG reiterated its stance in its statement.

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Still, the public reaction to the study is troubling and means primary care clinicians must be clear in continuing to support the need for routine mammography, Lee said.

Already the American Cancer Society has tracked a dip in screening rates from a high of 70% in 2000 down to a steady 67% from 2005 to 2010, according to data published last year.

The need for better communication is especially important when discussing mammography with women in their 40s, Wender said. That’s due to the U.S. Preventive Services Task Force’s stance that women aged 40 to 49 years talk to their health care providers to weigh the risks and benefits of mammography in order to make an informed decision about when to begin screening, he said.

“The swirl of controversy may have zapped some energy from primary care providers doing informed decision-making,” expressed Wender.

His fear is that informed decision-making may not be taking place and, instead, women who are hesitant about mammography may simply be putting it off without truly weighing the risks and benefits.

Jennifer Harvey, MD, head of the University of Virginia Medical Center’s Division of Breast Imaging and director of the UVA Breast Program, echoed the concern that the important conversations about mammography might be getting lost as primary care providers seek to get through high daily volumes of patients.

“The physicians-the primary care doctors, including the ob/gyns-are the ones who are going to drive it,” Harvey said. “And if you ask a woman why she hasn’t had a mammography, the most common answer is, ‘Because my doctor never told me to get one.’”

Grand rounds to physician colleagues help drive the message, Harvey said, but she admitted that more needs to be done to ensure the message isn’t being lost. To that end, Wender reported that the American Cancer Society is planning to improve its public communication efforts surrounding mammography.

The society is already in the process of writing new guidelines for mammography, continued Wender. “Once done, we are going to enthusiastically promote what we recommend,” he said. “There is no chance we won’t recommend mammography at some interval for women in their 50s, and it will likely be similar for women in their 40s. But whatever it is, we are going to enthusiastically promote it to re-energize the public.”

In the meantime, Harvey said physicians must take the lead in starting the conversation with women and recommending routine mammography. Some women will come armed with the latest media reports and ready to challenge the need for mammography, she said. But the more likely scenario is the woman who comes for a routine exam and exits the room without ever broaching the topic of mammography.

“The message must be consistent,” continued Harvey. “Mammograms save lives.”