June 2011

Dr. Oz, Thyroid Shields & Mammography — The Popular TV Host Sparks a Debate With Radiology
By Kathy Hardy
Radiology Today
Vol. 12 No. 6 P. 18

The latest controversy surrounding mammography comes from an unlikely source—a cardiovascular surgeon with his own syndicated television show. Mehmet Oz, MD, an Oprah Winfrey protégé and host of The Dr. Oz Show, started a debate over whether radiation exposure from mammography could be causing an increase in thyroid cancer when he recommended that women wear lead thyroid shields when getting their mammograms.

During a September 2010 segment of the popular medical advice program, Oz associated the findings from a study involving dental x-rays with the amount of potential radiation exposure stemming from screening mammograms, suggesting the two procedures may account for part of the increase in thyroid cancer among women and calling it “the fastest growing cancer in women.”

Recommendation Without Data
“There has not been any data on this, but personally, if I was getting a mammogram, I would use [a thyroid shield] too,” Oz said in the episode. “Because [of] the amount of radiation exposure, although it’s very small in mammography, it’s not that dissimilar from dental x-rays.”

The show was rebroadcast in December 2010 and apparently Oz’s recommendation went viral in the form of an e-mail with the subject line “Precautions re Mammograms and Dental XRays/A Useful Warning.” The e-mail message cites The Dr. Oz Show and retells the story of a woman who said she never would have known to ask for a thyroid shield when getting her mammogram if it hadn’t been for the show.

The topic also made its way onto blogs and social networking sites, sparking discussion about the topic. The issue of thyroid shields for mammograms even surfaced on the rumor-busting website Snopes.com, where the source of the rapidly spreading e-mail, tweet, and blog message is credited to The Dr. Oz Show. The site details statements on the topic made since the initial Dr. Oz Show, concluding that “in general, the soundest advice for those concerned about exposure during x-ray procedures is to discuss their concerns with their healthcare providers prior to such procedures and determine what level of protection the situation merits.”

The radiology community responded to the December rebroadcast with a joint statement from the ACR and the Society of Breast Imaging (SBI), referring to “an erroneous media report that the small amount of radiation a patient receives from a mammogram may significantly increase the likelihood of developing thyroid cancer. This concern simply is not supported in scientific literature.”

 “Correlation is not causation,” says Constance Lehman, MD, PhD, director of imaging at the Seattle Cancer Care Alliance in Washington and a professor of radiology at the University of Washington. “Screening mammography is not an area where there should be a concern that this imaging exam causes significant harm to the patient. It’s not good science.”

For women who get mammograms every year, this debate may not sway them away from this routine. However, some in the radiology community believe the discussion surrounding the issue may keep some of the approximately 32% to 39% of women (mammography rates vary by race, according to the Centers for Disease Control and Prevention) from having a mammogram.

“This gives women another reason to question whether or not they need a mammogram,” said Phil Evans, MD, director of the University of Texas Southwestern Center for Breast Care, while a guest on a “rebuttal” episode of The Dr. Oz Show in April of this year.

“All these little controversies are dissuading women from having mammograms,” added Daniel B. Kopans, MD, a professor of radiology at Harvard Medical School and director of breast imaging at Massachusetts General Hospital, another guest on the April episode.

In both episodes, Oz made a point of saying that women should get mammograms, noting that they save lives but adding that “we have a suspect history of exposing people to radiation.”

“If you want women to get mammography, do everything you can to make it safe,” he said during the April show.

He went on to implore women to speak up for their right to ask for a thyroid shield when getting a mammogram, saying, “It’s about your right to control your care.”

Kopans says it is too early to determine the large-scale effect of Oz’s statements regarding thyroid radiation from mammography. At the breast imaging center at Massachusetts General, a few women coming in for mammograms are asking for thyroid shields each day; however, he has not seen any detectable decrease in patient volume.

“I do not have any data from any of the centers, but here and around the county, some women are asking for the shields,” Kopans says. “Here we are explaining that they are not necessary and could compromise the mammogram, but we have them if the patient insists.”

On the show, Kopans differentiated mammography from dental x-rays by explaining that x-rays are like a spotlight. In a darkened room, a spotlight would illuminate only the area at which it was directed. Similarly, x-rays are confined to a specific area.

“The thyroid may be ‘illuminated’ during dental x-rays, but there is no radiation to the thyroid during a mammogram,” he says.

Minute Risk
Kopans explains the only radiation that reaches the thyroid during a mammogram is scatter and that studies show this scatter radiation amount is equivalent to 30 minutes of background radiation that people receive every day from the environment.

“During [Oz’s] one-hour show, we were all receiving twice the dose, from background radiation, that the thyroid might receive from a mammogram,” he says. “This means that a woman could have a mammogram every year for 40 years and her thyroid would receive less total radiation than it receives from one day of background radiation.”

Statistics cited in the ACR/SBI press release show that for annual screening mammography for women aged 40 through 80, the cancer risk from the amount of radiation scattered to the thyroid during a mammogram is “incredibly small,” measured at less than one in 17.1 million women screened. They stress that this “minute” risk of thyroid cancer be balanced with the fact that using a thyroid shield could impact the quality of the mammography image, interfere with the diagnosis, and ultimately result in the need for a second mammogram.

“As we told Dr. Oz, it was not just the fact that a thyroid guard was unnecessary and could compromise the mammogram, the concern is that misinformation over inconsequential issues will discourage women from participating in screening and its potential to save lives,” Kopans says.

While on the show, Evans showed a mammogram image where the patient was wearing a thyroid shield. In the image, viewers could see where the shield slipped down into the field of view, blocking some of the breast and necessitating a repeat mammogram, exposing the patient to more radiation. Another doctor on the April show, Jocelyn Rapelyea, MD, associate director of breast imaging at the Breast Imaging and Intervention Center of George Washington University, explained that since the initial Dr. Oz Show episode, many patients visiting her practice for mammograms had asked for shields, necessitating repeat views 20% of the time.

Although Oz said thyroid cancer is the fastest-growing cancer in women, Kopans noted that cancer of the thyroid is increasing with the same rapidity among men. As the radiologist noted during the program, “Unless men are sneaking in at night to have mammograms, mammography had nothing to do with the increasing incidence of thyroid cancer.”

Imaging’s Message
“The bottom line was that there was no risk to the thyroid with mammography, so a shield was not needed and that it could compromise optimal imaging,” Kopans says. “Dr. Oz dismissed the compromised imaging, suggesting that we often didn’t understand risk until many years later and that he was going to stick with his recommendation.

“Our recommendation is that we will provide a thyroid shield if a patient asks,” he continues, “but it is totally unnecessary and could compromise optimal positioning and lead to the need for repeat exposures.”

This isn’t the first time radiologists and women’s health professionals felt the need to defend and promote the benefits of mammography as a screening tool for breast cancer. Since the 1970s, when mammography became the standard screening method for breast cancer, the practice has come under attack, says Carol H. Lee, MD, a diagnostic radiologist at Memorial Sloan-Kettering Cancer Center in New York and chair of the ACR’s Breast Imaging Commission. During the 1990s, the American Cancer Society, with support from the ACR, aggressively promoted the benefits of screening mammography, running advertisements on television and in magazines informing the public of the importance of this method of breast cancer screening. At that time, there was some feedback stating that mammography was being “oversold,” she says, “although how can you oversell something that’s proven beneficial?”

Defending Mammography
“I don’t understand what the motivation is [for arguing against mammography],” Lee adds. “We have a test that has been studied and proven to detect breast cancer and reduce mortality, yet it continues to face challenges.”

In 2009, recommendations regarding breast cancer screening from the U.S. Preventive Services Task Force (USPSTF) stirred controversy by withdrawing its recommendation for routine screening mammography for women aged 40 to 49. This recommendation reversed the task force’s 2002 recommendations for breast cancer screening beginning at age 40. The task force also concluded in the 2009 recommendations that the decision to start regular biennial screening mammography before the age of 50 should be an individual choice between a woman and her doctor, taking into consideration specific benefits and harms. The benefits of early breast cancer detection should be weighed against the potential harm of a false-positive finding or the increased exposure to radiation, according to the task force.

Within a matter of days, imaging and women’s health organizations spoke out against the 2009 USPSTF recommendations and to date, gynecologists and radiologists continue to recommend that women begin screening mammography at age 40.

“The ACR and the SBI reviewed the USPSTF analysis and found that this group of individuals lacked expertise in breast cancer care and failed to understand the fundamental scientific evidence and that there guidelines would result in numerous lives being lost that could be saved by annual mammography,” Kopans says. “A recent review concluded that, among women now in their 30s, as many as 100,000 lives would be lost unnecessarily to breast cancer by following the USPSTF guidelines.” Concerns continue regarding the impact of this latest mammography controversy and the potential setbacks in early breast cancer detection it could cause.

“My greatest concern is the large number of women who are not undergoing regular mammograms because of issues like this, leaving them at risk for a delayed diagnosis of breast cancer,” says Lehman. “We are working hard to make sure all women age 40 and older are undergoing mammography so that if they have breast cancer, we can find it early when they can still be cured.”

— Kathy Hardy is a freelance writer based in Phoenixville, Pa. She is a frequent contributor to Radiology Today.