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Mammography: Let’s Calm Down, Check Math

November 28, 2011
Written by: , Filed in: Breast Imaging
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“I’m confused.”

That’s what Canadian breast cancer survivor Sherri Leclair said about the new recommendations by the Canadian Task Force on Preventive Health Care against routine mammography screening for women in their 40s and for screening every two to three years for women 50-74.

The American College of Radiology left no room for confusion regarding its opinion. On its Web site, the ACR headlined its response: “Canadian Task Force on Preventive Health Guidelines for Breast Cancer Screening Ignore Best Evidence and Would Cost Thousands of Lives Each Year.”

Unfortunately, the ACR hurt its credibility by flunking basic arithmetic. It justified the “thousands of lives” accusation by citing a study concluding that following such guidelines in the United States would lead to the deaths of 6,500 additional women each year. The ACR asserted that “a similar proportion” of Canadian women would likely die.

The U.S. population is about 312.7 million. Canada’s is about 34.6 million, or about 11 percent of the U.S. total. Eleven percent of 6,500 is 715, not “thousands.”

Unlike the ACR, Canada’s National Post newspaper took a thoughtful and balanced look at the issue. That article is the source of the “I’m confused” quote from Sherri Leclair, whose doctor suggested a mammogram when Leclair was 45 even though Leclair had no family history of breast cancer. The screening detected a tumor, which was removed via a lumpectomy.

“I feel I was the luckiest person in the world that I had that mammogram,” she told the Post. Still, she said she didn’t know what to think about what the Post called “the clash of expert opinions.”

The ACR refuses to acknowledge that those who disagree with it are experts. Said Barbara Monsees, MD, chair of the ACR Breast Imaging Commission, as quoted in the ACR response:

Panels without profound expertise in breast cancer screening should not be issuing guidelines.

OK, but should an organization with a profound conflict of interest be issuing guidelines? Or criticizing the guidelines of others? The ACR seems to be hurling stones from inside a glass house.

Meanwhile, the public, with varying degrees of exasperation, anger, and fear, says, “You’re supposed to be the experts, but all you do is argue among yourselves, so I don’t know what to believe.”

The Post quoted Eitan Amir, MD, of Toronto’s Princess Margaret Hospital as suggesting a focus on screening women most at risk, such as those with a family history of breast cancer or a genetic susceptibility.

Dr. Amir, an oncologist who specializes in treating breast cancer, said:

There is no doubt that breast screening works in a substantial number of patients. It also harms a substantial number of patients. If you’re involved in screening, you’re at risk.

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One Response to “Mammography: Let’s Calm Down, Check Math”

  1. Daniel on December 2nd, 2011 at 12:48 pm

    I appreciate Dr. Millburg’s concern over the mathematics, but he has lost sight of the numerous errors in analysis of the United States Preventive Services Task Force (USPSTF) guidelines as well as the Canadian Task Force. Dr.Millburg seems to be, naively, unaware of the fact that opponents of screening like Dr. Gotzsche, are funded through grants and donations to support their opposition, yet they are seen as “objective” with no conflict of interest. Both Task Forces were comprised of members who had no expertise in breast cancer screening. It is clear that they were “guided” by others to reach the “correct” conclusions. Had they had any expertise they would be aware of the fact that breast cancers do not “melt away” as is asserted in the papers on “overdiagnosis” upon which they relied. When did magic replace science? These papers were methodological nonsense. The fact that members of the USPSTF have refused to debate experts in breast cancer screening makes it clear that they do not have the knowledge to address the scientific concerns. I am certain that Dr. Millburg, as an expert in mammography screening, would agree that, if you are making guidelines that affect life and death decisions, you should be able to defend them against any and all concerns.

    By the way – since both Task Forces assert that they only relied on data from the randomized, controlled trials, which of the RCT stratified by risk proving that screening high risk women saves lives ? Opps – NONE. Screening only high risk women will miss 75-90% of breast cancers diagnosed each year with no proof that any lives will be saved. Forget about the math, get some fundamental knowledge before you spout off.

    ENOUGH IS ENOUGH

    Response To The Canadian Task Force On Preventive Health’s Guidelines For Breast Cancer Screening.

    Daniel B. Kopans, M.D.

    Professor of Radiology – Harvard Medical School
    Senior Radiologist – Breast Imaging Division – Massachusetts General Hospital

    With the publication of the Canadian Task Force On Preventive Health’s (CTFOPH) guidelines for breast cancer screening in the Canadian Medical Association Journal, it is now clear that opposition to mammography screening is all about saving money rather than saving lives. The CTFOPH admits that screening mammography save lives, but their rationale for advising against screening for women ages 40-49 and extending the time between screens for older women, is clearly based on cost. If there was no direct collusion with the United States Preventive Services Task Force (USPSTF), the Canadian Task Force admits drawing most of their information from the US group. Given that the USPSTF ignored major studies in Sweden and the Netherlands in their pronouncements, it is not surprising that the Canadian Task Force ignored the same major sources of information. Adding to the clear emulation is the accompanying article by Peter Gotzsche, in support of the Task Force guidelines. The USPSTF used Karla Kerlikowske for their supporting apologist ( ). Dr. Kerlikowske has been opposed to screening women ages 40-49 since at least 1993 when she, knowingly, used data grouping and averaging to make it appear that there was a sudden change in breast cancer detection at the age of 50 when her data clearly showed a steady increase with increasing age with no abrupt change at the age of 50 ( ).

    The Canadian Task Force is supported by Peter Gotzsche who has been opposed to breast cancer screening for over a decade, first violating the rules of legitimate trial analysis in 2000 ( ), and again in 2001 ( ) to conclude that there was no benefit from screening for women at any age. Dr. Gotzsche’s approaches have been refuted and repudiated by numerous analysts ( , , , ). Much of the misinformation on breast cancer screening has come from the so-called “Nordic Cochrane Center” headed by Dr. Gotzsche. Just recently a letter to the editor of the journal The Lancet, signed by more than 40 experts in breast health care from around the World, wrote that the Cochrane Center promoted an “active anti-screening campaign…based on erroneous interpretation of data from cancer registries and peer reviewed articles.”. The letter went on to state that “We consider the interpretation by Jorgensen, Keen, and Gotzsche, of the balance of benefits and harms [of screening] to be scientifically unsound” ( ), yet the US and Canadian Task Forces relied on much of this misinformation, and Gotzsche was chosen to write in support of the Canadian Task Force.

    What has permitted all this is the fact that the pendulum has swung too far. The use of “Task Forces” comprised of individuals who are chosen for their supposed lack of a conflict of interest, permits the use of behind the scenes “advisors” like doctors Gotzsche and Kerlikowske, who are not impartial, to guide the inexperienced Task Force members. This was clearly evident with the USPSTF where the members of the Task Force have been unwilling to debate the issues with any screening experts because the members, individually, lacked the expertise to defend their position. It is fairly certain that the same is true for this Canadian group as well. The fundamental fact is that if you do not have some “conflict of interest” you have no expertise in a subject and certainly should not be advising on life and death issues. The failure of this approach was clearly demonstrated by the 2009 United States Preventive Services Task Force that had only one member with any expertise in breast cancer screening and this resulted in, a scientifically, unsupportable set of guidelines ( ) whose implementation, using their own analysis, would result in tens of thousands of unnecessary deaths ( ). It did not seem possible that any review could top the amount of misinformation promulgated by the USPSTF, but, in fact, the Canadian Task Force has managed to outdo the USPSTF.

    It has been clear for years, and has been, repeatedly, documented in the scientific literature, that the age of 50 has no biological or scientific basis to be a threshold for screening. NONE of the parameters of screening changes abruptly at the age of 50 or any other age ( ). It is nothing more than an arbitrary number. The fact that the CTFPH continues to imply that it represents a legitimate threshold is simply perpetuating a lie. This is either due to gross ignorance of the data, or malicious intent. Although they make a brief comment about this, their review is predicated on the totally unsubstantiated concept that the age of 50 has any more importance than any other age when it comes to screening.

    Their emphasis on the fact that the “absolute” benefit of screening is higher among women 50-69 than it is for women 40-49 is grossly misleading. They failed to point out (or they failed to understand) that the incidence of breast cancer increases steadily with increasing age. This is paralleled by the mammography detection rate which increases steadily with increasing age and with the amount of breast cancer in the population. This means that the absolute number of women diagnosed with cancer each year will be higher for any group of older women than any group of younger women at whatever age you choose to make a dichotomous analysis (assuming the same number of women at each age). In addition, by averaging the numbers for women in one decade (ages 40-49) and comparing them to the average for women in two decades (50-69), the dichotomous difference is exaggerated. This is statistics 101 which both Task Forces, apparently, slept through. In fact, had the Task Force been honest, they would have pointed out that the percentage of newly diagnosed breast cancer cases in Canada is almost the same for women at each decade of life. Women ages 40-49 account for 20% of newly diagnosed breast cancers. Women in their 50’s account for 25% while women in their 60’s account for , 27%, and 28% were among women in their 70’s and older. It is merely deceptive to compare women in one decade of life to all the others averaged together. Furthermore, although absolute numbers are important, the Canadian Task Force ignored the very important calculation of the number of years of life lost to breast cancer. In fact, women ages 40-49 account for more than 40% of the years of life lost to breast cancer due to premature deaths (younger women have a longer life expectancy).

    The errors by the Canadian Task Force are amplified by the fact that they chose to rely on the selected review of the literature thorough 2008 that was compiled for the USPSTF. As a consequence, since the USPSFT ignored important population data from Sweden ( , , , ) and the Netherlands ( , ), the Canadian Task Force was also unaware of the fact that mammography screening is the main reason that deaths from breast cancer have declined over the past 20 years, and that the decrease in breast cancer deaths due to screening is closer to 30% and not the 15% used by the Task Forces in their calculations. Without having experts in breast cancer care, there was no way for the Task Forces to realize that, although therapy has improved over the past years, it is still a fact that therapy only saves lives when breast cancers are found early.

    The Canadian Task Force was concerned about “overdiagnosis” leading to “overtreatment”. They seem to fail to understand that mammography screening does not cause overdiagnosis, but rather it is pathologists who are unable to determine whether a cancer (of any kind) will be lethal or not. Treatment is decided by oncologists. Finding cancers early and saving lives should not be faulted. Before there was any kind of systemic therapy, not all women died from their breast cancers. Even now, were we to ignore mammographically detected cancers, the majority of women with clinically evident (palpable) cancers do not benefit from their therapy. Many women with palpable cancers will be cured by removing them with no additional therapy, while others are destined to die regardless of the treatment (it is for these latter women that earlier detection makes the difference). It is only a small number of women with palpable cancers who do benefit from systemic therapy, but, because it is not possible to, accurately, determine who these women are, thousands of women must be treated to benefit a few. Would the Task Force seek to end adjuvant therapy since so many women are treated “unnecessarily”? Unfortunately, approximately, 40,000 women die each year from breast cancer in the U.S. The majority of these women were treated for their cancers. Using the Task Force rationale, these should be considered as having had “unnecessary” overtreatment since these women derived no benefit from the treatment. Would the Task Force suggest that we stop treating women for breast cancer because we cannot, as yet, determine who will truly benefit and who will not? Should we not treat bacterial pneumonia with antibiotics because we do not know who will recover without them, who will die despite them, and who may develop a superinfection or adverse reaction because of them? By this rationale all therapeutic interventions should stop.

    One has to question their literature search when they state that “No primary studies looked at the risk of overdiagnosis” In fact there are studies that have looked at this in the only, scientifically, legitimate fashion, using the RCT, and these have suggested that overdiagnosis occurs less than 10% of the time ( ) and likely less than 1% of the time ( ). The studies on overdiagnosis that were used by the Task Force and referenced by Dr. Gotzsche were methodologically unsupportable. The fact that they were published is a failure of peer review rather than their validity. A simple example is in Gotzsche’s reference to an article by Autier et al ( ) where registry data were viewed by “analysts’ outside of the Netherlands to conclude that screening had not played a role in the decrease in deaths in that country. This paper, that was methodological nonsense, was promoted by the media. Ignored were analyses by investigators in the Netherlands, looking directly at patient data, that concluded that screening was the primary (16) and increasing reason for the decline in breast cancer deaths in that country (17). The problem is that both the US and Canadian Task Forces simply accepted scientifically unsupportable analyses without doing what they should have done which was to critically assess the publications before accepting their conclusions.

    Their suggestion that “studies involving older women have estimated
    that the frequency of overdiagnosis ranges from 30% to 52%.” is based on pseudoscientific publications that were methodologically nonsense. These papers suggested that mammographically detected breast cancers would “melt away” if left alone, yet there are virtually no cases reported in the literature of breast cancers “melting away” ( ). This ridiculous argument, that has no scientific foundation, has now been reinforced by a group that clearly has no expertise, but is given the mantle of an expert review.

    The Canadian Task Force is correct on one fact. There have been no good trials that have, directly, analyzed the importance of the time between screens, but there needs to be some reason, logic, and common sense. Does the Task Force really believe that breast cancers do not grow and that the likelihood of metastatic spread is not related to the size of the cancer and the length of time it has been growing in the breast? Why would they think that it is a good idea to wait for two to three years between screens? Studies have clearly shown that cancers are smaller and at a lower stage when screening is every year instead of every two years. Even the USPSTF clearly stated that more lives would be lost by biennial screening compared to annual mammography. It appears that both groups have no problem with unnecessary deaths.

    The USPSTF opposed screening mammography for women ages 40-49, and opposed teaching women breast self examination (BSE), but, because they have such a strong association with the American College of Physicians, the USPSFT left clinical breast examination (CBE – a test performed by primary care physicians for which they are reimbursed) open by suggesting that the data were insufficient to decide for or against (meaning it could still be practiced). The CTFPH, however, went further and stated that there was no evidence of benefit for CBE. This was another example of members of the Canadian Task Force’s failure to understand the data. Although it is likely that CBE only has a value when it is the only available test and cancers present as large (2 cm. and over) lesions, there was, in fact, a randomized, controlled trial that showed this. The Health Insurance Plan of New York (HIP) Trial did not separate the benefit of CBE from the benefit of mammography. Both were performed annually on the study group leading to a 23% decrease in breast cancer deaths ( ). In the circumstance where the control cancers are very large, earlier detection by CBE could reduce deaths. The failure of the CTPFH to be aware of this fundamental information is of great concern, confirming a lack of fundamental knowledge among the, supposed expert, Task Force members. Should the lives of women be determined by a group that didn’t even know the results from one of the RCT of breast cancer screening?

    The Canadian Task Force also advised against breast self examination (BSE). One has to wonder if they stopped to consider the consequences of their advice. If the Task Force opposes mammography screening, and they oppose CBE and BSE, what is their advice to women in their forties? “Wait until you can no longer ignore the lump in your breast (perhaps when it grows through your skin), and then come in and your doctor can initiate palliative care”. Is this the kind of insane guidance our “Task Forces” should be providing? The death rate from breast cancer has declined in the United States by over 30% since the initiation of mammography screening at a National level in the mid 1980’s ( ). More than 100,000 lives have been saved by early detection since 1990. What these brilliant Task Forces are suggesting is a return to the death rate of the 1950’s.

    Both the US and Canadian Task Forces were completely occupied with their concern over “unnecessary” additional imaging, and biopsies for what prove to be for benign lesions. The Task Force was clearly unaware that there is a higher rate of “benign” biopsies when women wait until something is palpable ( ). They also are unaware of the basic fact that when cancer is diagnosed when it is palpable, the size and stage are larger and later than cancers detected by mammography. To avoid “unnecessary” biopsies, the Task Force should simply advise against all breast biopsies and simply let breast cancer run its course. This would save countless women all these, “unnecessary” interventions.

    There is clearly an agenda behind all of this. Why was Peter Gotzsche, a longtime opponent of mammography screening whose non-scientific analyses have been, repeatedly, refuted by multiple authors, chosen to write the accompanying editorial? Dr. Gotzsche suggests that supporters of screening wish to perpetuate the status quo. It is certainly clear that supporters of screening support science over agendas. Mammography screening has fulfilled all the requirements of an efficacious test. It finds cancers at a smaller size and earlier stage. Its use results in a, statistically significant, decrease in breast cancer deaths in randomized, controlled trials, and when it is introduced into general population use, the rate of breast cancer deaths declines. There is not much more that can be done to prove its efficacy. One has to ask what is behind the persistent effort to reduce access for women to screening.

    Both Task Forces openly admit that lives will be lost by following their guidelines. Why were they more concerned about having a few (unnecessary) extra mammographic views than they were about the unnecessary deaths that would be the result of their guidelines? These Task Forces were, clearly, not interested in women’s health. Any one woman is screened only once a year so the “number needed to screen” (NNS) (which both Task Forces grossly overestimated) has little importance for her. NNS is merely a surrogate for the cost of finding breast cancer. It is now clear that these Task Forces were more interested in saving money rather than saving lives. It is time for the charade to stop. Those who oppose mammography screening should state clearly that they do not believe that it is worth the cost to save lives. At least this would be honest, and women could have a legitimate discussion about how much their lives are worth. The incredibly dishonest effort to deny women access to screening through pseudoscience is shameful. Everyone now agrees that lives are saved by screening beginning at the age of 40. Experts can provide their analyses of the data and this can and should be debated at a scientific level, but the decision whether or not to participate in screening should not be made for women. It seems incredible, in the 21st century, to have to argue that women should be allowed to make the decision for themselves.