Screening and cancer: the controversies are spreading


As we have suggested before in these reports, the question of whether mass, population-based screening for certain cancers (including prostate cancer) is really the best strategy for prevention of risk from the disease itself is a complex one.

A new article, published this week in BMJ, addresses this issue with specific focus on the use of mammography in mass, population-based screening for breast cancer. The full article is available on line, and we would suggest interested readers consult that full article rather than the summary media reports that have been flying around in the past 24 hours.

In this article, Jørgensen and Gøtzsche report their estimate of the extent of “overdiagnosis” (the detection of cancers that will not cause death or symptoms) in publicly organized breast cancer screening programs.

“Overdiagnosis” is not a term we like. It is loaded with the implication that the diagnosis was unnecessary. What the term really means, however, is that such a diagnosis presents a high risk of unnecessary treatment because of bias on the part of physicians and patients that every cancer — once diagnosed — must be aggressively treated. We do need to start to understand that a finding of cancer cells is not necessarily sufficient to make treatment a clinical imperative. Why? Because excessive treatment comes with serious potential for harm. In the case of breast cancer it is not unusual today for women with no family history of breast cancer and no known specific risk factors to have a double mastectomy after a finding of very early stage breast cancer (a condition called “ductal carcinoma in situ” or DCIS). In the vast majority of cases, there is no more reason for this than there would be to carry out a radical prostatectomy in a man with high-grade prostatic intraepithelial neoplasia (HG-PIN). But look at the emotional and physical cost for an unknown clinical benefit.

Anyway, the new article is a highly detailed review of  findings on the diagnosis, management, and outcomes of treatment of women identified with breast cancer in five different populations (from the United Kingdom, Canada, Australia, Sweden, and Norway). It uses highly defined epidemiologic modeling systems to analyze the available data. And it comes to a very simple conclusion:

  • 52 percent of all cases of breast cancer diagnosed in populations offered organized mammography screening are forms of breast cancer that will not cause either symptoms or death.

This has been translated (by the authors, not by the media) into the statement that:

  • One in three cases of breast cancer is overdiagnosed.

Interestingly, this is approximately the same as the risk of “overdiagnosis” of prostate cancer currently observed in the USA.

The “New” Prostate Cancer InfoLink does not believe that, as a consequence of these data, we should start screaming that breast cancer screening is unnecessary or excessive or unwise. To the contrary, what these data imply is that mammography does not tell either a patient or her doctor whether the cancer that is being observed actually presents clinical risk. Just as with prostate cancer, it is becoming clear that we need tests that can help doctors and their patients differentiate between clinically significant and clinically insignificant forms of breast cancer based on the biologic characteristics of the cancer and the age and health of the patient.

The other thing that has to happen here is that — as a society — we need to start understanding the massive difference between a finding of some cancer cells and a diagnosis of a clinically significant cancer. We have tended, for the last 30 years, to assume that these are the same thing, and to treat every finding of cancer aggressively. It is time for us to start to use the knowledge we already have to think better about risk. In prostate cancer, active surveillance is a clear potential pathway to use the knowledge we have — and a similar strategy can be applied in the case of breast cancer too.

There are enormous emotional and psychological factors at play in all of this. It may not seem “rational” to large numbers of people not to treat some cancers aggressively. And that alone is one of the reasons why we will never overcome the problem of overtreatment without really good tests to help us separate the wheat (the truly clinically significant forms of cancer) from the chaff (the cancers that will never cause symptoms or death). The immediate and the long-term implications for cancer screening (at least in the cases of breast and prostte cancer) are vast.

4 Responses

  1. Well said!

  2. This article on MSNBC has quotes from Dr. Jorgenson and Dr. Brawley:

    “This information needs to get to women so they can make an informed choice," Jorgensen said. "There is a significant harm in making women cancer patients without good reason.”

    However, according to the Boston Globe, Dr. Otis Brawley, chief medical officer for the American Cancer Society, wrote in an e-mail that there is evidence that lives are saved through breast cancer screening. “Screening using mammography and clinical breast exams reduces the risk a woman will die of breast cancer by up to 35 percent,” he said.

    The European study on prostate cancer lowered the death rate by 20%. The Tyrol study showed an even great reduction in deaths for prostate cancer.

    Unfortunately what the American PLCO study showed was that a formal screening program did no better than current clinical practice. 50% or more of the men in the control group got screened. This seems to be the same as what this study showed. But this is what Dr. Brawley is focused on in his recent comments about prostate cancer.

    I guess what bothers me the most is the politics of cancer.

    IF there is a two-layer program, screen for breast cancer: OK and screen for prostate cancer: not OK, then I think both sides lose. The issues are the same, over-diagnosis, over-treatment, and harms to both groups. At the same time, some men and women have their cancers identified earlier and probably have longer lives because of that. I can think of individual cases of friends with breast cancer and with prostate cancer who have probably had extended good lives because their cancers were detected early and they were able to get good treatment. Is there bias here? Probably. It is human to fight for what we have believed and fought in favor or against for a long time. Is that good? No.

    What I wish would happen is that individuals in power would be open and take new information into account when making decisions. Public screening for both breast and prostate cancer may not be good things unless possibly they are focused in on at-risk communities. Early detection of clinically significant cancer for both breast and prostate cancer should be the ideal. Doctors should be trained to do a differential diagnosis as best as they can. We need to develop an education program that not all cancers kill to minimize the public reaction to do invasive treatment early.

    Will this happen? I hope so but based on the press we have been seeing, I don’t think so. Based on what Otis Brawley has said recently, prostate cancer and breast cancer will be addressed differently. I am mostly concerned that what will happen will harm both sides. Women will be harmed by over-treatment and I am very concerned, because of all the publicity, that men will lose insurance coverage for PSA/DRE for undiagnosed prostate cancer.

    One of the differences is that women are more likely to be activists. Women get upset when they believe that something works against their good and they take action, while fewer men react the same way.

    My rant is over. I am just one very small individual and one very small voice in the conversation.

  3. Sitemaster, another well balanced viewpoint.

  4. You are NOT one very small individual nor one very small voice, Kathy. You have been a caring advocate whose research and knowledge has educated many for several years.

    Yes, the controversy will continue. Yet, and I am repeating myself several times over, until another test/examination is determined to be better than the combination of PSA and DRE and approved by Medicare as more appropriate, the combination of PSA and DRE remains the reasonable method of identifying developing prostate cancer. And again, repeating myself as in past posts, the major onus is on the diagnosing physicians to thoroughly explain the extent of cancer diagnosed and, if low grade, low percentage cancer is evident, active surveillance (AS) should be encouraged. However, if past experience continues to dictate, this is not likely to be what most urologists and radiation oncologists recommend. On the other hand, if AS is explained and the patient then makes the choice for treatment, that is not “over-treatment” but rather patient choice.

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