More data that will cause controversy in the screening debate


Data from a very large, 25-year-long, randomized, controlled trial of screening for cancer has cast further doubt on the value of mass, annual, population-based screening as a way to reduce cancer deaths.

The “New” Prostate Cancer InfoLink wishes to be very clear, immediately, that this study does not — in our opinion — justify the conclusion that “no one should be tested” for cancer, or for prostate cancer in particular. It does, however, add to the database of information suggesting that most people do not actually benefit from mass, annual, population-based screening initiatives … because such initiatives do have a tendency to result in over-treatment of people with low- and very low-risk disease  but they do not necessarily lower risk for cancer-specific mortality.

Having stated that, the new study is not a prostate cancer study. It is a breast cancer study. The full text of the paper by Miller et al. can be downloaded from the web site of the British Medical Journal, and it is discussed in detail in an article in today’s issue of The New York Times.

Because this is a breast cancer-specific screening study and not a prostate cancer-specific screening study, we are not going to get into the details of the findings. Suffice it to say that with 15-year follow-up of data from a study cohort of just under 90,000 Canadian women aged between 40 and 59 years of age, who were randomized to receive either annual mammograms for a period of 5 years or no mammograms during the same 5-year period, the study’s primary conclusion was that

Annual mammography in women aged 40-59 does not reduce mortality from breast cancer beyond that of physical examination or usual care when adjuvant therapy for breast cancer is freely available. Overall, 22% (106/484) of screen detected invasive breast cancers were over-diagnosed, representing one over-diagnosed breast cancer for every 424 women who received mammography screening in the trial.

These data certainly seem to bear a close relationship to data regarding the risks and benefits of annual, mass, population-based screening for prostate cancer, and there is no doubt whatsoever that the underlying hormonal biology that drives risk for breast cancer in women and prostate cancer in men has many similarities.

The “New” Prostate Cancer InfoLink is by no means “against” the testing of men for risk of clinically significant prostate cancer (or of women for risk of clinically significant breast cancer) in an appropriate manner. What we have never countenanced, however, is the idea that every man needs an annual PSA test (or that every woman needs an annual mammogram). We do not believe that available data support either of these forms of mass, population-based screening, and we believe that the medical community needs to develop more sophisticated, and personalizable, risk-based forms of assessment that can differentiate between those people who do need frequent and regular testing because they are at demonstrably elevated risk and those who may need testing on a much less frequent basis because their risk level is demonstrably lower than average.

We know that less frequent testing for risk of colon cancer is highly effective as a screening mechanism. Customary screening protocols for risk of colon cancer involve testing every 10 years after age 50 and every 5 years in those individuals who appear to have any signal for slightly higher risk (e.g., the presence of polyps on a prior screening colonoscopy). The “New” Prostate Cancer InfoLink is of the opinion that some similar form of risk management protocol could be relatively easily developed for prostate and breast cancers, and would be much less likely to lead to over-treatment while still ensuring a high probability of early detection of clinically significant cancers.

8 Responses

  1. Just to recap, the US Preventive Services Task Force (USPSTF) recommends against PSA-based screening for prostate cancer for all men in the general US population, regardless of age. This was changed in 2012.

    I agree that there are many similarities between breast cancer and prostate cancer as it relates to the risks and benefits of screening.

    Given this study and numerous other ones concerning breast cancer screening, do you think that the USPSTF will change their recommendation for breast cancer to start mammogram screening at age 60? Or will they stay consistent and “recommend against mammogram-based screening for breast cancer for all women in the general US population, regardless of age”?

  2. Just a commentary …

    The patient community generally will not buy into studies showing a real issue with early detection schemas in prostate cancer. I underestimated how passionate that community is about screening everyone and screening them early and often. Which would of course exacerbate the findings of this study in a negative way and just about all prostate cancer screening studies I’ve read in the past 4 years. But that stated, there will always be a passionate screening camp up against a scientific screening camp up against a no screening USPSTF in prostate cancer screening. And as long as there is, there will be a divide in the discussions.

    But the research must continue. And this research raises some very real questions that need to be answered.

    In the end the patients will have understand that better data or better screening methods are needed. And the professionals and many advocates will have to remain on their toes with any news that goes against population-based screening in prostate cancer to be able to ward off a firestorm of accusation and even innuendo.

    Sigh.

  3. Jerry:

    I think that the USPSTF would like to recommend against all “screening” for breast cancer (by which I mean mass, population-based, annual testing using mammography). This does not mean that they would want to stop all testing. They would probably argue that such testing needs to be risk-based in some way still to be well defined.

    Unfortunately, as a a society, we are not rational about this issue (see this editorial in today’s NEJM), and it is highly political, so whether the USPSTF actually can and will is a whole different question. As of now, their most recent guidance remains in place, but you should remember that this guidance is not what they wanted to put in place at all.

  4. According to this article, the study on breast cancer screening is badly flawed.

    “Mammography is an imperfect test at best, but at this point, it’s the best test we have,” said Dr. Ann Partridge, a breast oncologist at Dana-Farber Cancer Institute. She and others highlighted some potential methodological flaws of the Canadian study.

    For example, Partridge said, technology has improved significantly over the past 30 years with X-ray machines and digitized film that yield clearer images.

    Others have questioned whether the women in the Canadian study were properly randomized since a significantly higher number of women in the mammography group were diagnosed with advanced cancers during the first year or two of the study than those in the control group.

    “This might have been due to chance,” Wender said, “but if the randomization wasn’t done perfectly, some women at higher breast cancer risk might have been put into the mammography group and this might have skewed the results.”

    Some radiologists have sharply attacked the study investigators, accusing them of having a bias against mammography by designing a study in which the control group of women in their 50s received breast exams performed by skilled nurses every year instead of mammograms.

    “The principal investigator set out to prove that all you needed to do was a physical examination,” said Dr. Daniel Kopans, director of breast imaging at Massachusetts General Hospital, in an e-mail responding to the new study finding. “The nurse examiners were highly trained while the radiologists and technologists [who performed the mammograms] had no training.”

    Baines, who has frequently sparred with Kopans through the years, said radiology leaders have remained “really committed” to advocating for mammograms partly for financial reasons, including insurance reimbursements and consultant fees they’ve received from mammography machine manufacturers.

  5. As mentioned above, this is a highly political (not to mention emotional) topic, just like PSA screening. It is utterly unsurprising that some people are going to react in the manner quoted in the article in The Boston Globe.

  6. “For example, Partridge said, technology has improved significantly over the past 30 years with X-ray machines and digitized film that yield clearer images.”

    Neglecting the fact that the 30-year-old technology is what was in place when the media blitz for screening started.

  7. I was diagnosed at age 44 with a PSA of 4. Biopsy (Gleason 9), surgery, etc., … confirmed Gleason 9, T3b, blah blah blah…. My journey started with a PSA test. For the last 4 years I have ranted and raved about screening for prostate cancer. I may be slowly changing my view on screening.

    My mother-in-law gets annual mammograms, with the latest imaging equipment available I might add. Her last mammogram prompted a biopsy which prompted surgery. (Nothing could be felt.) From her surgery, she was found to have lymph nodes involved. Stage 3 something.

    I asked how the mammogram was the year before and everything appeared to be good, I was told.

    I’m beginning to think, and this is tough for me, that there is a subset of men and women that despite any type of current screening will be faced with a cancer that would not have prevented an advanced stage.

  8. Jerry …. You might want to have a look at an OpEd in today’s New York Times entitled “Why I never got a mammogram

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