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Commentary |
1 Department of Radiology, Weill Medical College of Cornell University, The New York Presbyterian Hospital, New York, NY 10021.
Address correspondence to D. F. Yankelevitz
(dyankele{at}med.cornell.edu).
Keywords: cancer • screening • social responsibility
The February 2007 AJR health policy commentary, "CT Screening for Lung Cancer: Implications on Social Responsibility" by Lee and Forman [1], was motivated by our recent publication in the New England Journal of Medicine [2] on the results of the International Early Lung Cancer Action Program (I-ELCAP). The authors acknowledge the promise of the results, but also express reasons to be cautious. They caution that our study has not addressed various screening biases, workup of benign findings, radiation risks, costs, etc. Against this backdrop, they address whether, and under what conditions, to recommend screening. They conclude that informed consent is the most reasonable basis for the screening, which generally accords with the current recommendations from the American Cancer Society.
Lee and Forman [1] assert that randomized controlled trials contrasting screening with no screening will determine whether CT screening for lung cancer will be beneficial. This view has also been expressed by others, and great emphasis is thus being placed on the results that will come from the National Lung Screening Trial (NLST).
When potential saving of countless lives is at issue, social responsibility extends beyond the scientific community, most notably to include the government. This is especially the case when the evidence leads to conflicting interpretations by the scientists concerned, and ultimately to confusion among physicians and, of course, the people they advise.
This occurred with breast cancer screening. In the October 20, 2001, issue of the Lancet, a research letter titled "Cochrane Review on Screening for Breast Cancer with Mammography" was published [3]. The review included seven completed randomized controlled trials involving over a half million women, and the authors concluded that: "In 2000, we reported that there is no reliable evidence that screening for breast cancer reduces mortality. As we discuss here, a Cochrane review has now confirmed and strengthened our previous findings" [3].
This view was supported by an associated commentary written by the editor of the Lancet and subsequently also by the screening-and-prevention editorial board of the Physician Data Query (PDQ), an expert advisory panel to the U.S. National Cancer Institute. Valerie Jackson, in her article, "Screening Mammography: Controversies and Headlines" [4], which was honored at the Radiological Society of North America 2002 meeting by being presented as the "Annual Oration in Diagnostic Radiology," described how the controversy and the deep concern about a potential change in public policy were being presented in the lay press.
"The most damaging of these were published in the New York Times. Headlines such as `Analysis: Mammograms Don't Cut Cancer Death Rate,' `Breast X-Ray Doubts Raised,' `Are Mammograms Worth It?,' `Why Place Women's Health in the Hands of Self-Interested Professionals?,' and `Circling the Mammography Wagons' were seen on the front pages of newspapers and magazines almost daily in January and February of 2002" [4].
As a result of the confusion generated by these reports, on February 28, 2002, a congressional hearing was held to examine the conflicting findings regarding mammography usage and update recommendation guidelines, based on the most current scientific data, on the use of mammography in breast cancer detection [5]. In the hearings, the expert statisticians representing various task forces continued to disagree about the interpretation of the results of the randomized controlled trials regarding the benefit of mammography. By contrast, the clinicians, the director of the National Cancer Institute, the chief medical officer for the American Cancer Society, and medical experts representing several other major organizations concerned with screening for breast cancer, each in their own way stated the obvious: "Treatment is easier and the outcomes are better, when the cancer is caught before there is lymph node involvement and before the cancer has metastasized, or spread, to distant organs. There is no more consistent and straightforward measure of a breast cancer patient's prognosis than the size of the tumor" [5].
The desirability of early diagnosis on account of the greater effectiveness of early treatment was consistently brought up as the reason to continue to recommend mammography: This type of thinking was described in the hearings as "the logic behind early detection" [5].
Regarding potential harms from screening, such as those from "false positive" findings or overdiagnosis, the testimonies were not based on evidence from randomized controlled trials. With regard to "false positives," it was noted that diagnostic algorithms will continue to improve and that people understand the inevitability of some "false"—true but benign—positives. As for overdiagnosis, it was recognized that the issue was that of overtreatment, and that the need was to suitably tailor the treatments for less aggressive cancers.
In concluding the hearing, the chair noted "First of all, what we see is that the biostatisticians disagree. That is clear. And they will continue to look at data and analyze it. Clinicians, those who have the lives of patients in their hands, do not disagree...and recommend in the most enthusiastic, unabashed, and unqualified way that we follow the existing guidelines..." [5].
That hearing exemplifies the government exercising its social responsibility to sort out complex medical issues. In this case, the logic of the clinicians, those who directly dealt with women concerned about their risk for breast cancer, was persuasive.
A point that came up in that hearing and has particular relevance today in the context of lung cancer screening, was the explanation of why the mammography randomized controlled trials failed to show the benefit. A research letter published in the Lancet, written by some of the I-ELCAP investigators [6], was cited.
Jackson [4] described that publication as the turning point in the mammography controversy: "In early February 2002, the tide finally began to turn with the publication of an article by Miettinen et al. [6] in the February 9th issue of the Lancet."
The letter explained that two conditions need to be met in order for a screening randomized controlled trial to produce meaningful results: the screening is to continue long enough for the reduction in deaths to become fully manifest; and as the deaths averted as a result of the early treatment associated with screening are well into the future, it is necessary to focus the mortality comparison on an appropriate, suitably delayed time interval after the screening's initiation to document the full reduction in mortality. When these principles were applied by Miettinen et al. [6] to the data from the Malmö study, which was one of the breast cancer screening randomized controlled trials that had been taken to show no benefit, that study gave evidence of a dramatic benefit [6].
The confusion surrounding breast cancer screening a few years ago is recurring with respect to CT screening for lung cancer today. Many question whether any benefit is associated with it. Those design and analysis deficiencies described above for the mammography randomized controlled trials are present in the current lung screening trials, including the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial and the NLST. Both of those trials involve only a few rounds of screening and lack of focus on the relevant period of follow-up. Therefore, their results will likely be misleading as were those of the randomized controlled trials of mammography.
From the vantage of social responsibility, a critical question needs to be answered: Why don't many clinicians apply the obvious logic to deduce the beneficiality of lung cancer screening (as they did in the case with regard to mammography)? The logical reasons for performing lung cancer screening are even more compelling than they are for breast cancer. Lung cancer is even more fatal when diagnosed in a late stage, and is highly curable if diagnosed early.
Much promise has been placed on the results of the ongoing lung screening randomized controlled trials yet there is appropriate concern that the results of these trials are liable to be misleading, while the lay press is playing out a state of confusion. Social responsibility, of course, means more open discussion, but beyond that, isn't it time to include representatives of society extending beyond the scientific community and the media? Parallel to the experience with acceptance of breast cancer screening, perhaps it is time for congressional hearings.
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  J. G. Ravenel, P. Costello, and G. A. Silvestri Screening for Lung Cancer Am. J. Roentgenol., March 1, 2008; 190(3): 755 - 761. [Abstract] [Full Text] [PDF]
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