Recently, the New England Journal of Medicine (NEJM) published an article about the overdiagnosis of thyroid cancer. The study, which was written by epidemiologists from the World Health Organization found striking evidence for the overdiagnosis of thyroid cancer in many developed countries around the world. According to the article, and in agreement with many past studies, the introduction of various diagnostic imaging techniques in recent decades has resulted in a “massive” increase in the detection of papillary thyroid cancers, especially smaller cancers. Besides revealing a reservoir of thyroid nodules (most studies estimate that about 5% are cancers) in the population that had previously gone undetected; the technology itself has also made “opportunistic” screening for disease possible. This means that doctors can screen for disease in asymptomatic patients. Such a program was implemented formally in South Korea, which has been “rewarded” with the highest incidence of thyroid cancer in the world, but without a decrease in mortality rates.
The publication of the NEJM study was covered in the popular press and also by National News outlets such as NBC. In an unprecedented move, The American Thyroid Association (ATA), published a statement on the overdiagnosis of thyroid cancer which called for fewer biopsies of small thyroid nodules under 1 cm in size as well as “active surveillance” or lobectomy (removal of half the thyroid gland) for some patients with thyroid cancer. These measures are recommended in hopes of uncovering fewer small, asymptomatic thyroid cancers and also in order to reduce over treatment for patients with thyroid cancer.
The chief patient support and advocacy group in the United States for thyroid cancer is THYCA Inc, the Thyroid Cancer Survivors’ Association. THYCA sponsors many visible events and publications about thyroid cancer, including a yearly conference that is well attended by both patients and physicians. They also award medical research grants for the different types of thyroid cancer ( Some thyroid cancers are life threatening, although the majority are treatable or apparently may require no treatment). In response to the publicity garnered by the NEJM article, THYCA released a statement which referred to “overdiagnosis” as an erroneous characterization:
The point of these articles should be about the question of treatment, and potentially over-treatment. It is erroneous to classify the situation as one of overdiagnosis, and, more importantly, it is inappropriate to downplay the diagnosis of cancer to the public and those in the health care field. Knowledge is power, and even people with smaller cancers deserve to know what is going on with their bodies. – Gary Bloom, executive director of THYCA
Bloom’s statement appears to be based on a definition of cancer that is increasingly viewed as being anachronistic. As previously mentioned on this blog, a 2013 editorial by Esserman et al and published in the Journal of the American Medical Association called for the re-naming of some cancers as IDLE (Indolent Lesion of Epithelial Origin), in order to recognize the heterogeneous nature of tumors which are currently labeled as being cancers. This influential piece has been cited 282 times at this writing. The newer data which has engendered the literature on overdiagnosis are found in studies which indicated that cancer screening (early detection) has uncovered many indolent lesions which were not destined to progress and kill their hosts. Esserman et al write:
Physicians, patients,and the general public must recognize that overdiagnosis
is common and occurs more frequently with cancer screening. Overdiagnosis, or identification of indolent cancer, is common in breast, lung, prostate, and thyroid cancer. Whenever screening is used, the fraction of tumors in this category increases. By acknowledging this consequence of screening, approaches that mitigate the problem can be tested.
Although formal screening for thyroid cancer by ultrasound is not currently practiced in the United States as it has been in South Korea, there is little doubt that the use of ultrasound and other imaging techniques have caused most of the increase in the incidence of thyroid cancer. The recent statement by the ATA which gave credence to the concept of overdiagnosis as it pertains to thyroid cancer is probably tied to the selection of John C. Morris of the Mayo Clinic as its president-elect. Morris has co-authored influential articles about imaging and thyroid cancer; among them is the one cited above. Given the acceptance of the role of imaging and the high likelihood that the discovery of indolent lesions labeled as “cancer” is harming a very significant portion of papillary thyroid cancer patients, it is difficult to see how THYCA’s recent statement is going to help the growing community of thyroid cancer “survivors” both in the United States and in other parts of the developed world to be informed about the condition, and the likelihood of over treatment.
The concept of “overdiagnosis” as it pertains to thyroid cancer seems to have been first brought forward in the medical literature by Davies and Welch in 2006. Since that time, and because of the increasing incidence of the disease, the concept has gained increasing credence in academia for thyroid cancers (mostly papillary) as well as other cancer types. There have also been several studies published finding that “overdiagnosis” is not well understood by laypeople who have been inculcated by public campaigns which stress the early detection of cancer as being lifesaving. Most cancer survivors’ organizations, such as THYCA, have relied upon the slogan “early detection saves lives” as part of their awareness efforts directed at the public. While THYCA has not promoted the use of ultrasound screening per se as a tool for detection of thyroid cancer, they do promote “neck checks” and urge the public to “catch it early”. The task of backtracking or qualifying the promotion of “early detection” as a life-saver may be a formidable one for an organization which has included it as part and parcel of its public outreach. Any such attempt at clarification would have to include a public education effort aimed at explaining counter-intuitive concepts that can be somewhat difficult to grasp.
A recent article published in the Journal of Evaluation in Clinical Practice, written by Rogers and Mintzger, made recommendations for dealing with overdiagnosis caused by “maldetection”. Maldetection occurs when “the diagnosis is based on an accepted gold standard test for particular diseases, but the presence of a positive result cannot tell us which individual patients have harmful disease and which patients have non-harmful disease.” The authors cite papillary thyroid cancer as being a prime example of overdiagnosis occurring as the result of maldetection. They further opine:
Where there are high rates of maldetection (typified by rapid increases in diagnoses with no associated decreases in mortality), this may be a prima facie reason to: identify relevant drivers and curtail these to the extent possible; rethink the original disease category; or specify intervention thresholds that are distinct from diagnosis (as has occurred with recommendations regarding micro-papillary thyroid cancer).
The recent ATA statement on overdiagnosis coupled with their 2015 Guidelines for thyroid nodules and thyroid cancer appear to acknowledge that there is likely “maldetection” occurring within the medical specialties which address the problems of thyroid nodules and thyroid cancer. While an official reclassification of some indolent papillary carcinomas may still be years away, a model has recently been established by the new NIFTP designation for non-invasive encapsulated follicular variant. The recommendations in the guidelines which limit biopsies for nodules under 1 cm and sanction active surveillance for some small lesions, will likely have an effect of lessening or leveling the incidence of papillary thyroid cancer. These actions by the ATA can be interpreted by any reasonable person as an acknowledgement of a situation consistent with”overdiagnosis”.
Public misconceptions and misunderstandings about cancer overdiagnosis would therefore seem to be a logical target for the development of educational materials and outreach efforts by patient advocacy organizations such as THYCA. Interestingly, a surrogate of the THANC Foundation (Thyroid, Head and Neck Cancer Foundation) entered the ethics arena by being a co-author of a recent article published in Thyroid about the ethical ramifications of the NIFTP reclassification. The authors of this article recommend that with respect to the reclassification, ” the prudent course would be to attend to the requirements of medical ethics.” In contrast, THYCA has thus far remained silent on the many ethical issues related to NIFTP, other than stating that past cases of NIFTP were treated according to the standards of the time. However, it could and has been argued that medical professionals and others in a position to interact with patients have an obligation to inform them about ethical issues such as overdiagnosis as they pertain to certain kinds of thyroid cancer.
Rather than ethics per se, the reasons for THYCA’s objection to the use of the word “overdiagnosis” in describing current trends related to papillary thyroid cancer, appear to be related to protecting the feelings of patients with whom THYCA has interacted as a source of information and support. Gary Bloom’s statement refers to the recent media articles as triggering ” unnecessary upset among people who are currently being treated or have been treated in the past for thyroid cancer.” While it’s almost certainly true that the reports have caused “upset”, Bloom’s assertion can be construed as a willingness to shortchange the informational needs of future patients in favor of shielding the current membership. This arguably opens up all sorts of issues about the responsibility of survivors’ organizations to truthfully meet medical informational needs as well as to offer emotional support. Furthermore, if the American Thyroid Association has recently acknowledged the ethical dimensions of overdiagnosis by acting on behalf of its curtailment, it begs the question of what organizations such as THYCA would gain by denying its existence and thus foregoing an opportunity to educate its membership.
Keep reading here for more articles on this topic.