Ethical issues raised by thyroid cancer overdiagnosis: A matter for public health?

Drivers of Thyroid Ultrasound Use: A Retrospective Observational Study

OBJECTIVE

Excessive use of thyroid ultrasound (TUS) contributes to the overdiagnosis of thyroid nodules and thyroid cancer. In this study, we evaluated drivers of and clinical trajectories following TUS orders.

METHODS

We conducted a retrospective review of 500 adult patients who underwent an initial TUS between 2015 and 2017 at Mayo Clinic in Rochester, MN. A framework was employed to classify the indication for TUS, and it was characterized as inappropriate when ordered without a guideline-based indication. Medical records were reviewed for up to 12 months following the TUS, and clinical outcomes were evaluated.

RESULTS

The mean age mean age (SD) was 53.6 years (16.6), 63.8% female, and 86.6% white. TUS orders were triggered by incidental findings on unrelated imaging (31.6%), thyroid symptoms (20.4%), thyroid abnormalities on routine physical examination (17.2%), and thyroid dysfunction workup (11.8%). In females and males, the most common reason were incidental findings on imaging (female, 91/319, 28.5% and male, 67/181, 37.0%). In primary care practice, TUS orders were mostly triggered by symptoms (71/218, 32.5%), while thyroid dysfunction workup was the primary reason in endocrinology (28/100, 28.0%). We classified 11.2% (56/500) TUS orders as likely to have been ordered inappropriately based on current guidelines. Finally, 119 patients (119/500, 23.8%) had a thyroid biopsy with 11.8% had thyroid cancer (14/119. 11.8%).

CONCLUSIONS

Incidental findings on imaging, symptoms, and routine physical exam findings in asymptomatic patients were the most prevalent drivers of TUS. Furthermore, 1 in 10 TUS were likely inappropriately ordered based on current practice guidelines.

The Economic Cost of Thyroid Cancer in France and the Corresponding Share Associated With Treatment of Overdiagnosed Cases

OBJECTIVES

Thyroid cancer incidence in France has increased rapidly in recent decades. Most of this increase has been attributed to overdiagnosis, the major consequence of which is overtreatment. We aimed to estimate the cost of thyroid cancer management in France and the corresponding cost proportion attributable to the treatment of overdiagnosed cases.

METHODS

Multiple data sources were integrated: the mean cost per patient with thyroid cancer was estimated by using the Echantillon Généraliste des Bénéficiaires data set; thyroid cancer cases attributable to overdiagnosis were estimated for 21 departments using data from the French network of cancer registries and extrapolated to the whole country; medical records from 6 departments were used to refine the diagnosis and care pathway.

RESULTS

Between 2011 and 2015, 33 911 women and 10 846 men in France were estimated to be diagnosed of thyroid cancer, with mean cost per capita of €6248. Among those treated, 8114 to 14 925 women and 1465 to 3626 men were due to overdiagnosis. The total cost of thyroid cancer patient management was €203.5 million (€154.3 million for women and €49.3 million for men), of which between €59.9 million (or 29.4% of the total cost, lower bound) and €115.9 million (or 56.9% of the total cost, upper bound) attributable to treatment of overdiagnosed cases.

CONCLUSIONS

The management of thyroid cancer represents not only a relevant clinical and public health problem in France but also a potentially important economic burden. Overdiagnosis and corresponding associated treatments play an important role on the total costs of thyroid cancer management.

Is conservative management of the indeterminate thyroid nodule [Thy3f or Bethesda category IV] safe?

PURPOSE

The histological diagnosis after diagnostic thyroidectomy for indeterminate thyroid nodules is often non-malignant and some cancers detected are considered 'indolent'. The safety and effectiveness of conservative management in these patients are unclear. The aim of this study was to determine the safety of conservative management of indeterminate thyroid nodules and to explore association between clinical features and pathology in patients undergoing surgery.

METHODS

This is a retrospective cohort study of patients presenting to a single centre over a 4-year period (2013-2016) with thyroid nodules that were considered indeterminate (thy3f in the UK RCPath classification) on cytology. Demographic data, ultrasound features, follow-up details (in those undergoing conservative management) and histology details (in those undergoing surgery) were collected.

RESULTS

Of 164 patients that had Thy3f cytology, 34 were initially managed conservatively; however, 4 of these eventually had surgery (due to patient preference). No patient on conservative management had significant disease progression on ultrasound at a median (interquartile range) of 27 (16-40) months. Of the 134 patients that underwent surgery, 26 had thyroid malignancy. The BTA 'U' classification, gender and age (> 55) were not associated with malignancy in these nodules, but larger nodules (> 40 mm) were more likely to be malignant (p = 0.042).

CONCLUSIONS

Conservative management of indeterminate (Thy3f or Bethesda stage IV) thyroid nodules is safe in the short term and may be indicated in selected cases after appropriate discussion of risks and benefits of surgery.

Young people's perspectives of thyroid cancer screening and its harms after the nuclear accident in Fukushima Prefecture: a questionnaire survey indicating opt-out screening strategy of the thyroid examination as an ethical issue

BACKGROUND

Overdiagnosis of thyroid cancer has become a major global medical issue. Ultrasound-based thyroid cancer screening has promoted overdiagnosis, and recently international recommendations state that it should not be conducted, even after a nuclear accident. The Fukushima thyroid cancer screening program was initiated in 2011 as a health policy after the nuclear accident. The risk of radiation-induced thyroid cancer was unlikely given the low radiation levels, but the thyroid cancer screening program has continued at 2-year intervals with a relatively high participation rate and is now in its fifth round. It is therefore crucial to clarify whether those targeted for screening understand the disadvantages of screening, and to identify factors that influenced their decision to participate.

METHODS

We conducted an anonymous mail-based questionnaire among young people from Fukushima Prefecture (subjects) and a neighboring prefecture that was not targeted for screening (non-subjects). We asked them about the significance of the thyroid cancer screening in Fukushima Prefecture, their reasons for accepting or refusing screening, their perception of the harms of screening, and their opinions on thyroid examination at school. We compared the results of the questionnaire between subjects and non-subjects and between examinees (who were screened) and non-examinees (who declined screening).

RESULTS

Only 16.5% of respondents were aware of the harms associated with thyroid cancer screening, with most perceiving that the benefits outweighed the harms. Comparison of subjects' and non-subjects' responses showed there were no significant differences between the two groups. Among subjects, there were also no differences in responses between examinees and non-examinees. The most common reason for participation in screening was that the screening was conducted in schools and perceived as obligatory.

CONCLUSIONS

These results highlighted a serious ethical issue in that school-based screening leads to making young people think that it is mandatory screening in an opt-out and default setting manner, with a lack of knowledge about the disadvantages of screening. Based on the autonomy of the subjects and the ethical principle of the post-disaster, surveys after a nuclear disaster should be conducted in an opt-in style without an opt-out style such as school-based screening.

Trends in the incidence of thyroid cancer in Incheon Province, South Korea, from 2004 to 2013: A representative sample study from Incheon cancer registry

AIM

This study aimed to assess the trends in the incidence of thyroid cancer in Incheon Province, South Korea, from 2004 to 2013 and to identify its association with thyroid cancer screening.

METHODS

We evaluated randomly sampled data of 10% of thyroid cancer patients collected between 2004 and 2013 from the Incheon Cancer Registry, Incheon, South Korea. The expected annual incidence rates of thyroid cancer from 2004 to 2013 were calculated, and the trends in annual incidence change were assessed using a Poisson regression model. In addition, the annual proportion change in the thyroid cancer population according to the detection method and tumor size was also calculated by evaluating the linear-by-linear association.

RESULTS

The average expected prevalence of thyroid cancer was 30 per 100,000 individuals from 2004 to 2013. The expected annual incidence of thyroid cancer per 100,000 individuals increased from 7 in 2004 to 49 in 2013, with an annual 1.25-fold difference (p < 0.001). Screening helped improve the detection of thyroid cancer annually, with the proportion increasing by screening detection (p < 0.001). Majority (54%) of the tumors were small (< 10 mm) and their detection rate increased from 2004 to 2013 (p < 0.001).

CONCLUSIONS

The incidence of thyroid cancer has increased from 2004 to 2013 in Incheon Province, South Korea, with the increase being most significant for small tumors. These findings indicate that the increased incidence is primarily due to the widespread use of screening and not an actual increase in clinically significant thyroid cancer.

Post-9/11 excess risk of thyroid cancer: Surveillance or exposure?

An excess risk of thyroid cancer has been reported in different World Trade Center (WTC)-dust exposed cohorts. Increased surveillance of these cohorts has been suggested as a potential explanation of this reported excess thyroid cancer risk leading to an increased diagnosis of earlier-stage thyroid cancers. However, the uncertainty to what extent surveillance or physician bias may be contributing to the reported incidence of thyroid cancer in WTC-dust exposed populations remains, highlighting the need to investigate a potential causal link between WTC dust exposure and thyroid cancer. Future studies are therefore indicated to investigate potential consequences of WTC dust exposure on the thyroid gland. Studies of the heavily exposed populations offer the possibility to better understand the mechanisms behind the exposure to a variety of environmental contaminants, and may provide useful insights into exposures harmful to the thyroid. These can be used in risk stratification when implementing screening in high-risk populations and may inform shared decision-making regarding the extent of thyroid cancer treatment.

Thyroid nodules 1 cm or less are related to Bethesda System nondiagnostic and suspicious for malignancy categories

OBJECTIVE

To compare the frequency of fine needle aspiration (FNA) cytological results between nodules 1 cm or less and nodules greater than 1 cm.

METHODS

All FNAs performed between January 2016 and December 2019 at an institute in Brazil were analysed. For each nodule, at least two conventional slides were produced (one stained by Giemsa and the other by hematoxylin and eosin). All cases were reviewed by two cytopathologists and were reported following the Bethesda System. Clinical information (gender and age) and ultrasound data (nodule size and location) were collected. The magnitude of association was measured using the prevalence ratio (PR) with 95% confidence intervals (CIs) considering two groups of nodules: 1.0 cm or less, and greater than 1 cm.

RESULTS

A total of 3703 nodules were analysed from 3265 patients (2906 women [88.48%], 359 men [11.51%], with a combined mean age of 52 years). Considering the prevalence ratio of Bethesda categories between these two groups of nodules, the nondiagnostic or unsatisfactory category (PR: 3.0, 95% CI: 2.2-4.2) and the suspicious for malignancy category (PR: 1.6, 95% CI: 1.1-2.4) were significantly associated with nodules measuring 1 cm or less.

CONCLUSION

Our results demonstrated that nodules 1 cm or less are significantly associated with the nondiagnostic and suspicious for malignancy categories of the Bethesda System when compared to nodules greater than 1 cm.

Overdiagnosis of Juvenile Thyroid Cancer

Overdiagnosis is the detection of a disease that does not do any harm to the patient throughout the lifetime. Thyroid cancer in children is a rare disease; however, since 2011, many children in Fukushima, Japan, have been diagnosed with it, and the number has shown a steady increase to over 200 cases at present. Some experts have stated that this phenomenon is due to overdiagnosis caused by thyroid ultrasound (US)-based thyroid screening detecting self-limiting thyroid cancer, which will not lead to clinical symptoms in the future. Harm caused by overdiagnosis of thyroid cancer is more serious in the young, since it is difficult to perform active surveillance and children diagnosed with cancer are likely to suffer from stigma. Thus, overdiagnosis of thyroid cancer in the young is not only a health problem but also a problem of human rights. Conflicts of interest among people related to screening programs and some experts with incomplete knowledge on overdiagnosis help to spread misleading opinions together with fear of radiation exposure among residents, which has led to their erroneous understanding of the nature of US-based thyroid screening. Scientific and honest discussions among experts to enhance education of residents and consideration of medical ethics are crucial to prevent the expansion of overdiagnosis.

Early Diagnosis of Low-Risk Papillary Thyroid Cancer Results Rather in Overtreatment Than a Better Survival

We are witnessing a rapid worldwide increase in the incidence of papillary thyroid carcinoma (PTC) in the last thirty years. Extensive implementation of cancer screening and wide availability of neck ultrasound or other imaging studies is the main reason responsible for this phenomenon. It resulted in a detection of a growing number of clinically asymptomatic PTCs, mainly low-risk tumors, without any beneficial impact on survival. An indolent nature of low-risk PTC, particularly papillary thyroid microcarcinoma (PTMC), and the excellent outcomes raise an ongoing discussion regarding the adequacy of treatment applied. The question of whether PTMC is overtreated or not is currently completed by another, whether PTMC requires any treatment. Current ATA guidelines propose less extensive preoperative diagnostics and, if differentiated thyroid cancer is diagnosed, less aggressive surgical approach and limit indications for postoperative radioiodine therapy. However, in intrathyroidal PTMCs in the absence of lymph node or distant metastases, active surveillance may constitute alternative management with a low progression rate of 1%-5% and without any increase in the risk of poorer outcomes related to delayed surgery in patients, in whom it was necessary. This review summarizes the current knowledge and future perspectives of active surveillance in low-risk PTC.

Upregulation of microRNA-143-3p induces apoptosis and suppresses proliferation, invasion, and migration of papillary thyroid carcinoma cells by targeting MSI2

As a tumor-associated biological molecule, microRNA-143-3p (miR-143-3p) is implicated in the progression of papillary thyroid carcinoma (PTC). We conducted this study to elucidate the effects of miR-143-3p mediated by Musashi RNA binding protein 2 (MSI2) on the biological activities of PTC cells. The K1 cells with the lowest miR-143-3p expression were selected for the experiments. The targeting relationship between miR-143-3p and MSI2 was verified. The biological functions of miR-143-3p and MSI2 with respect to K1 cell proliferation, cycle distribution, apoptosis, invasion, migration, and tumorigenesis were studied using gain- and loss-of-function assays both in vitro and in vivo. MSI2 was verified to be a target gene of miR-143-3p. Cells treated with upregulation of miR-143-3p or silencing of MSI2 exhibited significantly decreased the expression of Bcl-2, PCNA, MCM2, Ki67, MSI2, MMP-2, and MMP-9. This was accompanied by inhibited cell proliferation, cell invasion, and migration, as well as a significant increase in Bax expression, cell cycle arrest, and cell apoptosis. More importantly, the tumor inhibitory effects of upregulated miR-143-3p were also confirmed in the tumor xenografts in nude mice. Our results indicate that upregulation of miR-143-3p suppresses the progression of PTC by impeding cell growth, invasion, and migration via downregulation of MSI2, highlighting the potential of miR-143-3p as a target for future PTC treatment.

Analysing the ethics of breast cancer overdiagnosis: a pathogenic vulnerability

Breast cancer screening aims to help women by early identification and treatment of cancers that might otherwise be life-threatening. However, breast cancer screening also leads to the detection of some cancers that, if left undetected and untreated, would not have damaged the health of the women concerned. At the time of diagnosis, harmless cancers cannot be identified as non-threatening, therefore women are offered invasive breast cancer treatment. This phenomenon of identifying (and treating) non-harmful cancers is called overdiagnosis. Overdiagnosis is morally problematic as it leads to overall patient harm rather than benefit. Further, breast cancer screening is offered in a context that exaggerates cancer risk and screening benefit, minimises risk of harm and impedes informed choice. These factors combine to create pathogenic vulnerability. That is, breast cancer screening exacerbates rather than reduces women's vulnerability and undermines women's agency. This paper provides an original way of conceptualising agency-supporting responses to the harms of breast cancer overdiagnosis through application of the concept of pathogenic vulnerability.

Is an indistinct picture "exactly what we need"? Objectivity, accuracy, and harm in imaging for cancer

Assumptions about the epistemic ideal of objectivity, closely related to ontological assumptions about the nature of disease as pathophysiological abnormality, lead us into oversimplified ways of thinking about medical imaging. This is illustrated by current controversies in the early detection of cancer. Improvements in the technical quality of imaging failed to address the problem of overdiagnosis in breast cancer screening and exacerbate the problem in thyroid cancer diagnosis. Drawing on Douglas and on Daston and Galison, I distinguish 3 dimensions of objectivity (accuracy, reliability, and precision) and demonstrate ways they may be at odds, as illustrated in the early detection of cancer. Guidelines for evaluating the efficacy of diagnostic imaging are insufficiently sensitive to this complexity. Improving imaging quality may raise epistemic issues, place disease definitions in question, and lead to overall harm or to changes in the distribution of harms and benefits among population subgroups. With a nod to Wittgenstein, I argue that we cannot take for granted that "an indistinct picture" is not "exactly what we need."

Précising definitions as a way to combat overdiagnosis

Roughly, overdiagnosis (ODx) occurs when people are harmed by receiving diagnoses (often accompanied by interventions) that do not benefit them, usually because the diagnosed conditions do not pose a threat to their health. ODx is a theoretical as well as a practical problem as it relates to definitions of disease. Elsewhere, it has been argued that disease is a vague concept and that this vagueness may contribute to ODx. In response, we develop a stipulative or précising definition of disease, for the specific purpose of decreasing or preventing ODx. We call this disease_ODx , aimed at distinguishing cases where it would be beneficial to identify (and treat the condition) from those where diagnosis is more likely to harm than benefit. A preliminary definition of disease_ODx is that X is a disease_ODx iff there is dysfunction that has a significant risk of causing severe harm. This paper examines the 3 concepts in this definition, using a naturalistic account of function, a Feinbergian account of comparative harm, and a probabilistic understanding of risk. We then test the utility of this approach using examples of clinical conditions that are currently overdiagnosed.

Long term outcomes of simple clinical risk stratification in management of differentiated thyroid cancer

OBJECTIVE

To establish the long term outcomes of risk stratified management of differentiated thyroid cancer (DTC).

BACKGROUND

Guidelines for management of DTC lack a strong evidence base and expose patients to overtreatment. This prospective study of patients diagnosed with DTC between 1977 and 2012 describes the long term outcomes of a conservative risk stratified (AMES) management policy.

METHODS

Outcomes were analysed around patient and tumour characteristics, primary intervention (surgery ± radioiodine (RAI)), in terms of mortality, recurrence and reintervention.

RESULTS

Median follow-up in 348 patients was 14 years: mean age 48 (range 10-91) years, 257 (73.9%) female, 222 (68.3%) papillary cancer, tumour size 3.4 ± 2.0 cm (mean ± SD). 89 (25.6%) AMES high risk, 116 (33.3%) TNM stage III/IV and 16 (4.6%) had distant metastases. Primary surgery comprised lobectomy in 189 (54.3%): 11 (5.8%) patients had subsequent completion total thyroidectomy with cancer present in five. Primary nodal surgery was performed in 142 (40.8%) patients. 35 (13.5%) low and 43 (48.3%) high risk patients received RAI following initial surgery. Overall disease specific survival (DSS) was 92.1% at 10 years and 90.7% at 20 years. DSS at 20 years was 99.2% in low risk cases. AMES risk scoring predicted both survival and recurrence. Patients receiving RAI and AMES high risk were significantly associated with increased risk of death and recurrence.

CONCLUSIONS

Routine total thyroidectomy and RAI are not justifiable for low risk DTC. Treatment should be tailored to risk and AMES risk stratification remains a simple reliable clinical tool.