Evaluating Disease Specific Survival Prediction of Risk Stratification and TNM Systems in Differentiated Thyroid Cancer

BACKGROUND

Many countries have national guidelines for the management of differentiated thyroid cancer (DTC), including a risk stratification system to predict recurrence of disease. Studies whether these guidelines could also have relevance, beyond their original design, in predicting survival are lacking. Additionally, no studies evaluated these international guidelines in the same population, nor compared them to the TNM system. Therefore, we investigated the prognostic value of six stratification systems employed by ten International guidelines, and the TNM system with respect to predicting disease specific survival (DSS).

METHODS

We retrospectively studied adult patients with DTC from a Dutch university hospital. Patients were classified using the risk classification described in the British, Dutch, French, Italian, Polish, Spanish, European Society of Medical Oncology, European Thyroid Association, and 2009 and 2015 American Thyroid Association (ATA) guidelines, and the latest TNM system. DSS was analyzed using the Kaplan-Meier method, and the statistical model performance using the C-index, AIC, BIC and PVE.

RESULTS

We included 857 patients with DTC (79% PTC, 21% FTC). Median follow-up was 9 years, and 67 (7.8%) died due to DTC. The Dutch guideline had the worst statistical model performance, while the 2009 ATA/2014 British guideline had the best. However, the (adapted) TNM system outperformed all stratification systems.

CONCLUSIONS

In a European population of patients with DTC, out of ten International guidelines employing six risk of recurrence stratification systems and one mortality based stratification system, our optimized age-adjusted TNM system (8th edition) outperformed all other systems.

Appropriateness of ultrasound imaging for thyroid pathology, the standard of radiology reporting on thyroid nodules and the detection rates of thyroid malignancy: a tertiary centre retrospective audit

BACKGROUND

The incidence of thyroid cancer is increasing worldwide without a simultaneous rise in mortality. It is thought that the incidence of non-clinically significant thyroid cancers are on the rise as a result of more sensitive diagnostic imaging.

AIM

To determine the number of inappropriate requests for thyroid ultrasound (US), the quality of radiology reporting for thyroid nodules based on accepted guidelines and the resultant number of thyroid cancers identified because of these investigations.

METHODS

Electronic medical records of patients who underwent thyroid US imaging and thereafter referred to the Endocrine Department at Gold Coast University Hospital, Queensland, between July 2014 and July 2017 were reviewed. Data for 251 patients who had thyroid US were analysed and the final 201 patients who were found to have thyroid nodules were evaluated using descriptive statistics. Indications for thyroid US imaging among referring clinicians were assessed and we compared both clinical management and radiology reporting practices of thyroid nodules to the published 2009 and 2015 American Thyroid Association (ATA) guidelines.

RESULTS

There were 50.2% of patients with initial thyroid US imaging deemed outside of expert recommendations where 42% of these patients required further surveillance imaging and 25.4% required fine needle aspiration of their thyroid nodules. A definite recommendation whether to evaluate thyroid nodules further was provided in 44.8% of radiology reports. There were no radiology reports that described thyroid nodules findings based on patterns as recommended by the 2015 ATA guidelines. Two cases of thyroid cancer were detected including one patient with prior history of thyroid cancer and a second patient with hypothyroidism.

CONCLUSION

Routine use of US thyroid imaging outside expert recommendation is common. There is lack of standardised reporting when assessing thyroid nodules on US. Limiting the initial use of US in cases of palpable neck lumps and the use of systematic reporting according to the 2017 guidelines published by the American College of Radiology Thyroid Imaging Reporting and Data System may reduce unnecessary investigations for thyroid nodules in the future.

Disease Severity at Presentation in Patients with Disease-Related Mortality from Differentiated Thyroid Cancer: Implications for the 2015 ATA Guidelines

BACKGROUND

The current trend of less aggressive treatment of low-risk differentiated thyroid cancer (DTC) patients was recently challenged by a study reporting >10% disease-related mortality (DRM) in low-risk patients ablated with radioiodine activities below 54 mCi. However, this study and others were limited by incomplete data on disease severity at presentation. Whether patients presenting with low-risk disease are at risk for disease-related mortality is crucial for planning current treatment strategies.

METHODS

Patients with documented DRM from DTC were included from the Rabin thyroid cancer registry and the Davidoff Head and Neck cancer service databases. Disease characteristics at presentation, treatments, disease course, and cause of death were analyzed.

RESULTS

Of 1374 patients whose charts were reviewed, 56 were confirmed to have died of DTC, and 53 had sufficient data for analysis. Median time from diagnosis to death was 9 years (range 1-36). Cause of death was related to distant metastases in 46 patients and aggressive neck disease in 7 patients. The median age at diagnosis was 62 years (range 22-83, 83% older than 45), and were initially categorized as American Thyroid Association high risk in 89% of cases (in 4 cases due to high thyroglobulin levels), intermediate risk in 6% (3 older patients with N1b disease), misclassification as benign in one case, and none was low risk. Most patients had an advanced disease stage (stage IV, 88%; III, 2%; II, 2%; I, 8%). All patients with stage I disease were <45 years, with aggressive features (1 poorly differentiated, 3 gross extrathyroidal extension). One patient with stage II disease was <45 years and had distant metastases. Detection of distant metastases occurred within the first year in 25 patients and during subsequent follow-up in 25 patients. Overall, aside from one patient who was misdiagnosed as having a benign follicular adenoma at presentation, all patients had aggressive disease features at presentation.

CONCLUSION

None of the patients with DRM had low-risk features at presentation, supporting the current paradigm of less aggressive approach in the low-risk group. Studies analyzing mortality from thyroid cancer should stratify patients into the various risk categories based on full baseline data, including postoperative thyroglobulin levels.