RESUMO
Background Recurrence is a key outcome to evaluate treatment effect of differentiated thyroid carcinoma (DTC). However, no consistent definition of recurrence is available in current literature or international guidelines. Therefore, the primary aim of this systematic review was to delineate the definitions of recurrence of DTC, categorized by total thyroidectomy with radioactive iodine ablation (RAI), total thyroidectomy without RAI and lobectomy, to assess if there is a generally accepted definition among these categories. Methods This study adhered to 2020 PRISMA statement. In December 2023, systematic literature search in MEDLINE and EMBASE was performed for studies reporting on recurrence of DTC, from January 2018 to December 2023. Studies that did not provide a definition were excluded. Primary outcome was the definition of recurrence of DTC. Secondary outcome whether studies differentiated between recurrence and persistent disease. Two independent investigators screened titles and abstracts, followed by full-text assessment and data extraction. The study protocol was registered in PROSPERO,CRD42021291753. Results In total, 1450 studies were identified. Seventy studies met inclusion criteria, including 69 retrospective studies and one RCT. Median number of patients in included studies was 438 (range 25 - 2297). Seventeen studies (24.3%) reported on lobectomy, four studies (5.7%) on total thyroidectomy without RAI, and 49 studies (70.0%) with RAI. All studies defined recurrence using one or a combination of four diagnostic modalities: cytology/pathology, imaging studies, thyroglobulin(-antibodies), predetermined minimum tumor-free time span. The most common definition of recurrence following lobectomy was cytology/pathology-proven recurrence (47.1% of this subgroup), following total thyroidectomy with RAI was cytology/pathology-proven recurrence and/or anomalies detected on imaging studies (22.4% of this subgroup). No consistent definition was found following total thyroidectomy without RAI. Nine studies (12.9%) differentiated between recurrence and persistent disease. Conclusion Our main finding is that there is no universally accepted definition for recurrence of DTC in the current studies across any of the treatment categories. The findings of this study will provide the basis for a future, international Delphi-based proposal to establish a universally accepted definition of recurrence of DTC. A uniform definition could facilitate global discussion and enhance the assessment of treatment outcomes regarding recurrence of DTC.
RESUMO
BACKGROUND: The impact of multifocality and bilaterality on recurrence in patients with low-risk papillary thyroid cancer (PTC) is relevant when considering patients for a de-escalated treatment strategy: hemithyroidectomy instead of total thyroidectomy followed with or without radioactive iodine. This study aims to analyze contralateral tumor probability in patients treated for low-risk PTC and assess multifocality and bilaterality as possible predictors for recurrence. METHODS: Patients with low-risk PTC treated with total thyroidectomy followed with or without radioactive iodine in the Netherlands between 2005 and 2015 were included in this study. Patients were identified from the Netherlands Comprehensive Cancer Organization (IKNL) and linked with the nationwide network and registry of Pathology in the Netherlands (PALGA). Contralateral tumor probability and recurrence were assessed. RESULTS: Of 791 included patients, 41.8% (331 of 791) had multifocal disease, with 68.9% (228 of 331) of those patients having bilateral disease. The contralateral tumor probability after hemithyroidectomy was 24.6% (150 of 610) for patients with unifocal disease and 43.1% (78 of 181) for patients with multifocal disease. We found a higher trend of recurrence in patients with bilateral disease, regardless of multifocality: in patients with contralateral disease after precompletion diagnosed unifocal disease 7.3% (11 of 150) had recurrent disease, and patients without contralateral disease after precompletion diagnosed multifocal disease 1.9% (2 per 103) had recurrence. Cox regression analysis showed that bilaterality (hazard ratio = 3.621, 95% confidence interval = 1.548 to 8.471) was the sole statistically significant risk factor for recurrence. CONCLUSION: Low recurrence rates are found in patients with either multifocal or bilateral disease with low-risk PTC. Bilaterality should be taken into account when considering these patients for de-escalated treatment strategy.