Thyroid Cancer Recurrence Definitions Still Lack Consensus

TOPLINE: 
There is no universally accepted definition for recurrence of differentiated thyroid cancer (DTC) across treatment categories such as total thyroidectomy with or without radioactive iodine ablation (RAI) and lobectomy. A newly published systematic review highlights the need for an international proposal to establish a standard definition.
METHODOLOGY:
The 10-year survival rate in DTC is more than 95%, making recurrence a critical outcome for evaluating treatment efficacy; however, international guidelines don’t provide a consistent definition of recurrence and instead offer different definitions based on various clinical, biochemical, and radiological criteria.
This systematic review aimed to delineate the definitions of DTC recurrence, categorized by total thyroidectomy with RAI, total thyroidectomy without RAI, and lobectomy.
The researchers conducted a systematic literature search in MEDLINE and EMBASE in March 2023 and analyzed 70 studies (69 retrospective studies and one randomized controlled trial) published between January 2018 and December 2023; the median number of patients in the included studies was 438.
Inclusion criteria encompassed studies on DTC evaluating recurrence after initial treatment, involving adult patients, children, or a mixed population.
The primary outcome was the definition of DTC recurrence, and the secondary outcome was whether studies differentiated between recurrence and persistent disease.
TAKEAWAY:
In the included studies, recurrence was identified by either cytology or histopathology, imaging techniques, serum thyroglobulin levels, tumor-free time span, or a combination of these diagnostic modalities.
Overall, 24.3% of studies reported on patients treated with lobectomy, with the most prevalent definition of recurrence following lobectomy being cytology- or pathology-proven recurrence (47.1% of this subgroup).
Thyroidectomy with and without RAI were reported by 70% and 5.7% of the studies, respectively. The most common definition of recurrence after total thyroidectomy with RAI was cytology/pathology-proven recurrence and/or anomalies observed on imaging (22.4% of this subgroup); however, no consistent definition was found after total thyroidectomy without RAI.
Only 12.9% of studies differentiated between recurrence and persistent disease, with total thyroidectomy with RAI being the only treatment category in these studies.
IN PRACTICE:
“The results of this systematic review give an overview of the extensive variation in the definitions of DTC recurrence and provide insight into the components that make up these definitions. Offering insight into these components can serve as an initial step toward establishing a globally standardized definition of DTC, which could facilitate comparisons of treatment regimens, prognoses, and other research,” the authors wrote.
SOURCE:
The study was led by Daniél J. van de Berg, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands. It was published online in Thyroid.
LIMITATIONS:
The study’s limitations included the heterogeneity of the definitions of recurrence, which may have affected the interpretation of the outcomes. There is a possibility of subjective bias as the process of selecting these studies may have been subject to some interpretation by the researchers. The exclusion of non-English studies may have limited the generalizability of the findings.
DISCLOSURES:
This work was supported by grants from Stichting Kinderen Kankervrij. The authors declared no conflicts of interest.
This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.
 
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