Active surveillance in low risk papillary thyroid carcinoma

Abstract

In recent decades, while the incidence of thyroid cancer has increased exponentially around the world, mortality has remained stable. The vast majority of this increase is attributable to the identification of intrathyroidal papillary microcarcinomas, which exhibit slow growth rates with indolent courses. A diagnosis of thyroid cancer based upon the presence of these small tumors could be considered as an overdiagnosis, as the majority of these tumors would not likely result in death if left untreated. Although surgical resection was the classical standard therapy for papillary microcarcinomas, active surveillance (AS) has emerged over the last three decades as an alternative approach that is aimed to recognize a minority group of patients who will clinically progress and would likely benefit from rescue surgery. Despite the encouraging results of AS, its implementation in clinical practice is strongly influenced by psychosocial factors. The aim of this review is to describe the epidemiology, clinical evolution, prognostic factors, and mortality of papillary thyroid microcarcinomas. We also summarize the AS strategy according to published evidence, characterize the criteria for selecting patients for AS according to risk factors and environmental characteristics, as well as analyze the current limitations for AS implementation.

Keywords: Active surveillance; Low risk; Papillary thyroid carcinoma; Observation; Papillary thyroid microcarcinoma; Thyroid cancer

Core tip: While the diagnosis of intrathyroidal papillary microcarcinomas has increased exponentially, the mortality rate has remained stable. Although surgical resection was the classic standard therapy, active surveillance has emerged as an alternative approach aimed to recognize a minority of patients who will clinically progress and would likely benefit from rescue surgery. During follow-up, these tumors (including those between 1-2 cm) evolve with no changes in size, have very slow growth rates, and even decrease in diameter. Given the high prevalence of papillary microcarcinomas and the excellent observational outcomes, active surveillance constitutes a safe and feasible alternative for properly selected patients.