Abstract
Active surveillance (AS) can be considered as an alternative to immediate surgery in low-risk papillary thyroid microcarcinoma (PTMC) without clinically apparent lymph nodes, gross extrathyroidal extension (ETE), and/or distant metastasis according to American Thyroid Association. However, in the past AS has been controversial, as evidence supporting AS in the management of PTMC was scarce. The most prominent of these controversies included, the limited accuracy and utility of ultrasound (US) in the detection of ETE, malignant lymph node involvement or the advent of novel lymph node malignancy during AS, and disease progression. We summarized publications and indicated: (1) US, performer-dependent, could not accurately diagnose gross ETE or malignant lymph node involvement in PTMC. However, the combination of computed tomography and US provided more accurate diagnostic performance, especially in terms of selection sensitivity. (2) Compared to immediate surgery patients, low-risk PTMC patients had a slightly higher rate of lymph node metastases (LNM), although the overall rate for both groups remained low. (3) Recent advances in the sensitivity and specificity of imaging and incorporation of diagnostic biomarkers have significantly improved confidence in the ability to differentiate indolent vs. aggressive PTMCs. Our paper reviewed current imagings and biomarkers with initial promise to help select AS candidates more safely and effectively. These challenges and prospects are important areas for future research to promote AS in PTMC.
Highlights
In an early era of medicine, cancer was diagnosed at advanced and incurable stages due to poor diagnostic technologies and limited therapeutic options
Choi et al demonstrated that contrast-enhanced computed tomography (CT) imaging correctly diagnosed a PTC patient as T4, while US alone would have categorized the patient as T3
Criteria category: A: focal bulging out or disruption of the thyroid capsule by tumor or more than 25% of perimeter of the tumor was abutting the thyroid capsule; B: vessels extending to or from the nodule were seen beyond the capsule on either color or power Doppler images; C: the absence of a clear adventitia, dilatation of the cartilage space or tumor extension into the space, or irregularity of the tracheal mucosa; D: loss of normal esophageal layer by tumor, the tumor was in contact with 180◦ or more of the circumference of the vessel and tumor invasion into the vessels lumen or a tumor occupying the tracheal esophageal groove; E: the loss of echo-genic perithyroidal fat tissue by tumor
Summary
In an early era of medicine, cancer was diagnosed at advanced and incurable stages due to poor diagnostic technologies and limited therapeutic options. The most comprehensive study of AS in papillary thyroid microcarcinoma (PTMC) was conducted by the Kuma hospital in Japan In their prospective trial, 8% of 1,235 PTMC patients demonstrated tumor enlargement ≥3 mm and 3.8% demonstrated novel lymph node metastases (LNM) at 10-year follow-up [15]. Patients and clinicians alike worry delaying immediate treatment, as would be indicated by AS, may result in more extensive surgical intervention should substantial disease progression occur from the time of initial diagnosis. To address these concerns, it is essential to critically evaluate the ability of diagnostic imaging and biomarkers to accurately stratify risk in PTMC patients
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