Active Surveillance of Low-Risk Papillary Microcarcinoma of the Thyroid in Indian Scenario: Are we Ready for it? A Narrative Review

Abstract

Papillary microcarcinoma (PMC) is defined as papillary thyroid carcinoma (PTC) measuring ≤1 cm, irrespective of the presence or absence of the high-risk features. PMCs without any high-risk features referred to as the low-risk PMCs are generally indolent, and most of them remain latent without progression or with very slow progression. Active surveillance (observation without immediate surgery) could identify the small minority of PMCs that progress and rescue surgery for these PMCs should be effective resulting in no influence on the patients' prognosis than performing immediate surgery which might result in more harm than good due to associated morbidity. So, with proper patient selection, organization, and patient counselling, active surveillance has the potential to be a long-term management strategy for patients with PMC. The recent update of the ATA guidelines (2015) incorporated active surveillance as an option within the management protocol of PTC, making it an considerable rather than an experimental treatment option. The cost for immediate surgery is higher than the medical costs of active surveillance for 10 years in most scenarios. Developing countries like India may have certain limitations like lack of understanding, financial constraints and lack of adequate radiology services; hence, we propose additional recommendations along with standard surveillance strategy.

Keywords: Active surveillance; India; low-risk papillary microcarcinoma of the thyroid; surgery in PMCs; surveillance in PMCs.

Figure 1

Baseline USG(a and b) showing the hypoechoic nodule in the left thyroid lobe with incomplete peripheral calcifications and minimal peripheral vascularity, proven to be papillary carcinoma on FNAC. The first and last follow‑up images(c and d respectively) showing stability of left lobe microcarcinoma. USG=Ultrasonography, FNAC=Fine‑needle aspiration cytology

Figure 2

Baseline USG(a and b) showing an ill‑defined solid markedly hypoechoic suspicious left thyroid lobe nodule which was hard on elastography(c), proven to be papillary carcinoma on FNAC. The first follow‑up image(d) showing the stability while the last follow‑up images(e and f) showing progression of the left lobe microcarcinoma and a new‑onset suspicious left‑level VI node, respectively. USG: Ultrasonography, FNAC: Fine‑needle aspiration cytology

Figure 3

High‑risk features in papillary thyroid microcarcinoma:(a) 5‑ mm nodule in the isthmus of the thyroid with invasion of thyroid capsule(mean thickness of thyroid isthmus is 3–4 mm),(b) Nodule in the posteromedial aspect of the right lobe of the thyroid invading recurrent laryngeal nerve,(c) Nodule in the left lobe of the thyroid with metastatic ipsilateral cervical node and(d) Nodule along the medial aspect of the right lobe of the thyroid invading the trachea

Figure 4

Scheme for stratification of low‑risk PTMC patients into ideal, appropriate, and inappropriate candidates for active surveillance based on fulfillment of the criteria mentioned, as proposed by Brito et al. PTMC: Papillary thyroid microcarcinoma

Figure 5

Schematic diagram showing the active surveillance strategy with the red flag signs