Disease-related and treatment-related unfavorable events in the management of low-risk papillary microcarcinoma of the thyroid by active surveillance versus immediate surgery

Active surveillance is emerging as a viable clinical alternative to immediate surgery in the management of low-risk papillary thyroid microcarcinoma (PMC). While indolent PMC may be present in up to 10% of the United States population, only a small proportion of this subclinical disease evolves into clinically significant disease (1-3). Instead, the vast majority of lesions are asymptomatic and detected incidentally by imaging studies (neck US, CT, MRI) done for unrelated reasons (4). Active surveillance has arisen as an attractive alternative management strategy because the natural history of PMC is one of slow growing or stable tumors with low rates of lymph node metastasis, and extremely low risk of distant metastasis and disease-related mortality. Even more importantly, a delayed surgical approach has proven to be a very effective salvage therapy for the few patients who demonstrate structural disease progression (5). Several recent reports continue to demonstrate that active surveillance is associated with excellent clinical outcomes (5-8).