BRAF Mutation in Papillary Thyroid Microcarcinoma: The Promise of Better Risk Management

Excerpt

How to manage risk in cases of papillary thyroid microcarcinomas (PTMC), defined as papillary thyroid carcinomas (PTC) of size ≤1.0 cm,1 has been controversial. Conventional wisdom dictates that these are low-risk cancers that are virtually free of mortality and should therefore be conservatively managed. Also in support of conservative management of PTMC are the potentially adverse outcomes of aggressive treatments, such as surgical damage to the recurrent laryngeal nerve and parathyroid glands from thyroid surgery and the development of second primary cancers from radioiodine treatments.2,3 It is even acceptable in some practices to forgo treatments of patients with PTMC.4 On the other side of the coin, however, is the well-recognized risk that PTMC can progress with a significant recurrence rate and even mortality in some patients.5‐7 This is true particularly in the presence of high-risk clinicopathological factors that are classically known to be associated with a poor prognosis in conventional thyroid cancers. These include extrathyroidal extension, lymph node metastasis, and high TNM stages.8‐12 Given these divided results, it appears that a subgroup of PTMC is inherently aggressive and predestined to progress. Although opinions often differ on how to manage PTMC,6,7 there is little argument that the subgroup of patients with PTMC with high potential for poor prognosis should receive relatively aggressive initial treatments (e.g., total thyroidectomy, central neck dissection, or radioiodine ablation as opposed to lobectomy, no neck dissection, or no radioiodine ablation, respectively) and vigilant follow-up for disease recurrence after initial treatments. The challenge, however, often lies in the difficulty of identifying this subgroup of PTMC based on the classical clinicopathological criteria, particularly preoperatively, when the pathological characteristics of the tumor are virtually unknown. Therefore, it is often not a straightforward task to determine the appropriate level and extent of the initial treatment for an individual patient with PTMC that has been identified ultrasonographically and confirmed cytologically. …