Pitfalls in the 2017 TNM Classification of Thyroid Carcinoma

Abstract

The objective of this article is to detail the 2017 tumor-node-metastasis (TNM) staging criteria for thyroid cancer. The literature presents only few contributions, with controversial results, about comparison between previous and the new TNM systems. The 2017 TNM classification categorizes either thyroid carcinomas only limited to the gland either carcinomas macroscopically infiltrating into defined anatomical structures. The "minimal extrathyroid spread" into the perithyroidal adipose tissue no longer appears as a classification parameter in the new TNM. In the present paper is discussed for the pT categories pT1a, pT1b, pT2, and pT3a. In detail, the T-categories pT1a, pT1b, pT2, and pT3a are each subdivided into true thyroid-restricted carcinomas (pT1a1, pT1b1, pT2a1, and pT3a1) and "minimal extrathyroid proliferation" carcinomas (pT1a2, pT1b2, pT2b, and pT3a2). As a basis, a strict definition of the "minimal extrathyroid propagation" of thyroid carcinomas is essential. Although the suggestion made with the additional substrate characterization makes the work of the pathologist more intricate in daily use, standardized fundamentals for demonstrating or excluding the prognostic and therapeutic relevance concerning a "minimal extrathyroid extension" in thyroid carcinoma appear to be necessary. PREFACEMany efforts have been made to reach a higher accuracy in the tumor staging classifications (1). Tumor staging classifications demand to be constantly updated to latest clinical, anatomic, numeric criterion, pathological, molecular biology, genetics and biochemical findings in order to fulfill their function of internationally accepted standardization and comparability of objective pathological data as the basis for managing patients with malignant diseases (1).Specific standards have to be considered for the determination of the anatomical spread of malignant tumors by the clinical tumor-node-metastasis (cTNM) and pathological tumor-node-J Endocr Surg. 2018 Jun;18(2):98-109 https://doi.

Strap muscle invasion in differentiated thyroid cancer does not impact disease-specific survival: a population-based study

“…Invasion of strap muscle in any degree may not have significant survival impact due to the relative complexity of posterior anatomical structures such as trachea, recurrent laryngeal nerve, and prevertebral fascia. Critical laryngotracheal structure invasion leads to a higher possibility of incomplete resection and therefore to higher clinical recurrence and poorer prognosis 9 . On the other hand, strap muscles can be relatively easily resected in the presence of tumor invasion 13 , 22 , accounting for their lack of significant impact on DSS.…”

Survey of Korean head and neck surgeons and endocrinologists for the surgical extent of 1.5 and 2.5 cm papillary thyroid carcinoma

“…Suspected anterior gross ETE indicated that anterior strap muscle invasion was suspected on US. Gross strap muscle invasion (T3b) is associated with a higher risk of positive resection margins, larger tumor size, higher recurrence rate, and lower disease survival rate (17)(18)(19). Therefore, when anterior gross ETE is suspected, both surgeons and endocrinologists recommend TT in many cases.…”