Chereau N, et al. - The prognosis of 4 subgroups of pT3 differentiated thyroid cancers (DTCs) (papillary, PTC; or follicular, FTC) were examined in a homogeneously managed pT3-differentiated thyroid carcinoma population. Regardless of the size of the tumor, the risk of lymph node (LN) involvement was high and similar for the DTC patients with minimal extrathyroidal extension (ETE) except for microcarcinoma. The association of a tumor size of > 4 cm and ETE were correlated with a poor prognosis and ought to justify the classification of these cases as a high-risk group. Other pT3 patients with no LN metastases could be individualized as a low-risk group.

Methods

• The researchers reviewed the data of patients who underwent surgery for pT3 DTC between 1978 and 2015 in a surgical department specialized in endocrine surgery.
• They classified patients into 4 groups as follows:
  • The pT3a (≤10 mm with ETE),
  • pT3b (10-40 mm with ETE),
  • pT3c (> 40 mm without ETE), and
  • pT3d groups (> 40 mm with ETE).
• The Kaplan-Meier method was used to examine recurrence-free survival (RFS).

Results

• The researchers included 1,088 patients with pT3 DTC.
• Out of these, 311 (29%) had pT3a; 548 (50%), pT3b; 165 (15%), pT3c; and 64 (6%), pT3d.
• Metastatic LNs were more frequent in the pT3b and pT3d groups (61 and 61%, respectively) than in the other groups (44% pT3a and 10% pT3c; p < 0.001), for the 916 patients with lymph node (LN) dissection.
• Recurrence occurred in 169 patients with T3 tumors (16%), including 18 with pT3a (6%), 100 with pT3b (18%), 20 with pT3c (12%), and 31 with pT3d (48%) during the median follow-up period of 9 years (range, 2–38 years).
• Multivariate analysis revealed that factors associated with an increased risk of recurrence were LN metastases (< 0.0001), extranodal extension (p=0.03), FTC (vs PTC) (p=0.006), pT3b (p=0.016), and pT3d (p=0.047).
• For the pT3a, pT3b, pT3c, and pT3d groups, the 5-year RFS rates were 94.5, 82.2, 91.1, and 50.3%, respectively (p < 0.01).