Endocrine Abstracts

Aim: The assessment of the disease course and selected clinicopathological factors associated with recurrence risk and the effectiveness of surgical treatment of PTC patients.

Material and Methods: The retrospective analysis of 260 PTC patients selected from 403 patients operated on for recurrent thyroid cancer between 2002 and 2018 was performed. All statistical analyses were done using the programming environment R (v. 4.0.2).

Results: PTC patients differed in terms of the primary cancer stage. Stage T3 was predominant (40.4%) followed by stage T1 (33.1%). Lymph node metastases occurred in 167 patients (64.2%), while distant metastases in 2 (0.8%). The 5-year overall survival (OS) was 100% and the 20-year OS survival exceeded 80%. 113 patients (43.5%) were operated on for recurrence more than once. They had a significantly worse OS (P = 0.038). The highest percentage of complete recovery (94.6%) was achieved in patients reoperated on once only (P < 0.001). The 5-year disease-free survival (DFS) was 60% and the 15-year DFS was 30%. The best DFS was reported in pT1a patients. DFS was not significantly different in patients staged pT1b, while it was significantly worse in stage pT2. Worse DFS was observed in older patients (age ≥ 55; P < 0.0001), in males (P = 0.004), and in patients whose thyroglobulin (Tg) levels on TSH stimulation assessed after surgery for the first recurrence exceeded 10 pg/ml (P < 0.0001). In univariate analysis, the factors associated with higher recurrence risk included male sex (P = 0.005), age ≥ 55 years (P < 0.001), primary tumor diameter of 2-4 cm (P = 0.001) and >4 cm (P = 0.021), and postoperative Tg levels >10 ng/ml (P < 0.001). Significant factors in the multivariate analysis included tumor size of 2-4 cm (P = 0.004), lymph node metastasis (P = 0.046), high Tg levels (P = 0.001) and radicality of the first surgery (P = 0.043). In the Cox regression analysis, the independent prognostic factors affecting the risk of recurrence included primary tumor diameter of 2-4 cm (P = 0.004), Tg levels >10ng/ml (P < 0.001), lymph node metastases (P = 0.046) and radicality of the first surgery (P = 0.043).

Conclusions: The significant adverse influence of primary tumor diameter (2-4 cm) on the prognosis seems to be an argument against limitation of the extent of surgery in PTC patients staged cT2N0M0 as proposed by ATA. The study confirms the significance of high postoperative Tg levels as an independent prognostic risk factor associated with locoregional recurrence. The inconclusive results of the significance of other clinicopathological factors warrant further studies.