Prognosis and ablation success in thyroid cancer: overcoming the challenges of incomplete clinical profiles.

Background: Differentiated thyroid carcinoma (DTC) is managed by surgery followed by radioiodine (RAI) therapy in most intermediate and high-risk patients. Most nonmetastatic patients have excellent treatment responses and have long-term disease-free status. A lack of comprehensive medical services in resource-limited nation leads to attrition of critical clinical prognostication information. This study aimed to identify readily available clinical, biochemical, and histopathological parameters to predict remnant ablation success and long-term outcomes.

Methods: The study included DTC patients who underwent RAI after surgery. Ablation success was determined by thyroglobulin (Tg) and whole-body radioiodine scan. Patients were followed for at least 5 years to assess biochemical incomplete response (BIR) and structural recurrence.

Results: The study included 383 patients (a mean age of 37.8 ± 12.9 years). Successful ablation was noted in 251 (65.5%). High preablative stimulated serum Tg (presTg), papillary variants, and central and lateral compartment lymph nodal metastases were associated with ablation failure. PresTg (P < 0.001) was the most significant predictor. After a 102.9 ± 34.5 months follow-up, 280 (73.1%) patients were disease-free. BIR and structural recurrence were noted in 103 and 32 patients. PresTg (8.1 ± 27.7 vs. 92.3 ± 99.9 ng/ml), ATg (112.9 ± 389.8 vs. 43.2 ± 89.8 IU/ml), papillary variant, central [109 (66.1%) vs. 56 (33.9%)], and lateral compartment [65 (63.7%) vs. 37 (36.3%) lymph nodal metastases were associated (P < 0.05) with BIR. PresTg >10.5 has a sensitivity and specificity of 86.6 and 86.0% for predicting BIR. Patients with successful remnant ablation and a presTg level <10.5 ng/ml had a low risk of long-term disease recurrence (less than 5%).

Conclusion: This ambispective study found that successful ablation and long-term disease-free survival were achievable in a significant proportion of DTC patients. BIR (26.9%) and structural recurrence (8.4%) were not uncommon. PresTg levels emerged as a crucial predictor of ablation success and subsequent outcomes. In resource-limited regions, presTg levels and ablation failure can aid in optimizing treatment strategies and improving patient care.