Factors predicting the risk of biochemical incomplete response in well-differentiated thyroid cancer after total thyroidectomy

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 ng/ml 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.

Predicting factors and clinical outcome of biochemical incomplete response in middle eastern differentiated thyroid carcinoma

PURPOSE

The aim of this study was evaluate biochemical incomplete response (BIR) in Middle Eastern differentiated thyroid cancer (DTC), identify factors that could predict BIR before radioactive iodine (RAI) ablation and to investigate the long-term clinical outcome of DTC patient exhibiting BIR to initial therapy.

METHODS

We retrospectively evaluated 1286 DTCs from Middle Eastern ethnicity who underwent total thyroidectomy and RAI therapy. Demograpic and clinico-pathological factors predicting BIR were evaluated. The outcome of these patients was analyzed using primary outcome of structural disease and disease-free survival (DFS).

RESULTS

With a median follow-up of 10 years, 266 (20.7%) patients had BIR. High pre-ablation stimulated thyroglobulin (presTg), presence of lymph node metastasis, male gender and delayed initial RAI therapy (≥3 months) after thyroidectomy were significant independent predictors of BIR. Upon evaluating long-term clinical outcomes in 266 patients with BIR, we found 36.8% of patients developed structural disease. Male sex (OR = 1.56; 95% CI = 1.05-2.30; p = 0.0272) and increasing Tg after initial therapy (OR = 4.25; 95% CI = 1.93-10.82; p = 0.0001) were independent risk factors for structural disease in patients with BIR. DFS was significantly worse if both these risk factors existed concomitantly (p < 0.0001).

CONCLUSION

To achieve the fair efficacy of RAI therapy, early prediction of BIR before RAI ablation is desirable. Our finding of the clinico-pathological factors (high presTg level, LNM, delayed RAI therapy and male gender) could serve as easy and robust early predictors of BIR. In addition, DTC patients exhibiting BIR had a high risk of structural disease and hence personalized management approach would be preferable for BIR patients to ensure best clinical outcome.

The American Thyroid Association risk stratification and long-term outcomes of differentiated thyroid cancer: a 20-year follow-up of patients in Saudi Arabia

Background

Studies have reported differing factors associated with poor outcomes in patients with differentiated thyroid cancer (DTC). We aimed to describe our 20 years of experience in the management of thyroid cancer (TC) and identify predictors of treatment outcomes.

Methods

We conducted a retrospective review of medical records of patients with TC seen in the Thyroid Center at King Saud University Medical City (KSUMC) in Riyadh, Saudi Arabia, between the years 2000 and 2020. Demographic and clinical data including pathological characteristics were collected. The American Thyroid Association (ATA) risk stratification was determined for all patients at the postoperative period as well as the response to therapy at the final follow-up visit.

Results

A total of 674 patients (mean age: 47.21 years) with TC, 571 (84.7%) of which were women, were included. There were 404 (60.0%) patients with ATA low risk, 127 (18.8%) with intermediate risk, and 143 (21.2%) with high-risk histology. Overall, 461 patients (68.4%) had an excellent response to treatment, 65 (9.6%) had an indeterminate response, 83 (12.3%) had a biochemical incomplete response, and 65 (9.6%) had a structural incomplete response. Patients who had an excellent response were mostly ATA low risk (n = 318 of 431, 68.1%), whereas 40 of 65 patients (61.5%) of those with ATA high-risk histology had a structural incomplete response to treatment. There were significantly more women who had an excellent response compared with men. Obesity, lymphovascular invasion, and size of the tumor were significant predictors of worse outcomes to therapy.

Conclusion

Tumor size, lymphovascular invasion, and obesity are strong predictors of a worse response to therapy among patients with TC. Patients with obesity should be carefully followed up regardless of their risk stratification in light of the recent compelling evidence associating obesity with thyroid cancer and its higher risk of a worse disease outcome. ATA risk stratification is well correlated with patient long-term outcomes.