Radioactive Iodine Therapy Decreases the Recurrence of Intermediate-Risk PTC With Low Thyroglobulin Levels

Thyroid cancer epidemiology in Ireland from 1994 to 2019 - Rising diagnoses without mortality benefit

BACKGROUND

The epidemiology and management of thyroid cancer has changed radically in the recent past, with rising international incidence of early-stage papillary thyroid cancer (PTC) in particular. In this paper, we review the epidemiology of thyroid cancer in Ireland.

METHODS

A retrospective cohort study of National Cancer Registry of Ireland data, 1994-2019.

RESULTS

Records from 4158 patients were analysed. 73 % (n = 3040) were female. The average age was 50.4 years. Patient sex did not change over time (p = 0.662), while age decreased significantly (p < 0.0001). The most common diagnoses were PTC (n = 2,905, 70 %) and follicular thyroid carcinoma (n = 549, 13 %). Incidence rose over threefold (1.8-6.2 cases/100000 person-years). The incidence of T1 PTC rose over twelvefold (0.169-2.1 cases/100000 person-years), while the incidence of stage III and IV disease did not change significantly. Five-year disease-specific survival (DSS) was 85 % and varied significantly by diagnosis - 97 % for PTC versus 5 % for anaplastic thyroid carcinoma. Survival did not change significantly over time. Male sex was a risk factor for more advanced disease (p < 0.0001) but did not independently predict overall survival except in PTC (HR 1.6, p = 0.03). The use of radioactive iodine declined markedly from 49 % to 12.5 %. RAI improved DSS for PTC patients aged over 55 years (p = 0.02) without a notable effect on survival for those under 55 years (p = 0.99).

CONCLUSION

The epidemiology and management of thyroid cancer in Ireland has changed dramatically in a manner reflective of international trends.

Decision Variables for the Use of Radioactive Iodine in Patients with Thyroid Cancer at Intermediate Risk of Recurrence

The use of radioactive iodine (RAI) after total thyroidectomy for patients at the American Thyroid Association (ATA) who are at intermediate risk of recurrence is controversial. This is due to the lack of prospective randomized trials proving a benefit to recurrence or survival of RAI therapy in this group. In the absence of such evidence, clinicians struggle to recommend for or against this therapeutic approach which frequently results in overtreatment. This review describes key elements in the decision-making process that help clinicians more comprehensively evaluate the need for RAI therapy in patients with thyroid cancer at intermediate risk of recurrence. A clear definition of the purpose of RAI therapy should be conveyed to patients. In this sense, adjuvant RAI therapy intends to decrease recurrence, and ablation therapy is used to facilitate surveillance. Better stratification of the intermediate risk category into a low-intermediate subgroup and an intermediate-high-risk subgroup results in less heterogeneity and a more precise prediction of recurrence risk. The evaluation of post-operative thyroglobulin levels may prevent the overtreatment of low-intermediate-risk patients when their thyroglobulin level is <2.5 ng/mL. the integration of tumor genomics (when available) alongside pathologic features can enhance the ability of the clinician to predict iodine concentration in thyroid cancer cells. Finally, a detailed consideration of the adverse effects of RAI, patients' comorbidities, and patient preferences will result in a patient-centered personalized approach. Systematic examination of these variables will ultimately provide a framework for making more educated decisions on the use of RAI in patients at intermediate risk of recurrence that will prevent overtreatment and minimize harm.

Controversies in the Management of Intermediate-Risk Differentiated Thyroid Cancer

BACKGROUND

Intermediate-risk thyroid cancer accounts for up to two-thirds of all cases of differentiated thyroid cancer (DTC), yet it is subject to substantial variations in risk stratification and management strategies.

METHODS

This comprehensive review examines the current controversies regarding diagnosis and management of intermediate risk DTC.

RESULTS

The evolution of risk stratification systems is discussed, highlighting limitations such as heterogeneity in patient cohorts, variability in outcome definitions, and the need for more precise risk estimation tools incorporating genetic profiles and individual risk modifiers. The role of radioactive iodine therapy in intermediate-risk DTC is examined, considering evolving evidence, conflicting study results, and the necessity for personalized treatment decisions based on risk modifiers, potential morbidity, and patient preferences. Furthermore, the shift from total thyroidectomy to lobectomy in certain intermediate-risk cases is explored, emphasizing the need for tailored surgical approaches and the impact on long-term outcomes, recurrence rates, and quality of life.

CONCLUSION

Management of intermediate-risk DTC remains controversial. This review summarizes current evidence to aid decision-making. Further research, prospective trials, and collaboration are crucial to address these complexities and personalize care for patients.

Predictors of distant metastatic recurrence in intermediate-risk papillary thyroid carcinoma

BACKGROUND

Patients with intermediate-risk papillary thyroid carcinoma (PTC) have a favorable prognosis with standard treatment of total thyroidectomy (TT) and adjuvant radioactive iodine therapy (RAIT). However, the benefits of TT or adjuvant RAIT remain undetermined, and they are often omitted in Japan. We investigated risk factors for life-threatening distant recurrence in patients with intermediate-risk PTC who are optimal candidates for adjuvant RAIT.

PATIENTS AND METHODS

Outcomes without RAIT were retrospectively examined in 4030 intermediate-risk conventional PTC cases underwent initial surgery from 2005 to 22 (IRB approval 20200709-1).

RESULTS

Lobectomy (LT) and TT was performed in 11.5% and 88.5%, respectively. Recurrent laryngeal nerve paralysis and hypoparathyroidism was less commonly observed in LT (1.3% and 0%) than TT (2.4% and 3.5 %). Fifty-six cases (1.4%) had distant recurrence. Recurrence-free survival rates at 10 years was 93.5%. There was no significant difference in recurrence rate between LT and TT. Age ≥55, cN1b, and tumor diameter >30 mm significantly associated with distant recurrence. There was a strong relationship between the number of positive risk factors and recurrence; the distant recurrence rate in cases of 0, 1, 2, and 3 positive factors was 0.3% (4/1203), 1.3% (25/1889), 2.7% (23/830) and 7.1% (4/52) (HR 6.46 (2.34-17.86), Log-rank <0.001).

CONCLUSION

For intermediate-risk conventional PTC, there is no difference in prognosis even if LT was selectively conducted. However, in patients with risk factors for distant metastatic recurrence, such as age ≥55 years, cN1b, and tumor size >30 mm, adjuvant RAIT was considered eligible.

Pediatric Papillary Thyroid Carcinoma: Outcomes After Surgery Without Adjuvant Radioactive Iodine

CONTEXT

Pediatric papillary thyroid carcinoma (PTC) is usually treated with total thyroidectomy followed by radioactive iodine (RAI). Recently, RAI is being used more selectively based on surgical pathology and postoperative dynamic risk stratification (DRS).

OBJECTIVE

To describe patients with pediatric PTC not initially treated with RAI and their disease outcomes.

METHODS

This was an ambispective study at a tertiary cancer center of patients < 19 years diagnosed from 1/1/1990 to 12/31/2021 with stage I PTC who intentionally were not treated with RAI within a year of diagnosis. We assessed clinical characteristics, management, and disease outcomes using DRS.

RESULTS

Of 490 PTC patients, we identified 93 eligible patients (median age at diagnosis 16y; 87% female), including 46 (49%) with cervical lymph node metastases. Initial management included: total thyroidectomy ± neck dissection (n=69, 75%), lobectomy ± neck dissection (n=20, 21%), or a Sistrunk procedure for ectopic PTC (n=4, 4%). After a median follow-up of 5.5 years (range 1-26), most patients (85/93; 91%) remained disease-free with no further therapy. Persistent (n=5) or recurrent (n=3) disease was found in 9% of the entire cohort. Four patients ultimately received RAI, of which only one clearly benefited, and additional surgery was performed or planned in four patients, two of whom had an excellent response at last follow-up.

CONCLUSIONS

Selected pediatric PTC patients, even those with lymph node metastases, may not require therapeutic 131I and can avoid the unnecessary risks of RAI while still benefitting from the excellent long-term outcomes that are well-described for this disease.

Current practice in intermediate risk differentiated thyroid cancer - a review

Although the overall prognosis for differentiated thyroid cancer (DTC) is excellent, a subset of patients will experience disease recurrence or may not respond to standard treatments. In recent years, DTC management has become more personalized in order to enhance treatment efficacy and avoid unnecessary interventions.In this context, major guidelines recommend post-surgery staging to assess the risk of disease persistence, recurrence, and mortality. Consequently, risk stratification becomes pivotal in determining the necessity of postoperative adjuvant therapy, which may include radioiodine therapy (RIT), the degree of TSH suppression, additional imaging studies, and the frequency of follow-up.However, the intermediate risk of recurrence is a highly heterogeneous category that encompasses various risk criteria, often combined, resulting in varying degrees of aggressiveness and a recurrence risk ranging from 5 to 20%. Furthermore, there is not enough long-term prognosis data for these patients. Unlike low- and high-risk DTC, the available literature is contradictory, and there is no consensus regarding adjuvant therapy.We aim to provide an overview of intermediate-risk differentiated thyroid cancer, focusing on criteria to consider when deciding on adjuvant therapy in the current context of personalized approach, including molecular analysis to enhance the accuracy of patient management.

Impact of radioiodine therapy on recurrence and survival outcomes in intermediate-risk papillary thyroid carcinoma -A systematic review and meta-analysis

OBJECTIVE

The utility of radioiodine (RAI) therapy in intermediate-risk papillary thyroid carcinoma (PTC) remains a topic of ongoing discussion. This systematic review and meta-analysis aimed to consolidate existing evidence on the impact of postoperative RAI therapy on recurrence and survival outcomes in intermediate-risk PTC.

METHODS

A literature search was performed using relevant keywords in PubMed, Scopus, and EMBASE. Articles from January 2008 to March 2023 were included. Odds ratios (ORs) and hazard ratios (HRs) were extracted from the individual articles, and pooled estimates were generated using meta-analysis.

RESULTS

Eleven articles comprising 56,266 intermediate-risk PTC patients were included. 41,530 (73.8%) patients underwent postoperative RAI therapy, while 14,736 (26.2%) patients were kept on no-RAI (NOI) follow-up. No significant reduction in rates of structural disease recurrence was noted with RAI therapy in comparison to NOI follow-up (pooled univariate OR, 0.73, 95% confidence interval [CI], 0.29-1.87, I2  = 75%). RAI therapy was not a significant predictor of better recurrence-free survival (pooled multivariate HR, 0.21; 95% CI, 0.01-3.74, I2  = 94%). Interestingly, RAI therapy was associated with an overall survival benefit compared to NOI follow-up (pooled multivariate HR, 0.63; 95% CI, 0.48-0.82, I2  = 79%).

CONCLUSIONS

This meta-analysis did not establish a conclusive benefit of RAI therapy in preventing structural disease recurrence or improving recurrence-free survival in intermediate-risk PTC. However, these results need to be interpreted with caution owing to significant heterogeneity in the existing literature. A prospective, randomised clinical trial is the need of the hour to better understand the effect of RAI therapy on long-term outcomes.

Higher adjuvant radioactive iodine therapy dosage helps intermediate-risk papillary thyroid carcinoma patients achieve better therapeutic effect

Objective

This retrospective study aims to evaluate the therapeutic effect of varying dosages of adjuvant radioactive iodine (RAI) therapy on intermediate-risk papillary thyroid carcinoma (PTC) patients.

Methods

This retrospective study involved a total of 427 intermediate-risk PTC patients, out of which 202 received a 3.7GBq dosage of RAI, and 225 received a 5.55GBq dosage. The evaluation involved assessing the therapeutic outcomes, number of treatment cycles, and successful remnant ablation rates in both dose groups, six months post-adjuvant RAI therapy. Univariate and multivariate logistic regression analyses were employed to identify factors linked with excellent response (ER). Following this, prognostic nomograms were constructed to provide a visual representation of the prediction models. Calibration curves, the concordance index (C-index), and the receiver operating characteristic (ROC) curve were employed to evaluate the predictive performance of these nomograms. The Hosmer-Lemeshow test was applied to assess the models' goodness-of-fit. Additionally, the clinical utility of the prognostic nomograms was appraised through decision curve analysis (DCA).

Results

The high-dose (HD) group exhibited significantly higher proportions of ER, single treatment cycles, and successful remnant ablation rates (p<0.05). Being male, receiving a 3.7GBq dose, having an N1b stage, an sTg level ≥10ng/ml, or an sTg/TSH ratio ≥0.11 were independent risk factors for Non-ER. Two prognostic nomograms, "sTg Nomogram" and "sTg/TSH Nomogram", were established. The ranking of factors contributing to ER, in descending order, included the sTg or sTg/TSH ratio, N stage, therapy dosage, sex, and soft tissue invasion. The "sTg/TSH Nomogram" demonstrated a higher C-index compared to the "sTg Nomogram". The calibration curves indicated excellent calibration for both nomograms. DCA demonstrated that the net benefit of the "sTg/TSH Nomogram" was higher than that of the "sTg Nomogram".

Conclusion

Higher initial RAI therapy doses can improve therapeutic efficacy for intermediate-risk PTC patients. The developed nomograms, particularly the "sTg/TSH Nomogram", could assist clinicians in optimal therapeutic decision-making.

Comparison of Treatment and Prognosis Between Follicular Variant Papillary Thyroid Carcinoma and Classical Papillary Thyroid Carcinoma

This cohort study evaluated the associations of different treatments with the prognosis of follicular variant papillary thyroid carcinoma (FVPTC) and classical papillary thyroid carcinoma (CPTC) patients. The data of 69034 PTC patients were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. The 5-year mortality of CPTC and FVPTC patients receiving surgery, radiation and combination therapy were compared. The univariable and multivariable cox proportional risk models explored the associations between different treatments and the 5-year mortality in CPTC and FVPTC patients. The 5-year mortality of CPTC patients was 2.81% and FVPTC patients was 2.47%. Compared with CPTC receiving lobectomy and/or isthmectomy, those not receiving surgery were associated with increased risk of 5-year mortality [Hazards ratio (HR)=3.27, 95% confidence interval (CI): 2.55-4.20] while total thyroidectomy was correlated with reduced risk of 5-year mortality (HR=0.67, 95%CI: 0.55-0.80). Radioactive iodine (RAI) was linked with decreased risk of 5-year mortality in CPTC patients (HR=0.57, 95%CI: 0.50-0.65). CPTC patients undergoing both surgery and radiation were related to decreased risk of 5-year mortality compared with those receiving surgery only (HR=0.55, 95%CI: 0.48-0.63). CPTC patients receiving neither surgery nor radiation (HR=4.53, 95%CI: 3.72-5.51) or those receiving radiation (HR=1.98, 95%CI: 1.13-3.48) were correlated with elevated risk of 5-year mortality. The elevated risk of 5-year mortality in FVPTC patients was reduced in those undergoing RAI (HR=0.63, 95%CI: 0.51-0.76). In conclusion, combination therapy was associated with decreased risk of 5-year mortality in CPTC and FVPTC patients, which might provide a reference for the management of these patients.