Long-term consequence of elevated thyroglobulin in differentiated thyroid cancer

Radioactive Iodine Therapy in Differentiated Thyroid Cancer: Summary of the Korean Thyroid Association Guidelines 2024 from Nuclear Medicine Perspective, Part-II

Thyroid cancer, one of the most common endocrine tumors, generally has a favorable prognosis but remains a significant medical and societal concern due to its high incidence. Early diagnosis and treatment of differentiated thyroid cancer (DTC) significantly affect long-term outcomes, requiring the selection and application of appropriate initial treatments to improve prognosis and quality of life. Recent advances in technology and health information systems have enhanced our understanding of the molecular genetics of thyroid cancer, facilitating the identification of aggressive subgroups and enabling the accumulation of research on risk factors through big data. The Korean Thyroid Association (KTA) has revised the "KTA Guidelines on the Management of Differentiated Thyroid Cancers 2024" to incorporate these advances, which were developed by a multidisciplinary team and underwent extensive review and approval processes by various academic societies. This article summarizes the 2024 KTA guidelines for radioactive iodine (RAI) therapy in patients with DTC, written by the Nuclear Medicine members of the KTA Guideline Committee, and covers RAI therapy as initial management of DTC and RAI therapy in advanced thyroid cancer.

Efficacy of Empirical Radioiodine Therapy in Patients with Differentiated Thyroid Cancer and Elevated Serum Thyroglobulin without Evidence of Structural Disease: A Propensity Score Analysis

We assessed the outcome of administration of empiric radioactive iodine (RAI) therapy to patients with differentiated thyroid cancer (DTC), in a propensity-score-matched cohort of patients with biochemical incomplete response (BIR) and without evidence of structural disease. We retrospectively evaluated 820 DTC patients without distant metastases, who underwent total thyroidectomy followed by RAI therapy, with available BIR at 12 months and follow-up evaluations. The patients were categorized according to the administration of empiric therapy (ET). To account for differences between patients with (n = 119) and without (n = 701) ET, a propensity-score-matched cohort of 119 ET and 119 no-ET patients was created. The need for additional therapy and the occurrence of structural disease were considered as end-points. During a median follow-up of 53 months (range 3-285), 57 events occurred (24% cumulative event rate). The rate of events was significantly higher in the no-ET compared to the ET patients (30% vs. 18% p < 0.001). The multivariate Cox analysis identified age (p < 0.01), pre-therapy Tg (p < 0.05) and empiric RAI therapy (p < 0.01) as predictors of outcome. The Kaplan-Meier analysis found that progression-free survival was lower in no-ET patients compared to the ET group (p < 0.01). In patients with DTC treated with surgery and RAI, and with biochemical incomplete response at the 12-month evaluation, their prognosis seemed to be affected by Tg values and the empiric treatment. The identification of candidates for this approach may improve prognosis.

Serum thyroglobulin testing after thyroid lobectomy in patients with 1-4 cm papillary thyroid carcinoma

BACKGROUND

The role of measuring serum thyroglobulin (Tg) levels in patients who have undergone lobectomy has not been proven. The goal of this research is to see if serum Tg levels can predict the recurrence of papillary thyroid carcinoma (PTC) after lobectomy.

METHODS

The 463 patients with 1-4 cm PTC who underwent lobectomy between January 2005 and December 2012, were included in this retrospective cohort study. Postoperative serum Tg levels and neck ultrasound were evaluated every 6-12 months after lobectomy during a median 7.8-year follow-up period. The receiver operating characteristic (ROC) curve and its area under the ROC curve (AUC) was used to assess the diagnostic performance of serum Tg levels.

RESULTS

During the follow-up, the structural recurrent disease was confirmed in 30 patients (6.5%). The serum Tg levels measured by initial Tg, maximal Tg, and last Tg did not differ statistically between the recurrence and non-recurrence groups. According to our findings, serial patterns of serum maximal Tg variations in 30 patients with recurrence showed no obvious trend and no rising trend toward recurrence before detecting recurrence. The AUC was 54.5% (IQR 43.1%-65.9%) in the ROC curve analysis, indicating that it was not significantly different from the random classifier.

CONCLUSION

Serum Tg levels did not differ significantly between the recurrence and non-recurrence groups, and there was no tendency for the recurrence group to increase Tg levels. In patients with PTC who underwent lobectomy, monitoring Tg levels regularly provides little benefit in predicting recurrence.

Circulating Biomarkers in Thyroid Cancer

Thyroid cancer is the most important endocrine cancer with increasing incidence. While thyroid cancers, especially papillary thyroid cancers, are known to exhibit generally a favorable outcome with excellent survival rates, some thyroid cancers are more aggressive with a poor prognosis. Several different biomarkers have been introduced for the diagnosis of disease, identification of tumor load, assessment of therapy response, and the detection of recurrence during follow-up of the thyroid cancer patients. This chapter gives a brief overview of the circulating biomarkers used in thyroid cancer patients.

Contemporary Debates in Adult Papillary Thyroid Cancer Management

An ever-increasing population of patients with papillary thyroid cancer is engaging with health care systems around the world. Numerous questions about optimal management have arisen that challenge conventional paradigms. This is particularly the case for patients with low-risk disease, who comprise most new patients. At the same time, new therapies for patients with advanced disease are also being introduced, which may have the potential to prolong life. This review discusses selected controversial issues in adult papillary thyroid cancer management at both ends of the disease spectrum. These topics include: (i) the role of active surveillance for small papillary cancers; (ii) the extent of surgery in low-risk disease (lobectomy vs total thyroidectomy); (iii) the role of postoperative remnant ablation with radioiodine; (iv) optimal follow-up strategies in patients, especially those who have only undergone lobectomy; and (v) new therapies for advanced disease. Although our current management is hampered by the lack of large randomized controlled trials, we are fortunate that data from ongoing trials will be available within the next few years. This information should provide additional evidence that will decrease morbidity in low-risk patients and improve outcomes in those with distant metastatic disease.

Surveillance of patients with differentiated thyroid cancer and indeterminate response: a longitudinal study on basal thyroglobulin trend

PURPOSE

This is a longitudinal study of retrospective data aimed at verifying whether repeated measurements of serum non-stimulated thyroglobulin (Tg) allow the prediction of persistent disease in patients with differentiated thyroid cancer (DTC) and indeterminate response.

METHODS

We examined 145 DTC patients with indeterminate response to therapy followed up for a median time of 68 months. Tg measurements and neck ultrasound (US) were performed every 6-12 months. The changes over time of repeated measurements of basal Tg were analyzed through the multilevel linear regression.

RESULTS

Seventy (48.3%) out of 145 patients spontaneously achieved an excellent response, while persistent indeterminate response was observed in 62 (42.7%) patients. The remaining 13 (9.0%) patients had progression: 3/13 with biochemical disease and 10/13 with structural disease. Tg steadily increased in patients with progressive disease (mean percentage change + 27.1% at each follow-up visit), while Tg decreased in patients without any evidence of progression (mean percentage change - 8.8%). This different trend between the two groups was not related to either different values of median TSH at baseline (0.32 vs 0.28 mIU/l, respectively) or to different trend of TSH during follow-up (p = 0.76). Basal Tg values did not increase in three out of ten patients with structural disease that was identified by neck US.

CONCLUSIONS

The importance of the study is that, in DTC patients with indeterminate response, rising values of unstimulated Tg, independently from the basal levels, may be useful to identify patients with progressive disease. These results are also useful to avoid unnecessary TSH stimulation.

UNFAVORABLE RESPONSES TO RADIOIODINE THERAPY IN N1B PAPILLARY THYROID CANCER: A PROPENSITY SCORE MATCHING STUDY

Objective: Regional nodal metastases carry prognostic significance in papillary thyroid cancer (PTC). However, whether different locational nodal metastases correlate with different therapeutic responses remains controversial. We innovatively applied the response to therapy restratification system to evaluate the dynamic disease status after surgery and radioactive iodine (RAI) therapy in PTC patients with different locational nodal metastases. Methods: A total of 585 nondistant-metastatic PTC patients who underwent total thyroidectomy and RAI therapy were retrospectively enrolled. Patients with nodal metastases were categorized into N1a and N1b groups. Propensity score matching was used to balance the bias between the 2 groups. Therapeutic responses were dynamically evaluated, and responses to RAI therapy were classified into excellent (ER), indeterminate (IDR), biochemical incomplete (BIR) and structural incomplete response (SIR). Results: N1b group patients showed a significantly higher pre-ablation stimulated thyroglobulin (Ps-Tg) level than N1a group patients (7.4 ng/mL versus 3.2ng/mL, P<.001). After RAI therapy, N1b group patients took a longer time to achieve ER (9.86 months versus 3.29 months, P<.001) and exhibited a higher proportion of non-ER (IDR, BIR, and SIR) (39.15% versus 17.46%, P<.001) compared to N1a group patients. In logistic regression, N1b and Ps-Tg ≥10 ng/mL were confirmed to be independent factors predicting non-ER (odds ratio: 2.591, and 9.196, respectively). In Cox regression, patients with N1b disease and Ps-Tg ≥10 ng/mL showed significantly lower hazards for achieving ER (hazard ratio: 0.564, and 0.223, respectively). Conclusion: N1b PTC patients showed inferior responses to surgery and RAI therapy compared to N1a patients. N1b was confirmed to be an independent factor predicting unfavorable responses to RAI therapy. Abbreviations: AJCC = American Joint Committee on Cancer; ATA = American Thyroid Association; BIR = biochemical incomplete response; BRAF^V600E = proto-oncogene B-Raf V600E mutation; CI = confidence interval; CT = computed tomography; DNA = deoxyribonucleic acid; DTC = differentiated thyroid cancer; ER = excellent response; ETE = extrathyroidal extension; HR = hazard ratio; IDR = indeterminate response; LNM = lymph node metastasis; N1a = central cervical LNM; N1b = lateral cervical LNM; OR = odds ratio; PSM = propensity score matching; Ps-Tg = pre-ablation stimulated thyroglobulin; PTC = papillary thyroid cancer; RAI = radioactive iodine; SIR = structural incomplete response; Tg = thyroglobulin; TgAb = thyroglobulin antibody; TSH = thyroid-stimulating hormone.

Time trends of thyroglobulin antibody in ablated papillary thyroid carcinoma patients: Can we predict the rate of negative conversion?

OBJECTIVES

Persistence of thyroglobulin antibody (TgAb) in patients with papillary thyroid carcinoma (PTC) years after total thyroidectomy (TT) followed by ablation occurs even without any evidence of structural disease. Few studies have studied the natural course of TgAb positivity and factors that may influence this course. The present study evaluated the time trends of TgAb in ablated PTC patients and aimed to identify the predictive factors for the rate of negative conversion of TgAb.

MATERIALS AND METHODS

Overall, 1279 patients who underwent TT and subsequent ablation for PTC, with available data on thyroid peroxidase Ab (TPOAb) and TgAb prior to surgery (preop-) and ablation (abl-) were enrolled. Patients with initial distant metastasis or recurrence during follow-up were excluded.

RESULTS AND CONCLUSION

Preop-TgAb was positive in 24.9% of patients (n = 319), whereas abl-TgAb positivity decreased to 12.8% (n = 164). In 164 patients positive for abl-TgAb, TgAb in patients with higher abl-TgAb levels decreased more gradually than those observed in patients with lower abl-TgAb levels (p < 0.001). Furthermore, in patients within the same range of abl-TgAb levels, patients positive for abl-TPOAb had a higher rate of negative conversion of TgAb compared with negative patients for abl-TPOAb (log rank p < 0.001). TPOAb significantly increased the rate of negative conversion in multivariate analysis adjusted for abl-TgAb (odds ratio 1.59, 95% confidence interval 1.11-2.28, p = 0.011). This study clearly showed that abl-TgAb titers and abl-TPOAb status can predict the rate of negative conversion. These findings can guide the optimal timing for additional examination in patients positive for TgAb during follow-up.

Outcome of Patients With Differentiated Thyroid Cancer Treated With 131-Iodine on the Basis of a Detectable Serum Thyroglobulin Level After Initial Treatment

Background: In patients with differentiated thyroid cancer (DTC) and raising serum thyroglobulin (Tg) after total or near-total thyroidectomy and ¹³¹I remnant ablation an empiric ¹³¹I therapy may be considered. However, outcome data after empiric therapy in did not show a clear evidence of improved survival. We assessed the efficacy of such empiric ¹³¹I therapy in patients with DTC and evaluated the long-term outcome. Methods: A total of 100 patients with DTC showing raised Tg level during follow-up after thyroidectomy and ¹³¹I ablation were treated with a further ¹³¹I therapy (6.1 ± 1.7 GBq). Whole-body scan (WBS) was performed 5-7 days after therapy. Tg value at 12 months after ¹³¹I therapy was considered as an indicator of treatment response: ≤1.5 ng/ml complete remission (CR), >50% decrease partial remission (PR), higher than pre-therapy progression disease (PD), all other cases stable disease (SD). Patients were followed-up for 96 ± 75 months. Results: After 12 months, 62% of patients were in CR, 16% in PR, 8% in SD, and 14% in PD. WBS was positive in 41% of patients and negative in 59% (P = NS). Among patients with local recurrences at WBS 89% showed either CR or PR, while 71% of patients with distant metastases were in SD or PD (P < 0.001). Distant metastases at WBS (P < 0.05), CR (P < 0.0001), and CR + PR (P < 0.0001) were predictors of both progression free survival and overall survival. Conclusion: There is a beneficial effect of ¹³¹I therapy on outcome of patients with DTC treated on the basis of elevated Tg value. In these patients, survival is affected by achievement of CR or PR at 12 months evaluation after ¹³¹I therapy and by the presence of distant metastases at WBS.

Value of the Postablative Thyroglobulin Measurements for Assessment of Disease-Free Status in Patients with Differentiated Thyroid Cancer

Aim:

The aim of the study is to evaluate the value of thyroid-stimulating hormone (TSH)-stimulated thyroglobulin (sTg) measurements by the end of the 1^st-year postablation in differentiated thyroid cancer (DTC) patients with biochemical non complete response (indeterminate and incomplete response).

Patients and Methods:

One hundred patients with DTC underwent near-total thyroidectomy and radioactive remnant ablation by iodine-131 (I¹³¹) with regular follow-up every 6 months during the first 2 years and at 6–12-month intervals thereafter by I¹³¹ whole-body scan (WBS), neck ultrasound, and sTg measurement in the hypothyroid state (TSH >30 mU/L). Patients were divided according to the imaging findings and sTg level into three groups: excellent response (ER) – no evidence of disease by imaging and sTg <1 ng/mL, indeterminate or acceptable response (AR) – nonspecific findings on imaging studies and sTg < 10 ng/mL, and incomplete response (IR) – patients with incomplete structural and/or incomplete biochemical response (sTg > 10 ng/mL).

Results:

The follow-up at 6-month postablation showed ER in 3 (3%) patients, AR in 29 (29%) patients, and IR in 68 (68%) patients. The second follow-up at 9–12-month postablation showed dramatic biochemical response with ER, indeterminate, and IR in 50 (50%), 34 (34%), and 16 (16%) patients, respectively, and 14 (14%) patient had structural recurrence. This change is highly statistically significant (P = 0.00). In the last follow-up (ranges from 3 to 10 years), 53 (55.8%) patients achieved ER, 42 (44.2%) AR and no patient with non complete response. The change in patients with IR between the second and the last follow-up is also statistically significant (P = 0.001).

Conclusion:

sTg measurement by the end of the 1^st year is more reliable in the follow-up of patients with DTC and biochemical non complete response and considered significant predictor of disease-free status. Patients with biochemical IR still have the chance to achieve ER or AR by the passage of time without additional therapies.

Papillary thyroid carcinomas with biochemical incomplete or indeterminate responses to initial treatment: repeat stimulated thyroglobulin assay to identify disease-free patients

Papillary thyroid cancer (PTC) patients treated with thyroidectomy and radioiodine remnant ablation (RRA) often have detectable TSH-stimulated thyroglobulin (Tg) levels without localizable disease after primary treatment. To assess the value of repeat stimulated Tg assays in these patients' follow-up, we retrospectively analyzed 86 cases followed in 5 Italian thyroid-cancer referral centers. We enrolled 86 patients with PTCs treated with total/near-total thyroidectomy plus RRA between January 1,1990 and January 31, 2006. In all cases, the initial postoperative visit revealed stimulated serum Tg ≥1 ng/mL, negative Tg antibodies, and no structural evidence of disease. None received empiric radioiodine therapy. Follow-up (median: 9.6 years) included neck ultrasound and basal Tg assays (yearly) and at least 1 repeat stimulated Tg assay. Of the 86 patients analyzed (initial risk: low 63 %, intermediate 35 %, high 2 %), one (1 %) had ultrasound-detected lymph node disease and persistently elevated stimulated Tg levels at 3 years. In 17 (20 %), imaging findings were consistently negative, but the final stimulated Tg levels was still >1 ng/mL (median 2.07 ng/mL, range 1.02-4.7). The other 68 (80 %) appeared disease-free (persistently negative imaging findings with stimulated Tg levels ≤1 ng/mL). Mean intervals between first and final stimulated Tg assays were similar (5.2 and 4.8 years) in subgroups with versus without Tg normalization. Reclassification as disease-free was significantly more common when initial stimulated Tg levels were indeterminate (<10 ng/mL). In unselected PTC cohorts with incomplete/indeterminate biochemical responses to thyroidectomy and RRA, periodic remeasurement of stimulated Tg allows most patients to be classified as disease-free.

2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent. Since the American Thyroid Association's (ATA's) guidelines for the management of these disorders were revised in 2009, significant scientific advances have occurred in the field. The aim of these guidelines is to inform clinicians, patients, researchers, and health policy makers on published evidence relating to the diagnosis and management of thyroid nodules and differentiated thyroid cancer.

METHODS

The specific clinical questions addressed in these guidelines were based on prior versions of the guidelines, stakeholder input, and input of task force members. Task force panel members were educated on knowledge synthesis methods, including electronic database searching, review and selection of relevant citations, and critical appraisal of selected studies. Published English language articles on adults were eligible for inclusion. The American College of Physicians Guideline Grading System was used for critical appraisal of evidence and grading strength of recommendations for therapeutic interventions. We developed a similarly formatted system to appraise the quality of such studies and resultant recommendations. The guideline panel had complete editorial independence from the ATA. Competing interests of guideline task force members were regularly updated, managed, and communicated to the ATA and task force members.

RESULTS

The revised guidelines for the management of thyroid nodules include recommendations regarding initial evaluation, clinical and ultrasound criteria for fine-needle aspiration biopsy, interpretation of fine-needle aspiration biopsy results, use of molecular markers, and management of benign thyroid nodules. Recommendations regarding the initial management of thyroid cancer include those relating to screening for thyroid cancer, staging and risk assessment, surgical management, radioiodine remnant ablation and therapy, and thyrotropin suppression therapy using levothyroxine. Recommendations related to long-term management of differentiated thyroid cancer include those related to surveillance for recurrent disease using imaging and serum thyroglobulin, thyroid hormone therapy, management of recurrent and metastatic disease, consideration for clinical trials and targeted therapy, as well as directions for future research.

CONCLUSIONS

We have developed evidence-based recommendations to inform clinical decision-making in the management of thyroid nodules and differentiated thyroid cancer. They represent, in our opinion, contemporary optimal care for patients with these disorders.

Association between neck ultrasonographic findings and clinico-pathological features in the follicular variant of papillary thyroid carcinoma

OBJECTIVE

The follicular variant of papillary thyroid carcinoma (FVPTC) has multiple histological subtypes. Clinical outcomes of FVPTC are variable depending on the subtypes. This study evaluated the association of pre-operative ultrasonographic (US) findings and clinico-pathological features of FVPTC.

PATIENTS

This retrospective study enrolled patients with FVPTC (n = 70), size-matched classical variant of papillary thyroid carcinoma (CPTC, n = 328), follicular carcinoma (n = 85) and follicular adenoma (FA, n = 120). We defined the histological subtypes of FVPTC as infiltrative (I-FVPTC; n = 19) or encapsulated (E-FVPTC; n = 51) according to the presence of a fibrous capsule. Pre-operative US was reviewed using a US scoring system and classified into low US score (n = 42) and high US score (n = 28).

RESULTS

The median US score for FVPTC was lower than CPTC (2 vs 7, P < 0·001), but higher than FA (2 vs 0, P < 0·001). The median US score for I-FVPTC was significantly higher than E-FVPTC (4 vs 2, P = 0·009). I-FVPTC was more likely to be diagnosed as a malignancy or suspicious for malignancy on cytology than E-FVPTC (P = 0·002). The cumulative risks of cervical lymph node (LN) or distant metastasis according to tumour size were significantly higher in I-FVPTC than E-FVPTC (all P < 0·001). The cumulative risks for cervical LN metastasis or capsular invasion according to tumour size were significantly higher in FVPTC with high US score than FVPTC with low US score (P = 0·005, P < 0·001, respectively).

CONCLUSIONS

Pre-operative US findings of thyroid nodules were associated with not only histological subtypes, but also the clinical behaviour in FVPTC.

Metformin Is Associated with a Favorable Outcome in Diabetic Patients with Cervical Lymph Node Metastasis of Differentiated Thyroid Cancer

BACKGROUND AND OBJECTIVE

Type 2 diabetes is known to increase the risk and progression of certain types of cancer. Metformin treatment of diabetic patients is reported to have beneficial effects on some cancers. We evaluated the clinical outcome of diabetic patients with differentiated thyroid cancer (DTC) according to metformin treatment.

METHODS

We reviewed 943 patients diagnosed with DTC after total thyroidectomy between 1995 and 2005 in a tertiary hospital. The study involved 60 diabetic patients and 210 control patients matched for age, sex, body mass index (BMI), and tumor size.

RESULTS

There were no differences in the clinicopathological features and disease-free survival (DFS) between diabetic patients and the control group over 8.9 years of follow-up. Of the diabetic patients with DTC, 35 patients (58%) were treated with metformin. There were no differences in age, sex, BMI, tumor size, antidiabetic medication, glycated hemoglobin, or C-peptide levels in metformin and nonmetformin groups. However, cervical lymph node (LN) metastasis was more prevalent in the metformin group than in the nonmetformin group (OR 3.52, p = 0.035). Among diabetic patients with cervical LN metastasis of DTC, the metformin subgroup (17.1 years) was associated with longer DFS than the nonmetformin subgroup (8.6 years) (HR 0.16, p = 0.021); metformin treatment was also associated with longer DFS in this subgroup in multivariate analysis after adjusting age, BMI, duration of diabetes, presence of tumor at resection margin, and serum thyroglobulin level at ablation (HR 0.03, p = 0.035).

CONCLUSIONS

Metformin treatment is associated with low recurrence in diabetic patients with cervical LN metastasis of DTC.

Clinicopathological Significance of Minimal Extrathyroid Extension in Solitary Papillary Thyroid Carcinomas

Background

The definitive diagnosis of minimal extrathyroid extension (ETE) is subjective because a well-defined true capsule is absent in the thyroid gland. We subclassified the extent of minimal ETE and investigated the clinicopathological significance of the presence of minimal ETE in patients with solitary papillary thyroid carcinomas (PTCs) and solitary papillary thyroid microcarcinomas (PTMCs).

Methods

A series of 546 patients with solitary PTCs, including 144 patients with solitary PTMCs, were retrospectively analyzed. Whether the presence of minimal ETE had an effect on recurrence-free survival (RFS) along with other clinicopathological parameters was investigated.

Results

The only independent prognostic factor found to be associated with recurrence was the presence of LN metastasis in solitary PTC (p = 0.002) but not in solitary PTMC groups (p = 0.073). The presence of minimal ETE had no effect on RFS in both solitary PTC (p = 0.053) and solitary PTMC (p = 0.816).

Conclusions

The presence of minimal ETE has no significant influence on RFS in solitary PTC and PTMC. There is a risk of overrepresenting the T3 category in solitary PTC and PTMC patients with minimal ETE.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-015-4659-0) contains supplementary material, which is available to authorized users.

Superiority of delayed risk stratification in differentiated thyroid cancer after total thyroidectomy and radioactive iodine ablation

AIM

The aim of this study was to validate the effectiveness of delayed risk stratification (DRS) in predicting structural progression and compare the predictive value of American Thyroid Association (ATA) risk stratification with that of DRS in patients with differentiated thyroid cancer (DTC).

METHODS

A total of 398 patients with DTC who underwent surgery followed by radioactive iodine ablation were enrolled. Patients were categorized as having excellent response, acceptable response, biochemical incomplete response, or structural incomplete response at 8-15 months' evaluation after radioactive iodine ablation for DRS. Effectiveness of DRS was evaluated according to structural progression-free survival (PFS; median follow-up, 10.7 years).

RESULTS

A total of 229 patients (57.5%) were classified as having excellent response, 78 (19.6%) as having acceptable response, 62 (15.6%) as having biochemical incomplete response, and 29 patients (7.3%) as having structural incomplete response. After DRS, 60.2% of intermediate-risk patients and 20.5% of high-risk patients were shifted to the excellent response category. Sixty-nine patients (17.3%) showed structural progression. DRS showed statistical difference in PFS (hazard ratio, 4.268; 95% confidence interval, 3.258-5.477; P<0.001). In multivariate analysis of ATA risk stratification and DRS, DRS was significantly associated with PFS (hazard ratio, 4.383; 95% confidence interval, 3.250-5.912; P<0.001), but ATA risk stratification was not. There was no significant difference in deviances between the use of DRS alone and the use of both DRS and ATA risk stratification (χ=0.103, d.f.=1, P=0.748).

CONCLUSION

DRS is superior to ATA risk stratification in predicting structural disease progression for DTC patients.

A closer look at papillary thyroid carcinoma

Recent surge of thyroid cancer, especially papillary thyroid carcinoma (PTC), ignited a debate on over-diagnosis of cancer. Such increase in incidence is a worldwide phenomenon, but it has been the most prominent in Korea. Although increased detection might have played a major role, some evidences suggest that true increase in incidence have also contributed to such phenomenon. PTC is a very common disease being the most common cancer in human. As the mortality due to PTC is relatively low, understanding pathophysiology of the disease and risk prediction in individual patient have particular importance for optimal management, but little has been known. I suggest a reason for such a commonality of PTC, and would like to describe my view on some aspects of PTC including unresolved issue on management based on our recent observations.

Identification of Intermediate- to High-Risk Papillary Thyroid Carcinoma Patients Who May Be Safely Managed without the Performance of Delayed Stimulated Thyroglobulin Measurements following Total Thyroidectomy and Radioactive Iodine Therapy

Background. The measurement of stimulated thyroglobulin (sTg) after total thyroidectomy and remnant radioactive iodine (RAI) ablation is the gold standard for monitoring disease status in patients with papillary thyroid carcinomas (PTCs). The aim of this study was to determine whether sTg measurement during follow-up can be avoided in intermediate- and high-risk PTC patients. Methods. A total of 346 patients with PTCs with an intermediate or high risk of recurrence were analysed. All of the patients underwent total thyroidectomy as well as remnant RAI ablation and sTg measurements. Preoperative and postoperative parameters were included in the analysis. Results. Among the preoperative parameters, age below 45 years and preoperative Tg above 19.4 ng/mL were significant risk factors for predicting detectable sTg during follow-up. Among the postoperative parameters, thyroid capsular invasion, lymph node metastasis, and ablative Tg above 2.9 ng/mL were independently correlated with a detectable sTg range. The combination of ablative Tg less than 2.9 ng/mL with pre- and postoperative independent risk factors for detectable sTg increased the negative predictive value for detectable sTg up to 98.5%. Conclusions. Based on pre- and postoperative parameters, a substantial proportion of patients with PTCs in the intermediate- and high-risk classes could avoid aggressive follow-up measures.

Biomarkers for anti-angiogenic therapy in cancer

Angiogenesis, the development of new vessels from existing vasculature, plays a central role in tumor growth, survival, and progression. On the molecular level it is controlled by a number of pro- and anti-angiogenic cytokines, among which the vascular endothelial growth factors (VEGFs), together with their related VEGF-receptors, have an exceptional position. Therefore, the blockade of VEGF signaling in order to inhibit angiogenesis was deemed an attractive approach for cancer therapy and drugs interfering with the VEGF-ligands, the VEGF receptors, and the intracellular VEGF-mediated signal transduction were developed. Although promising in pre-clinical trials, VEGF-inhibition proved to be problematic in the clinical context. One major drawback was the generally high variability in patient response to anti-angiogenic drugs and the rapid development of therapy resistance, so that, in total, only moderate effects on progression-free and overall survival were observed. Biomarkers predicting the response to VEGF-inhibition might attenuate this problem and help to further individualize drug and dosage determination. Although up to now no definitive biomarker has been identified for this purpose, several candidates are currently under investigation. This review aims to give an overview of the recent developments in this field, focusing on the most prevalent tumor species.