Dynamic risk stratification for medullary thyroid cancer according to the response to initial therapy

Fundamentals and Recent Advances in the Evaluation and Management of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare primary neuroendocrine thyroid carcinoma that is distinct from other thyroid or neuroendocrine cancers. Most cases of MTC are sporadic, although MTC exhibits a high degree of heritability as part of the multiple endocrine neoplasia syndromes. REarranged during Transfection (RET) mutations are the primary oncogenic drivers and advances in molecular profiling have revealed that MTC is enriched in druggable alterations. Surgery at an early stage is the only chance for cure, but many patients present with or develop metastases. C-cell-specific calcitonin trajectory and structural doubling times are critical biomarkers to inform prognosis, extent of surgery, likelihood of residual disease, and need for additional therapy. Recent advances in the role of active surveillance, regionally directed therapies for localized disease, and systemic therapy with multi-kinase and RET-specific inhibitors for progressive/metastatic disease have significantly improved outcomes for patients with MTC.

Serum Biochemical Markers for Medullary Thyroid Carcinoma: An Update

Introduction

Medullary thyroid carcinoma (MTC), a rare malignancy, requires early diagnosis for optimal patient outcomes. An important aspect of MTC diagnosis is the assessment of serum biomarkers. This review aimed to evaluate the use of serum biomarkers in the diagnosis, prognosis, and follow-up of MTC.

Methods

A thorough search of PubMed covering 1975 to 2022 was conducted to identify English-language articles on MTC serum biomarkers.

Results

The review revealed that calcitonin (Ctn) and carcinoembryonic antigen (CEA) remain the most important serum biomarkers for MTC diagnosis and management. Despite limited studies on procalcitonin (PCT), its stability and ability to exclude interference from inflammation make it a valuable potential marker of MTC. Although the positive rate of serum CA19-9 levels in MTC patients was not high, it can be used as an indicator of poor prognosis in advanced MTC. Other serum markers, including chromogranin A, gastrin-releasing peptide precursor, and neurospecific enolase, did not show any unique value in MTC diagnosis and management.

Conclusion

Taken together, this review emphasized the importance of serum biomarkers, particularly Ctn and CEA, in the diagnosis and management of MTC. PCT shows promise as a valuable potential marker, whereas CA19-9 can be used as a prognostic indicator of advanced MTC. Further research is needed to validate the significance of these serum biomarkers in MTC and determine the effects of confounding factors on their levels. Clinicians should consider using these markers in MTC diagnosis, prognosis, and follow-up, particularly for patients with advanced disease.

Clinical evolution of sporadic medullary thyroid carcinoma with biochemical incomplete response after initial treatment

CONTEXT

The clinical response after surgery is a determinant in the management of patients with medullary thyroid carcinoma (MTC). In case of excellent or structural incomplete response, the follow-up strategies are well designed. Conversely, in case of biochemical incomplete response (BiR) the management is not clearly defined.

PURPOSE

To evaluate the overall and per-site prevalence of structural disease detection in sporadic MTC patients with BiR and to assess the predictive value of various clinical, biochemical, and genetics features.

METHODS

We evaluated data of 599 consecutive patients surgically treated for sporadic MTC (2000-2018) and followed-up at Endocrine Unit of the University Hospital of Pisa.

RESULTS

After a median of 5 months from surgery, 145/599 (24.2%) patients were classified as BiR. Structural disease was detected in 64/145 (44.1%), after a median time of 3.3 years. In 73.6% structural disease was detected at a single site, prevalently cervical lymph nodes. Among several others, at the time of first evaluation after surgery, only basal calcitonin (bCTN) and stage IVa/b were independent predictive factors. Also, structural disease was more frequent in patients with shorter CTN doubling time and somatic RET mutation.

CONCLUSIONS

In sporadic MTC patients with BiR the risk of detection of structural disease was about 50% at 10 years. Higher bCTN levels and staging predicted the risk of detecting structural disease. According to these findings, a stricter follow-up should be reserved to MTC with BiR and elevated values of bCTN and to those with an advanced stage. Long follow-up should anyway be considered for all BiR patients since 50% of them develop structural disease within 10 years.

An Undetectable Postoperative Calcitonin Level Is Associated with Long-Term Disease-Free Survival in Medullary Thyroid Carcinoma: Results of a Retrospective Cohort Study

Background: Calcitonin measurement is widely used in the diagnosis, prognosis, and follow-up of patients with medullary thyroid carcinoma (MTC). The prognostic value of undetectable postoperative calcitonin (POCal) in long-term disease outcomes remains uncertain. Objective: The aim of this study is to evaluate POCal as a prognostic marker for long-term MTC disease status. Methods: A retrospective cohort study was carried out. We collected data from the medical records of patients with MTC attending two tertiary teaching hospitals. Patients were divided according to POCal into two groups: undetectable (below the detection limit) or detectable. The outcome was determined at the last medical visit and defined as disease free (undetectable calcitonin and no evidence of disease on imaging), persistent disease (detectable calcitonin with or without structural disease), or disease-related death. Results: Three hundred thirty-four MTC patients were included in the study. The mean age at diagnosis was 41.1 ± 18.6 years; 202 patients (60.5%) were women; and 167 patients (50.0%) had sporadic MTC. The median tumor size was 2.0 cm (1.1-3.5 cm); 164 patients (49.1%) had lymph node metastasis and 63 patients (18.9%) had distant metastasis. At the first postoperative evaluation (3-6 months after surgery), 141 patients had undetectable POCal (mean age = 37.9 years, 70.9% women, median tumor size 1.5 cm [0.7-2.5 cm]; 28 [19.9%] had lymph node metastasis and none had distant metastasis). After a median follow-up of 7.7 years (2.1-13.2 years), 127 (90.1%) of these patients were free of disease, whereas 14 (9.9%) had persistent biochemical disease with stable calcitonin levels. No patient with undetectable POCal died of the disease. In the detectable POCal group (mean age = 42.9 years, 52.8% women, median tumor size 3.0 cm [1.8-4.2 cm]; 136 [70.5%] had lymph node metastasis and 63 [32.6%] had distant metastasis), 18 (9.2%) patients achieved disease-free status, 51 (26.6%) had biochemical disease, and 61 (31.6%) had persistent structural disease. Sixty-three (32.6%) patients died of disease-related events. Further analysis using a multivariate model identified undetectable POCal as an independent prognostic variable for disease-free status (HR = 5.33, CI = 2.86-9.94; p < 0.001). Conclusions: POCal is a strong prognostic marker for long-term disease-free survival and might help define follow-up strategies for MTC patients.

Tumor Grade Predicts for Calcitonin Doubling Times and Disease-Specific Outcomes After Resection of Medullary Thyroid Carcinoma

Background: Tumor grade is a new validated prognostic factor for medullary thyroid cancer (MTC). Calcitonin doubling time can predict MTC recurrence. We aimed to describe the association of tumor grade with calcitonin doubling and its effect on disease-specific outcomes times after resection. Methods: A retrospective analysis of MTC patients who underwent resection at a single tertiary-care cancer center between 1986 and 2017 were evaluated. Tumors were designated as high-grade MTC if two head and neck pathologists identified mitotic index ≥5 per 2 mm2, tumor necrosis, or a Ki67 proliferative index ≥5% within the tumor. Calcitonin doubling time was calculated using a validated calculator with at least three consecutive levels. Using Cox proportional hazards models, outcomes evaluated included locoregional relapse-free survival (LRFS), distant metastasis-free survival (DMFS), and overall survival (OS). Results: Among 117 patients, 95 were low grade and 22 high grade. Median follow-up was 70.2 months. High-grade patients demonstrated significantly faster calcitonin doubling times when compared with low-grade patients (8.51 ± 3.22 months vs. 38.42 ± 11.19 months; p < 0.001). In addition, most high-grade patients (66.7%) had calcitonin doubling times less than 1 year compared with fewer low-grade patients (1.0%; p < 0.001). High- and low-grade patients were further stratified by those who had calcitonin doubling times less than or greater than 2 years-a previously validated prognostic cutoff point. For patients with calcitonin doubling times less than 2 years, 70% were high grade, while 30% were low grade (p < 0.001). On multivariate analysis comparing grade and calcitonin doubling times, high-grade patients had significantly worse LRFS (hazards ratio [HR] 4.77 [confidence interval; CI 1.19-8.81]), DMFS (HR 7.25 [CI 2.36-22.28]), and OS (HR 6.04 [CI 1.85-19.72]; p < 0.05 for all), while calcitonin doubling times less than 2 years had worse DMFS (HR 7.22 [CI 1.05-49.75]). High-grade patients with calcitonin doubling times less than 2 years had associated worse LRFS and OS (both p < 0.05) compared with low-grade patients. Conclusions: The majority of high-grade MTC patients have calcitonin doubling times less than 2years. Close monitoring should be advocated for patients assessed to have high-grade tumors as they are at risk for poor disease-specific outcomes and structural recurrence.

Prognostic value of LODDS in medullary thyroid carcinoma based on competing risk model and propensity score matching analysis

Log odds of positive lymph nodes (LODDS) is an independent prognostic factor for patients with medullary thyroid carcinoma (MTC). However, the optimal cutoff value for LODDS needs to be further confirmed, and previous studies have ignored the prevalent competing events of non-cancer deaths among patients with MTC, thus possibly overestimating the risk of death from cancer. The information of patients with MTC who underwent total thyroidectomy was collected from SEER database. Restricted cubic splines (RCS) were used to determine the optimal cutoff for LODDS. Moreover, patients' overall survival (OS) and disease-specific survival (DSS) were determined using Kaplan-Meier and Cox proportional-hazards model. The competing risk models (CRM) were used to reduce the effect of competing events, and propensity score matching was performed to balance the confounding factors between groups. The cutoff value of LODDS determined by RCS was - 1.004, and a total of 2314 patients with MTC were recruited. In the CRM after PSM, factors such as age over 55 years at diagnosis, being male, treatment with chemotherapy or radiotherapy, unknown tumor size, and LODDS > - 1.004 were significantly associated with poor prognosis of patients both in univariate and multivariate analyses, while the presence of multifocal tumor indicated better prognosis. Patients with MTC who were over 55 years old at diagnosis, were male, received chemotherapy or radiation, had an unclear initial tumor size, and had LODDS > - 1.004 had a worse prognosis than patients with multifocal tumor.

Novel Therapeutics and Treatment Strategies for Medullary Thyroid Cancer

Medullary thyroid cancer is a rare thyroid malignancy with unique management considerations. In general, small intrathyroidal tumors are cured by total thyroidectomy with central compartment dissection, while large tumors and those with disease spread to regional lymph nodes and distant organs (most commonly lung, liver, and bone) are more difficult to cure. The last decade has seen significant progress in the treatment of advanced MTC, largely due to the discovery and availability of novel targeted therapies, including new drugs specifically targeting the RET protooncogone.

Early postoperative calcitonin-to-preoperative calcitonin ratio as a predictive marker for structural recurrence in sporadic medullary thyroid cancer: A retrospective study

BACKGROUND

Calcitonin (Ctn) is widely used as a marker in the diagnosis, prognosis, and postoperative follow-up of patients with medullary thyroid carcinoma (MTC). The prognostic value of postoperative calcitonin-to-preoperative calcitonin ratio (CR), reflecting the change in Ctn level of response to initial treatment, remains uncertain in long-term disease outcomes. This study aims to determine the cut-off value of CR for predicting structural recurrence and assess the prognostic role of CR in patients with MTC.

METHODS

We retrospectively reviewed patients with MTC in Sun Yat-sen University Cancer Center (SYSUCC) between 2000 and 2022. CR is defined as the ratio of postoperative Ctn level on the day of discharge divided by preoperative Ctn level. In order to determine the optimal cut-off value of CR, the receiver operating characteristic (ROC) analysis was performed. We evaluate the effect of CR on recurrence-free survival (RFS) by using the Kaplan-Meier method and Cox regression analysis. Then, a nomogram based on CR was constructed.

RESULTS

In total, 112 sporadic MTC patients were included in this study. The optimal cut-off value of CR that predicted disease recurrence was 0.125. Patients with CR≥0.125 showed significantly worse RFS than patients with CR <0.125, respectively (3-years RFS rate of 63.1 vs. 94.7%, 5-years RFS rate of 50.7 vs. 90.3%, P < 0.001). In the multivariate analysis, CR was the strongest independent predictor of structural recurrence (HR: 5.050, 95% CI: 2.247-11.349, P <0.001). Tumor size (HR: 1.321, 95% CI: 1.010-1.726, P =0.042), multifocality (HR: 2.258, 95% CI: 1.008-5.058, P =0.048) and metastasized lymph nodes (HR: 3.793, 95% CI: 1.617-8.897, P <0.001) were also independent predictors of structural recurrence. The uncorrected concordance index (c-index) of the nomogram was 0.827 (95% CI, 0.729-0.925) for RFS, and bias-corrected c-index were similar. As compared to TNM stage, the nomogram based on CR provided better discrimination accuracy.

CONCLUSIONS

We demonstrate that CR is a strong prognostic marker to predict structural recurrence in patients with sporadic MTC. The nomogram incorporating CR provided useful prediction of RFS for patients with sporadic MTC to provide personalized treatment.

[Medullary thyroid carcinoma: current clinical progress]

Medullary thyroid cancer (MTC) is infrequently found among all thyroid nodules in previously iodine deficient regions. Measurement of serum calcitonin is an important tool for early identification of MTC among the large number of thyroid nodules. With the use of modern laboratory assays and sex-specific reference intervals, clinical diagnostic specificity has considerably improved. While the prognosis of MTC confined to the thyroid (stage I/II tumors) is favorable with a disease specific survival similar to the general population, biochemical cure rates by surgery decreases in extensive disease. Few patients present with aggressive tumours that show rapid progression or advanced disease at diagnosis. Oncogenic mutations in the RET protooncogene occur in ~25 % of patients as part of the multiple endocrine neoplasia type 2 syndromes and are present as somatic mutations in 60 % of all MTC and up to 90 % of metastatic cases.The multi-tyrosine kinase inhibitors vandetanib and cabozantinib have been approved for progressive advanced disease but have low specificity for the RET tyrosine kinase. With the advent of highly selective RET inhibitors selpercatinib and pralsetinib, the treatment landscape has profoundly changed. Selpercatinib is approved in the EU for treatment in the second and later lines of treatment. They have demonstrated a favorable safety profile and high objective response rates also in previously treated MTC patients. The use of selective RET inhibitors in the first line setting is currently the subject of clinical trials.

Current Guidelines for Management of Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor originating from the parafollicular cells. The diagnostic and therapeutic strategies for the condition are different from those used for well-differentiated thyroid cancer. Since the 2015 American Thyroid Association guidelines for the diagnosis and treatment of MTC, the latest, including the National Comprehensive Cancer Network and European Association for Medical Oncology guidelines have been updated to reflect several recent advances in the management of MTC. Advances in molecular diagnosis and postoperative risk stratification systems have led to individualized treatment and follow-up strategies. Multi-kinase inhibitors, such as vandetanib and cabozantinib, can prolong disease progression-free survival with favorable adverse effects. In addition, potent selective rearranged during transfection (RET) inhibitors (selpercatinib and pralsetinib) have shown a promising efficacy in recent clinical trials. This review summarizes the management of MTC in recent guidelines focused on sporadic MTC.

Predicting Outcomes in Sporadic and Hereditary Medullary Thyroid Carcinoma over Two Decades

Background: Medullary thyroid cancer (MTC) can be associated with significant morbidity and mortality in advanced cases. Hence, we aimed to identify factors at the time of MTC surgery that predict overall survival (OS), disease-specific survival (DSS), locoregional recurrence/persistence (LR), and distant metastases (DM). Methods: We performed a retrospective study of clinicopathologic, radiological, and laboratory data in MTC patients who underwent thyroidectomy at Mayo Clinic from January 1995 to December 2015. Results: We identified 163 patients (mean age 48.4 years, 48% males), 102 with sporadic MTC and 61 with hereditary disease (n = 46 multiple endocrine neoplasia [MEN] 2A, n = 3 MEN 2B, n = 12 familial MTC) with a median follow-up time of 5.5 years. On univariate analysis, age >55 years, male sex, DM at the time of surgery (M1), lateral neck lymph node (LN) involvement (N1b), gross extrathyroidal extension (ETE), American Joint Committee on Cancer (AJCC) stage 3/4, tumor size (T) 3/4, tumor size, and postoperative calcitonin (Ctn) and carcinoembryonic antigen (CEA) were significant predictors of worse OS and DSS. On multivariable analysis, both gross ETE (hazard ratio [HR] 4.62, 6.58) and M1 (HR 5.11, 10.45) remained significant predictors of worse OS as well as DSS, while age >55 years (HR 3.21), male sex (HR 2.42), and postoperative Ctn (HR 1.002 for every 100 pg/mL increase) were significant only for worse OS. On univariate analysis, male sex, M1, N1b, gross ETE, stage 3/4, T 3/4, tumor size, number of LNs involved, and postoperative Ctn were significant predictors of LR and DM; age >55 years was additionally significant for DM. On multivariable analysis, gross ETE (HR 3.16, 5.93) and N1b (HR 4.31, 4.64) remained significant predictors of LR and DM; ratio of resected/involved LN (HR 10.91) was additionally predictive for LR and postoperative Ctn (HR 1.003 for every 100 pg/mL increase) for DM. Conclusions: Disease burden at initial surgery, especially gross ETE, lateral neck LN involvement, and DM, as well as the biochemical response to surgery appear to be more important than demographic factors in terms of MTC prognosis. These findings highlight the importance of rigorous perioperative assessment to better predict MTC outcomes.

Comparison Between Familial and Sporadic Non-medullary Thyroid Carcinoma: A Retrospective Individual Risk Factor-Matched Cohort Study

BACKGROUND

This study aimed to compare clinicopathologic features and outcomes between patients with familial non-medullary thyroid carcinoma (FNMTC) and patients with sporadic non-medullary thyroid carcinoma (SNMTC) after performing individual risk factor-matching. Additionally, the study evaluated a dynamic risk stratification (DRS) system to validate its usefulness for familial-type thyroid carcinoma.

METHODS

After individual risk factor-matching, 286 patients remained in the FNMTC group, and 858 patients were assigned to the SNMTC group consisting of papillary thyroid carcinoma (PTC). The prognostic outcomes were compared between the two groups in a matched cohort.

RESULTS

During the mean follow-up period of 142 months, recurrences were experienced by 64 patients in the sporadic group (7.5%) and 29 patients in the familial group (10.1%). In the multivariate analysis, the independent risk factors for recurrence were primary tumor size (p = 0.033), gross extrathyroidal extension (p = 0.001), and lymph node metastasis (p < 0.001). The independent risk factors did not include family history alone (p = 1.101) or the number of affected family members (p = 0.122 for 2 members and p = 0.625 for ≥ 3 members). In this matched-cohort study, the DRS system was well adjusted in the FNMTC and SNMTC groups. Moreover, the proportion of DRS categories and the recurrence rate in each DRS category were similar between the familial and sporadic groups.

CONCLUSIONS

Family history did not present a statistically significant association with a poor prognosis for PTC patients. With a family history of PTC alone, less aggressive treatment could be considered. In this matched cohort, DRS was adjusted well and could be useful in predicting prognosis, even for PTC patients with a family history of PTC.

Long-Term Outcomes and Aggressiveness of Hereditary Medullary Thyroid Carcinoma: 40 Years of Experience at One Center

CONTEXT

Recent data on long-term outcomes and aggressiveness of medullary thyroid carcinoma (MTC) are lacking for patients with multiple endocrine neoplasia type 2 (MEN2).

OBJECTIVES

To analyze the long-term outcomes in MEN2 and compare MTC aggressiveness in three defined RET mutation-risk categories: moderate risk (MOD), high risk (H), and highest risk (HST).

DESIGN, SETTING

Retrospective study of 263 operated patients with MEN2 from one German tertiary referral center from 1979 to 2017 comparing demographic, biochemical, genetic, and outcome parameters.

INTERVENTION

None (observational study).

MAIN OUTCOME MEASURE

Long-term survival and outcomes in three risk groups.

RESULTS

Surgery was performed at a mean age of 35.3 ± 18.8 (MOD, n = 122), 23.0 ± 15.7 years (H, n = 120), and 14.9 ± 9.3 (HST, n = 21) years (P < 0.05). The mean follow-up was 12.9 ± 9.8 years. Age and tumor stage at diagnosis differed among the three risk groups (P < 0.0001). Multivariate analysis of disease-specific survival (DSS) showed that increasing age [hazard ratio (HR), 1.06; 95% CI, 1.02 to 1.09], stage III/IV at diagnosis (HR, 7.39; 95% CI, 2.39 to 22.8), and HST group (HR, 14.4; 95% CI, 3.32 to 62.6) were significantly associated with worse DSS; the H group was not (P = 0.175). The DSS rates and outcomes were not different between the MOD and H groups (P = 0.179 and P = 0.893, respectively) but were significantly inferior in the HST group (P < 0.0008 and P < 0.0001, respectively).

CONCLUSION

MTC in patients with MEN2 showed a clearly different age of onset in the different risk groups. DSS and outcomes after MTC diagnosis were similar in the MOD and H groups, suggesting similar tumor behavior. The HST group had inferior outcomes and survival vs the MOD and or H groups.

Clinico-pathologic and dynamic prognostic factors in sporadic and familial medullary thyroid carcinoma: an Israeli multi-center study

OBJECTIVE

Multiple clinical, pathological and biochemical variables, including the response to initial treatment, are associated with medullary thyroid carcinoma (MTC) prognosis. Studies that include separate analyses of familial and sporadic MTC patients followed for long period are scarce. This study evaluated the association between baseline clinico-pathologic variables and response to initial treatment and short- and long-term disease outcomes in sporadic and familial MTC.

METHODS

Patients treated for MTC at four tertiary medical centers were retrospectively analyzed. Clinical and pathological data were collected. The outcomes measured included disease persistence 1 year after diagnosis, disease persistence at last follow-up, disease-related mortality (DRM) and all-cause mortality.

RESULTS

The study enrolled 193 patients (mean age: 48.9 ± 18.7, 44.7% males), of whom 18.1% were familial cases. The mean follow-up period was 10.1 ± 9.4 years (8.5 ± 8.1 in sporadic and 16.9 ± 11.6 in familial MTC). Disease persistence 1-year after diagnosis and at last follow-up was detected in 56.1 and 60.4% patients, respectively. All-cause and DRM were 28.5 and 12.6%, respectively. Extra-thyroidal extension (ETE) and distant metastases (DM) were associated with disease persistence at last follow-up. ETE and DM were also significantly associated with DRM. Complete remission 1 year after diagnosis had high correlation with no evidence of disease at last follow-up (Cramer's V measure of association 0.884, P < 0.001) and with 100% disease-specific survival (Cramer's V measure of association 0.38, P < 0.001).

CONCLUSIONS

Apart from clinico-pathologic parameters, close correlation was found between 1-year status and long-term prognosis. These results underscore the importance of combining classical and dynamic factors for both sporadic and familial MTC prognostication and treatment decision making.

Survival and Long-Term Biochemical Cure in Medullary Thyroid Carcinoma in Denmark 1997-2014: A Nationwide Study

BACKGROUND

Survival of medullary thyroid carcinoma (MTC) subgroups in relation to the general population is poorly described. Data on the factors predicting long-term biochemical cure in MTC patients are nonexistent at a population level. A nationwide retrospective cohort study of MTC in Denmark from 1997 to 2014 was conducted, aiming to detect subgroups with survival similar to that of the general population and to identify prognostic factors for disease-specific survival and long-term biochemical cure.

METHODS

The study included 220 patients identified from the nationwide Danish MTC cohort between 1997 and 2014. As a representative sample of the general population, a reference population matched 50:1 to the MTC cohort was used.

RESULTS

Patients diagnosed with hereditary MTC by screening (hazard ratio [HR] = 1.5 [confidence interval (CI) 0.5-4.3]), patients without regional metastases (HR = 1.4 [CI 0.9-2.3]), and patients with stage I (HR = 1.3 [CI 0.6-3.1]), stage II (HR = 1.1 [CI 0.6-2.3]), and III (HR = 1.3 [CI 0.4-4.2]) disease had an overall survival similar to the reference population. On multivariate analysis, the presence of distant metastases (HR = 12.3 [CI 6.0-25.0]) predicted worse disease-specific survival, while the absence of regional lymph node metastases (odds ratio = 40.1 [CI 12.0-133.7]) was the only independent prognostic factor for long-term biochemical cure.

CONCLUSIONS

Patients with hereditary MTC diagnosed by screening, patients without regional metastases, and patients with stages I, II, and III disease may have similar survival as the general population. The presence of distant metastases predicted worse disease-specific survival, while the absence of regional metastases predicted long-term biochemical cure.

Completeness of RET testing in patients with medullary thyroid carcinoma in Denmark 1997-2013: a nationwide study

Background

The completeness of REarranged during Transfection (RET) testing in patients with medullary thyroid carcinoma (MTC) was recently reported as 60%. However, the completeness on a population level is unknown. Similarly, it is unknown if the first Danish guidelines from 2002, recommending RET testing in all MTC patients, improved completeness in Denmark. We conducted a nationwide retrospective cohort study aiming to evaluate the completeness of RET testing in the Danish MTC cohort. Additionally, we aimed to assess the completeness before and after publication of the first Danish guidelines and characterize MTC patients who had not been tested.

Methods

The study included 200 patients identified from the nationwide Danish MTC cohort 1997–2013. To identify RET tested MTC patients before December 31, 2014, the MTC cohort was cross-checked with the nationwide Danish RET cohort 1994–2014. To characterize MTC patients who had not been RET tested, we reviewed their medical records and compared them with MTC patients who had been tested.

Results

Completeness of RET testing in the overall MTC cohort was 87% (95% CI: 0.81–0.91; 173/200). In the adjusted MTC cohort, after excluding patients diagnosed with hereditary MTC by screening, completeness was 83% (95% CI: 0.76–0.88; 131/158). Completeness was 88% (95% CI: 0.75–0.95; 42/48) and 81% (95% CI: 0.72–0.88) (89/110) before and after publication of the first Danish guidelines, respectively. Patients not RET tested had a higher median age at diagnosis compared to those RET tested. Median time to death was shorter in those not tested relative to those tested.

Conclusion

The completeness of RET testing in MTC patients in Denmark seems to be higher than reported in other cohorts. No improvement in completeness was detected after publication of the first Danish guidelines. In addition, data indicate that advanced age and low life expectancy at MTC diagnosis may serve as prognostic indicators to identify patients having a higher likelihood of missing the compulsory RET test.

Dynamic risk stratification in papillary thyroid carcinoma measuring 1 to 4 cm

BACKGROUND AND OBJECTIVES

This study aimed to validate the dynamic risk stratification (DRS) system, evaluate its correlation with structural recurrence, and assess the clinicopathological risk factors associated with a nonexcellent response to initial therapy in patients with papillary thyroid cancer (PTC) measuring 1 to 4 cm.

METHODS

A total of 762 patients with classic PTC measuring 1 to 4 cm were classified into four categories based on their response to initial therapy 2 years postoperatively.

RESULTS

Structural recurrent disease occurred in 4.7%, 17.1%, 48.4%, and 83.9% of patients with excellent, indeterminate, biochemically incomplete, and structurally incomplete responses, respectively, at the time of the last follow-up. The response to initial therapy in the DRS was one of the independent risk factors for structural recurrence. The disease-free survival curves of patients with different responses showed significant differences (P < 0.001). Extensive extrathyroidal extension, lymph node (LN) metastasis, number of metastatic LNs greater than 2.0, metastatic LN ratio greater than 0.22, and extranodal extension were independent risk factors for nonexcellent response to initial therapy.

CONCLUSIONS

DRS can be a useful tool in predicting structural recurrence and guiding postoperative management and follow-up strategies in patients with PTC measuring 1 to 4 cm.

Preoperative Clinical and Sonographic Predictors for Lateral Cervical Lymph Node Metastases in Sporadic Medullary Thyroid Carcinoma

BACKGROUND

Total thyroidectomy and cervical lymph node (LN) dissection is generally recommended in patients with medullary thyroid carcinoma (MTC). However, there is no clear evidence for whom to perform prophylactic lateral neck dissection in MTC patients without evident lateral cervical lymph node (LCLN) metastasis in preoperative images. This study evaluated the preoperative features for predicting the LCLN metastasis of MTC.

METHODS

The study included 26 MTC patients with LCLN metastasis at initial surgery (N1b group) and 47 MTC patients without any LN metastasis or recurrence of disease (N0-NED group). The association between LCLN metastasis and preoperative clinical and sonographic characteristics (size, location, solid component, shape, margin, echogenicity, calcification, and subcapsular location of the tumor) were evaluated.

RESULTS

There were no significant differences in age and sex between the N1b and N0-NED groups. Preoperative serum levels of calcitonin >65 pg/mL were associated with LCLN metastasis (p < 0.001). In preoperative neck ultrasonography (US), patients in the N1b group were more commonly found with a larger tumor (>1.5 cm) of irregular shape with a spiculated margin and a subcapsular location than those in the N0-NED group (p = 0.029, p < 0.001, p < 0.001, and p < 0.001, respectively). Increases in the number of these LCLN metastasis-related features were significantly associated with higher risk for LCLN metastasis (p < 0.001). The presence of two or more predictors was an appropriate cutoff point for predicting LCLN metastasis of MTC with 73.1% sensitivity and 91.5% specificity.

CONCLUSIONS

MTC tumors with high preoperative calcitonin levels (>65 pg/mL), larger size (>1.5 cm), irregular shape, spiculated margins, and subcapsular locations in the neck US are at higher risk for LCLN metastasis. MTC patents with fewer than two predictors might be suitable for treatment without prophylactic LCLN dissection.

Dynamic risk stratification in medullary thyroid carcinoma: Single institution experiences

Recently, dynamic risk stratification has been found to be more valuable than static anatomic staging system in nonmedullary thyroid cancer and this strategy has also been accepted in medullary thyroid cancer (MTC). The present study was designed to compare the clinical usefulness of response to initial therapy stratification with a traditional anatomic staging system.From August 1982 to December 2012, a total of 144 MTC patients underwent thyroidectomy in Yonsei University Hospital. Among them, 117 (82.2%) patients with complete clinical data and sustained follow-up were enrolled in this study. Clinicopathological features and surgical outcomes were analyzed by retrospective medical chart review. Mean follow-up duration was 85.78 ± 62.51 months.In this study, mean tumor size was 1.94 ± 1.40 cm and 22 (18.9%) patients had hereditary MTC; 95 (81.1%) patients had sporadic MTC. Stage I patients had highest probability of excellent response to initial therapy (92.1%). Stage IV patients had highest probability of biochemical and structural incomplete response to initial therapy (57.5% and 30.3%) and lowest probability of excellent response to initial therapy (12.1%). Both response to initial therapy stratification and TNM staging system offered useful prognostic information in this study. The TNM staging system provided risk stratification pertaining to disease-free survival (DFS), disease-specific survival (DSS), and the probability of having no evidence of disease at final outcome, but did not provide risk stratification pertaining to the probability of having biochemical persistent/recurrence disease at final outcome. However, response to initial therapy stratification provided risk stratification pertaining to not only DFS, DSS, and the probability of having no evidence of disease at final outcome but also the probability of having biochemical persistent/recurrence disease at final outcome.In this study, we demonstrated that dynamic risk stratification with adjusted response to initial therapy system can offer more useful prognostic information than anatomic staging system in MTC.

Dynamic risk stratification in the follow-up of thyroid cancer: what is still to be discovered in 2017?

The adequate risk stratification in thyroid carcinoma is crucial to avoid on one hand the overtreatment of low-risk and on the other hand the undertreatment of high-risk patients. The question how to properly assess the risk of relapse has been discussed during recent years and resulted in a substantial change in our approach to risk stratification in differentiated thyroid cancer, proposed by the newest ATA guidelines. First initial risk stratification, based on histopathological data is carried out just after primary surgery. It should be emphasized, that a high quality of histopathological report is crucial for proper risk stratification. Next, during the follow-up, patients are restratified considering their response to treatment applied and classified to one of the following categories: excellent response, biochemical incomplete response, structural incomplete or indeterminate response. This new approach is called dynamic risk stratification as, in contrary to the previous rigid evaluation performed at diagnosis, reflects a real-time prognosis and thereby substantially influences and personalizes disease management. In this review, we raise some unresolved questions, among them the lack of prospective studies, fulfilling evidence-based criteria, necessary to validate this model of risk stratification. We also provided some data concerning the use of dynamic risk stratification in medullary thyroid cancer, not yet reflected in ATA guidelines. In conclusion, dynamic risk stratification allows for better prediction of the risk of recurrence in thyroid carcinoma, what has been demonstrated in numerous retrospective analyses. However, the validation of this approach in prospective studies seems to be our task for near future.

The Management of Medullary Thyroid Carcinoma in the Era of Targeted Therapy

Medullary thyroid cancer (MTC) is a rare cancer comprising approximately 5% of all thyroid cancers. The majority arises sporadically but around 25% are hereditary forming part of the Multiple Endocrine Neoplasia (MEN) type 2 syndromes. The initial management is surgical, the extent of resection determined by radiological stage, presence of and specific REarranged during Transfection (RET) oncogene mutation and level of serum calcitonin. External beam radiotherapy may be utilised in the adjuvant setting to improve local control rates. Conventional cytotoxic agents remain essentially futile in the management of advanced MTC with response rates of around 15-20% at best. Over the last decade, alongside a greater understanding of the molecular pathogenesis of MTC we have seen the development of small molecule agents including tyrosine kinase inhibitors targeting vascular endothelial growth factor receptors (VEGFRs) and RET with activity in advanced MTC. This review will examine the evidence for this therapeutic approach, when to consider initiating and how to manage toxicities arising from such therapies in the treatment of advanced MTC.