Evaluation of a Novel Collagen Hemostatic Matrix: Comparison of Two Hemostatic Matrices in a Rabbits Jejunal Artery Injury Model.

BACKGROUND: We evaluated the hemostatic efficacy and immunogenicity of CollaStat compared with FloSeal in a rabbit jejunal artery injury model. METHODS: A total of 27 experimental rabbits were used in the study. For each hemostatic agent, an injury was created in one of the right angles of the jejunal arteries originating from the vascular arcs. Time to hemostasis was determined after applying manual compression to the wound for 30 s, which was repeated a maximum of three times in cases of persistent bleeding. On postoperative day 7, the concentration of serum antithrombin antibody was measured among agent-treated and nontreated control groups. RESULTS: The mean time to hemostasis for CollaStat was significantly shorter than for FloSeal (64.0 ± 5.0 versus 84.0 ± 7.8 s; P = 0.040). There were no significant differences in rabbit serum mean anti-thrombin Ab concentration between CollaStat-treated, FloSeal -treated, and the control groups (8.43 ± 0.44 versus 8.18 ± 7.8 versus 9.58 ± 1.11 ng/mL; P = 0.065). CONCLUSIONS: According to our study, CollaStat was more efficient in achieving hemostasis in a rabbit jejunal artery injury and exhibited nonsignificant immunogenicity compared with FloSeal. These findings suggest that CollaStat has acceptable hemostatic potential for controlling significant arterial bleeding.

Posterior Retroperitoneoscopic Resection of Extra-adrenal Paraganglioma Located in the Aorto-caval Space.

BACKGROUND: The posterior retroperitoneoscopic adrenalec tomy has several advantages compared with the transperitoneal approach such as a shorter and more direct route to the target organ, no breach of the intraperitoneal space, and no required retraction of the adjacent organs. It also is a safe procedure with a short learning curve.1-5 This report presents a challenging case of an extra-adrenal paraganglioma located in the aorto-caval space and managed using the retroperitoneal approach. METHODS: A 39-year-old man was placed in the prone jackknife position, and three incisions were made in the right posterior abdominal wall for placement of the laparoscopic ports. The retroperitoneal space was entered with diathermy and blunt finger dissection, and retropneumoperitoneum was achieved with carbon dioxide insufflation pressure up to 18 mmHg. After identification of the right kidney and vessels, the tumor was meticulously dissected and excised with an energy device. The specimen was removed using a laparoscopic specimen retrieval bag, and the port sites were closed in layers. RESULTS: The operative time was 130 min, and the total blood loss was 30 ml. The tumor was diagnosed as a moderately differentiated extra-adrenal paraganglioma. The Von Hippel-Lindau gene mutation was detected using next-generation sequencing. CONCLUSIONS: The posterior retroperitoneoscopic approach is a safe, feasible, and effective method for excising an extra-adrenal paraganglioma even in the aorto-caval space. The authors suggest that this procedure is a useful surgical option for treatment of an aorto-caval paraganglioma for selected patients and by experienced surgeons.

Yonsei Experience of 5000 Gasless Transaxillary Robotic Thyroidectomies.

BACKGROUND: Since the use of robot systems in thyroid surgery was introduced in 2007, we have advanced a novel method of robotic thyroidectomy (RT) using a gasless transaxillary approach (TAA). We report our experience with this technique and detail the surgical outcome of 5000 robotic thyroidectomies. METHODS: From October 2007 to May 2016, we successfully performed 5000 robotic thyroidectomies using a gasless TAA at the Department of Surgery, Yonsei University Health System. The medical records of the patients are reviewed retrospectively, and the details of clinicopathologic characteristics, operation times, perioperative complications, and oncologic outcomes are analyzed. RESULTS: The 5000 patients with thyroid tumor (4804 with cancer and 196 with benign tumor) underwent RT using a gasless TAA. Mean operation time was 134.5 ± 122.0 min. The most common histologic subtype of thyroid cancer was papillary (98%), and the mean tumor size was 8.0 ± 6.0 mm. Stage I was found in 85.4% patients regarding tumor nodes metastasis staging. The 196 benign tumors consisted of 104 adenomatous hyperplasias (53.0%), 43 follicular adenomas (21.9%), 30 Graves' diseases (15.3%), and 19 others (9.7%). Postoperative complication occurred in 24.1% without any serious one, and overall morbidity tended to decrease over time. No disease-specific mortality was observed during the follow-up period. Locoregional recurrence was developed in 26 patients (0.5%). CONCLUSION: The authors have tried to improve RT technique using gasless TAA and achieved acceptable surgical outcomes. The rapid evolution of surgical robot technology and our constant effort to advance RT technique using gasless TAA would make it possible to reduce the perioperative morbidity and gain the best possible operative and oncologic outcomes.

Transaxillary robotic modified radical neck dissection: a 5-year assessment of operative and oncologic outcomes.

BACKGROUND: Robotic modified radical neck dissection (MRND) using a gasless transaxillary approach has been reported to be a safe and meticulous technique in patients with papillary thyroid carcinoma (PTC) and lateral neck node metastasis (N1b). Few studies, however, have attempted to assess the long-term oncologic outcomes of robotic MRND in these patients. This study aimed to compare perioperative and 5-year oncologic outcomes of robotic MRND with conventional open procedures in patients with N1b PTC. METHODS: Between September 2007 and February 2010, 193 patients with N1b PTC underwent total thyroidectomy and MRND by a single surgeon. Of these, 42 (21.8 %) underwent robotic procedures and 151 (78.2 %) underwent conventional open procedures. All patients received 3.7- to 5.5-GBq radioactive iodine (RAI) ablation, post-therapy whole-body scans (TxWBSs), and diagnostic WBS (DxWBSs) during follow-up. An exact 1:3 matching for age and stage was performed to minimize selection bias, and perioperative and 5-year oncologic outcomes were compared in the matched groups. RESULTS: The mean follow-up period was 66.0 months (range 60-90 months). Number of retrieved cervical lymph nodes (LNs) (p = .102) and postoperative ablation success rates (p = .864) were similar between the two groups. TSH-suppressed serum Tg concentrations after 5 years (0.7 ± 1.5 vs. 2.4 ± 14.1 ng/ml; p = .471) and recurrence rates in the robotic and open groups (1/41 [2.4 %] vs. 3/102 [2.9 %]; p = .864) were similar for the 5-year follow-up period. Four patients experienced recurrence: Three exhibited regional lymph node metastasis, and one showed bilateral lung metastases. CONCLUSION: The perioperative and 5-year oncologic outcomes were similar after robotic and conventional open MRND. Large, prospective randomized controlled trials with long-term follow-up data are needed to validate these results.

Long-term oncologic outcome of robotic versus open total thyroidectomy in PTC: a case-matched retrospective study.

PURPOSE: The role of the robot in thyroid surgery remains uncertain, and it is unclear whether robotic total thyroidectomy (R-TT) can be justified as a standard treatment for patients with thyroid cancer. This study compared the long-term operative results and oncologic outcomes of R-TT and conventional open TT (O-TT) after propensity score matching of the cohorts. METHODS: This study retrospectively evaluated patients with papillary thyroid cancer (PTC) who underwent TT with central compartment node dissection (CCND) by a single surgeon in tertiary medical center. Of the 833 patients, 94 (11.3 %) were lost to follow-up. 245 (33.2 %) underwent R-TT, and 494 (66.8 %) underwent O-TT. The mean follow-up duration was 74 (range 61-91) months. Propensity score matching in age, gender, tumor size, extrathyroidal invasion, multiplicity, bilaterality, and TNM stage identified 206 pairs of patients. The long-term oncologic outcomes were assessed in the R-TT and O-TT groups before and after adjustment for baseline covariates. RESULTS: After adjustment for baseline covariates, serum thyroglobulin (Tg) (p = 0.746) and anti-thyroglobulin antibody (TgAb) (p = 0.394) concentrations were similar in the two groups 5 years after surgery. Nine patients experienced locoregional recurrence, six in the O-TT and three in the R-TT group, with all recurrences in regional LNs. Disease-free survival (DFS) was similar in the R-TT and O-TT groups before matching (p = 0.890) and after adjustment for baseline covariates (p = 0.882). CONCLUSION: This represents the first report of 5-year surgical outcomes in patients who underwent R-TT for thyroid cancer. Long-term oncologic quality was similar after R-TT and O-TT.

Papillary thyroid cancer in black thyroid: a case report and literature review.

Background: Black thyroid is a rare incidental finding during surgery. We report the case of a patient with papillary thyroid cancer who was incidentally found to have minocycline-induced black thyroid. Case Description: A 29-year-old woman presented with a left thyroid nodule and metastatic papillary thyroid cancer involving the left neck level IV lymph nodes. She had a medical history of anxiety disorder with depression, severe acne, and rosacea, and had been taking benzodiazepines, selective serotonin reuptake inhibitors, isotretinoin, and minocycline for a few years. The patient underwent a total thyroidectomy with left central compartment neck dissection and ipsilateral modified radical neck dissection. A black thyroid gland was identified during thyroidectomy. During level IV dissection, we noticed a similar black discoloration in the adipose tissue of the lower neck. Pathological examination revealed brown pigmentation with few macrophages on several foci of the thyroid parenchyma. Brown pigmentation was not identified in the thyroid tumor, metastatic and normal lymph nodes, or background adipose tissue. Conclusions: We report a case of papillary thyroid microcarcinoma with cervical lymph node metastases in a black thyroid. The clinical findings were consistent with those of previous reports. Based on the literature, it remains unclear if this minocycline triggered finding is associated with an increased frequency and/or aggressiveness of thyroid carcinomas. In the absence of adequate evidence, prolonged minocycline users should ideally undergo routine thyroid assessment to identify possible malignancy.

Papillary thyroid cancer with suspicious uterine cervix metastasis: a case report and literature review.

Background: Distant metastasis (DM) of papillary thyroid cancer (PTC) is rare but significantly associated with decreased survival. Accurate clinical staging at initial diagnosis and during follow-up is essential. Case Description: We report the case of a 38-year-old woman diagnosed with PTC in the left isthmus who presented with a suspicious uterine cervix metastasis during follow-up after total thyroidectomy. She had neither medical history nor family history of thyroid cancer. During surgery, extensive central node metastases were found, and bilateral total thyroidectomy was performed. Even after three rounds of radioactive iodine (RAI) ablation, persistently elevated serum thyroglobulin (Tg) levels, combined with a suspicious finding on the whole-body scan (WBS) and fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT), led to the clinical suspicion of uterine cervix metastasis from PTC. Hysterectomy confirmed the pathology of chronic cervicitis. No hidden malignancy was observed. After surgery, negative imaging findings and decreased serum Tg levels were observed. Conclusions: This case contributes to the discussion of differential diagnostic problems in the setting of clinical and pathological investigations of PTC. However, based on the relevant rationales, through multidisciplinary discussion, this patient can ultimately obtain a better prognosis. Understanding the pitfalls of imaging modalities and continuous efforts to overcome the limitations of the diagnostic process are crucial for future treatment.

Frozen section analysis of central lymph nodes in papillary thyroid cancer: the significance in determining the extent of surgery.

Background: The indolent feature of papillary thyroid cancer (PTC) has recently led to an increase in less aggressive treatment options instead of total thyroidectomy (TT). We aimed to investigate the clinical significance of elective central compartment neck dissection (CCND) with intraoperative frozen analyses of the central lymph nodes (LNs) to determine the surgical extent of unilateral clinically node-negative PTC. Methods: We retrospectively reviewed the medical records of 290 patients with unilateral clinically node-negative PTC who underwent surgery and performed frozen analyses of the central LNs from 2020 to 2021 using our own nodal criteria with cut-off size 5 mm. The patients were divided and investigated according to the surgical extent and the National Comprehensive Cancer Network (NCCN) guidelines; diagnostic accuracy of the frozen analyses was estimated. Results: TT was performed in 16.2% of patients. The TT group had more metastatic nodes with a larger size, higher LN ratio (LNR), and more extranodal extension. The analyses based on the NCCN guidelines showed similar findings, but more completion TT was required compared with our criteria. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the frozen analyses were 94.6%, 100%, 100%, and 96.1%, respectively. Conclusions: Elective CCND with intraoperative frozen analyses is a highly reliable procedure that detects occult nodal metastasis in unilateral node-negative PTC patients. Our nodal criteria yielded significant aggressive nodal characteristics in the TT group while yielding less TTs compared with the NCCN guidelines. The concept and clinical significance of small-volume nodal metastasis in PTC should be further investigated.

Vitamin D Receptor Expression and its Clinical Significance in Papillary Thyroid Cancer.

Objective: This study aimed to evaluate the association between vitamin D receptor (an essential component in the vitamin D signaling pathway) and serum vitamin D as well as its clinical significance in papillary thyroid cancer. Methods: This prospective cohort study comprised patients with thyroid tumors who visited our hospital, from 2017 to 2018. The level of vitamin D receptor expression from thyroid tissue was measured in patients with thyroid tumor and evaluated for correlation with serum vitamin D levels and clinicopathologic characteristics of papillary thyroid cancer. Data from 501 patients with papillary thyroid cancer from The Cancer Genome Atlas database were analyzed. Results: Increased vitamin D receptor protein and mRNA expression were observed in papillary thyroid cancer compared to those in normal and benign tissues. Lower vitamin D receptor protein expression was associated with high TNM stage papillary thyroid cancer and low p21 protein expression. Lower relative vitamin D receptor mRNA expression in papillary thyroid cancer was associated with low serum 25-hydroxyvitamin D level. The Cancer Genome Atlas database showed a positive correlation among mRNA expression of vitamin D receptor, CYP24A1, and p21. Conclusions: An association between decreased vitamin D receptor protein expression and advanced stage papillary thyroid cancer, and a correlation between low vitamin D receptor mRNA expression with low serum 25-hydroxyvitamin D level was observed. Low vitamin D receptor expression in papillary thyroid cancer was shown to positively correlate with low serum vitamin D level and disease aggressiveness.

TERT Promoter and BRAF V600E Mutations in Papillary Thyroid Cancer: A Single-Institution Experience in Korea.

Telomerase reverse transcriptase (TERT) promoter mutation has been investigated for its clinical and prognostic significance in aggressive papillary thyroid cancer (PTC). In this study, we aimed to assess the prevalence, clinicopathologic features, and treatment outcomes of TERT mutation-positive PTCs along with the common BRAF V600E mutation. We performed mutational analyses for BRAF and the TERT promoter in thyroid cancer patients who had undergone surgery at our institution since 2019. We reviewed and analyzed 7797 patients with PTC in this study. The prevalence of BRAF V600E and TERT promoter mutations was 84.0% and 1.1%, respectively. Multifocal gene mutations in bilateral PTCs were identified. TERT promoter mutations were associated with older age, larger tumor size, tumor multifocality, tumor variants, advanced stages, more adjuvant radioactive iodine treatment (RAI), higher stimulated serum thyroglobulin level before RAI, and more uptakes in the regions outside the surgical field on a post-RAI whole-body scan. The coexistence of BRAF V600E and TERT promoter mutations exacerbated all clinicopathologic characteristics. The frequency of TERT promoter mutations was the lowest in this study, compared to previous studies. TERT promoter mutations consistently correlated with aggressive PTCs, and the synergistic effect of both mutations was evident. Specific clinical settings in our institution and in Korea may have led to these distinctive results. Prospective multicenter studies with longer follow-up periods are required to establish valuable oncologic outcomes.

Incidental paratracheal air cyst in papillary thyroid cancer patient: a case report.

Paratracheal air cyst (PTAC) is a collection of air in the right posterior side of the trachea with an uncertain etiology. We report a papillary thyroid cancer patient with a PTAC that was removed during thyroid cancer surgery. A 68-year-old woman was diagnosed with right papillary thyroid cancer with suspicion of central lymph node metastasis. She had a history of hypertension and a rear-end collision car accident 20 years prior. On computed tomography, an ovoid cyst was incidentally found in the paratracheal region at the thoracic inlet level. Emphysematous lung with an obstructive lung defect was noted without any symptoms. Bilateral total thyroidectomy with ipsilateral central compartment neck dissection was indicated for the patient. During surgery, removal of the cyst was inevitable for complete central neck dissection. Histopathologic analysis revealed an etiology of tracheal mucus sprouting through weak trachea points. No postoperative complications occurred. The patient continued on levothyroxine medication without further radioactive iodine therapy. After 6 months, follow-up ultrasound showed no evidence of recurrence. We hypothesized that obstructive lung disease with impaired lung function or trauma history might have contributed to the development of PTAC. Future studies are needed to determine if PTACs have any association with obstructive lung disease or trauma.

Feasibility of lateral sentinel lymph node biopsy in medullary thyroid cancer: Surrogate tool for determining prophylactic lateral neck dissection-A pilot study.

BACKGROUNDS: This study aimed to evaluate usefulness of lateral sentinel lymph node biopsy (SLNB) in determining lateral neck dissection (LND) of patients with medullary thyroid cancer (MTC). METHODS: Sixteen patients with MTC were enrolled in the study from January 2013 to June 2019. Intratumoral injection of technetium (Tc)-99m phytate followed by lymphoscintigraphy was performed preoperatively. Lateral sentinel lymph nodes were detected by a collimated gamma probe and underwent frozen analysis. Ipsilateral LND was performed in all patients to assess lateral LN status. RESULTS: The identification rate of sentinel lymph nodes (SLNs) detected by radioisotope was 87.5% (14 of 16 patients). The sensitivity, specificity, positive predictive value, and negative predictive value of frozen analyses were 66.7%, 100%, 100%, and 91.6%, respectively. Based on final histopathology, however, the diagnostic values of lateral SLNB were all 100%. CONCLUSIONS: This study showed that lateral SLNB can be a promising surgical tool for decisions on LND in patients with MTC.

Cystic Lateral Lymph Node Metastases From Papillary Thyroid Cancer Patients.

OBJECTIVES/HYPOTHESIS: Papillary thyroid carcinoma (PTC) tends to metastasize rather early to local lymph nodes (LNs). Incidences of cystic LN metastases is relatively rare compared with that of solid LN metastases. Few studies have attempted to assess the characteristics in these patients. This study aimed to compare the clinicopathologic characteristics and surgical outcomes between patients with cystic LN metastases and those with solid LN metastases. STUDY DESIGN: Retrospective cohort study. METHODS: We retrospectively reviewed the data of 1,028 patients with N1b PTC who underwent bilateral total thyroidectomy with central compartment neck dissection and modified radical neck dissection between January 2005 and September 2011. Of these, 136 (13.2%) had cystic LN metastases and 892 (86.8%) had solid LN metastases. Clinicopathologic characteristics and surgical outcomes were compared between these two patient groups. RESULTS: The proportion of patients with thyroid tumor multifocality was relatively higher in the cystic node cohort (19.9% vs. 12.7%, P = .048). The number of total metastatic LNs and positive lateral LNs was slightly higher in the cystic node cohort (11.3 ± 8.9 vs. 9.7 ± 7.5, P = .029 and 6.9 ± 6.3 vs. 5.5 ± 4.6, P = .018, respectively). The proportion of patients with recurrence was higher in the cystic node cohort (14.0% vs. 3.0%, P < .001). Multivariate analysis indicated that cystic nodes were a significant risk factor for recurrence (hazard ratio: 5.265, 95% confidence interval: 2.898-9.563). CONCLUSIONS: This study demonstrates that cystic lateral LN metastases are associated with aggressive tumor behavior in PTC patients. and that their presence is a significant independent prognostic factor for disease-free survival. LEVEL OF EVIDENCE: 2b Laryngoscope, 2020.

Current trends in the features of male thyroid cancer: Retrospective evaluation of their prognostic value.

This study aimed to compare the clinicopathologic characteristics and oncologic outcomes of papillary thyroid cancer (PTC) patients according to sex. Then, we validated prognostic variables to determine whether sex is a significant prognostic factor for PTC.Between January 2007 and December 2010, 1232 men and 7276 women PTC patients underwent surgery. The patient characteristics and 5-year oncologic outcomes were compared. The stepwise Cox proportional hazards model determined the significance of survival variables.Men PTC patients had more lymph node (LN) metastases than women, both in the total (P < .0001) and hemithyroidectomy (P < .0001) patients. Men and women showed similar 5-year recurrence-free survivals, both in total (P = .815) and hemithyroidectomy (P = .148) patients. The tumor size and the number of positive central nodes were associated with tumor recurrence, but not sex.Sex was not an independent prognostic factor for tumor recurrence. Multicenter clinical studies with long-term follow-ups are needed to validate these results.

Oncologic outcomes in patients with 1-cm to 4-cm differentiated thyroid carcinoma according to extent of thyroidectomy.

BACKGROUND: Recent guidelines advocate unilateral thyroidectomy for low-risk 1-cm to 4-cm differentiated thyroid cancer (DTC). This study was designed to examine the association between the extent of thyroidectomy and oncologic outcomes in patients with 1-cm to 4-cm DTC. MATERIALS AND METHODS: From April 1978 to December 2011, 16 057 patients with DTC underwent thyroidectomy at Yonsei University Hospital. Among them, 5266 (32.8%) patients were classified as having 1-cm to 4-cm DTC and were enrolled in this study. Clinicopathologic features and prognostic results (disease-free survival [DFS] and disease-specific survival [DSS] rates) were analyzed by retrospective medical record review. The mean follow-up duration was 57.3 ± 58.1 months. RESULTS: Of tumor subtypes in the study group, papillary thyroid carcinoma was the most common (97.5%) and follicular thyroid carcinoma occurred at a rate of 2.5%. In this study, the mean tumor size was 1.84 ± 0.74 cm. Patients had extrathyroidal extension (69.3%), multiplicity (35.1%), bilaterality (26.4%), central lymph node metastasis (53.0%), and lateral neck node metastases (19.9%). Of the 5266 patients, 4292 (81.5%) underwent total thyroidectomy and 974 (18.5%) had lobectomies. Recurrence rates in the total thyroidectomy and lobectomy groups were 5.7% and 9.4%, respectively. The lobectomy group had lower DFS (P = .007) and higher DSS (P = .034) than the total thyroidectomy group. A multivariate analysis for DFS revealed that tumor size, N classification, and extent of thyroidectomy were independent risk factors. On multivariate analysis, independent risk factors for DSS were age, sex, tumor size, and M classifications. CONCLUSION: Although extent of thyroidectomy does not affect DSS, total thyroidectomy is beneficial for reducing recurrence in patients with 1-cm to 4-cm DTC. However, if such tumors have such low-risk features as being unifocal, intrathyroidal, and lymph node metastasis-negative, extent of thyroidectomy does not affect oncologic outcome and lobectomy may be sufficient.

Gasless, transaxillary robotic neck dissection: the technique and evidence.

Robotic neck dissection (ND) for the thyroid cancer with lateral neck metastasis case is one of the emerging surgical techniques, and has been highlighted as minimally invasive surgical technique recently. Gasless, transaxillary robotic approach enabled the surgeon to do meticulous and precise dissection in the complex procedure, such as ND, eventually showed favorable surgical safety and outcomes, as well as superior functional and cosmetic benefits. In this article, the author would like to introduce the detailed techniques and secure evidences for the gasless, transaxillary robotic ND.

Usefulness of dynamic risk stratification in pediatric patients with differentiated thyroid carcinoma.

PURPOSE: Recently, the American Thyroid Association (ATA) dynamic risk stratification (DRS) has been verified to be more valuable than the static anatomical staging system for predicting prognosis in patients with differentiated thyroid carcinoma (DTC). The purpose of this retrospective study was to compare the clinical usefulness of DRS, which is based on the response to initial treatment, with that of ATA initial risk stratification in pediatric patients. METHODS: A total of 144 pediatric patients underwent thyroid operation from August 1982 to December 2013 at Yonsei University Hospital (Seoul, Korea). Among them, 128 patients with complete clinical data were enrolled in this study. Clinicopathologic features and surgical outcomes were retrospectively analyzed by medical chart review. The mean follow-up duration was 11.5 years. RESULTS: The mean tumor size was 2.1 cm; 80.4% of patients were diagnosed with conventional papillary thyroid carcinoma, and 7.0% of patients were diagnosed with follicular thyroid carcinoma. Low-risk patients had the highest probability of an excellent response to initial treatment (66.6%). High-risk patients had the highest probability of a structural incomplete response (100%) and the lowest probability of an excellent response (11.1%). The ATA risk stratification and the DRS system were independent risk factors for disease-free survival (DFS) (P = 0.041 and P < 0.001, respectively). CONCLUSION: The DRS system, which is based on the response to initial treatment, can offer more useful prognostic information compared with ATA risk stratification in pediatric patients with DTC.

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 ±â€Š62.51 months.In this study, mean tumor size was 1.94 ±â€Š1.40 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.