Calcitonin-negative medullary thyroid carcinoma(CNMTC)is a rare subtype of medullary thyroid carcinoma,characterized by normal serum calcitonin levels,which often leads to misdiagnosis or missed diagnosis.The pathogenesis of CNMTC remains unclear and may involve impaired secretion mechanisms or assay-related false negatives.Diagnostic approaches include ultrasound-guided fine needle aspiration cytology,serum CEA and ProGRP measurements,and RET gene testing.Surgical resection remains the mainstay of treatment,while neoadjuvant therapy may be considered in selected cases.This review summarizes recent advances in the understanding,diagnosis,treatment,and prognosis of CNMTC,aiming to provide clinical guidance for better management of this challenging condition.

Objective:To investigate the clinical predictive value of Ki67 proliferation index combined with preoperative serum Ctn for postoperative biochemical cure of medullary thyroid carcinoma (MTC) .Methods:Clinical data were collected from Dec. 2008 to Dec. 2024 from 90 patients with surgically confirmed MTC at China-Japan Union Hospital of Jilin University. The optimal cut-off value for preoperative Ctn prediction of biochemical cure (171.18pg/mL) was determined by the ROC curve; the Ki67 proliferation index cut-off value was adopted from the international MTC grading system standard (5%). Patients were divided into three groups based on the above cutoff values: double-low group (Ki67 <5% and Ctn <171.18pg/mL, n=23), single-high group (Ki67 ≥5% and Ctn <171.18pg/mL or Ki67 <5% and Ctn ≥171.18pg/mL, n=49), and double-high group (Ki67 ≥5% and Ctn ≥171.18pg/mL, n=18). The Kaplan-Meier method (Log-Rank and Trend test) was used to compare the differences in biochemical cure rates between groups, and the Cox proportional risk model was used to analyze the risk factors affecting biochemical cure. Results:The correlation between preoperative Ctn and Ki67 proliferation index was not significant. The three groups differed significantly in gender, tumor distribution, tumor size, vascular invasion, N stage, TNM stage, and biochemical cure ( P<0.05), with the double-high group being significantly associated with larger tumors, later N stage and TNM stage, and lower biochemical cure ( P<0.001). Kaplan-Meier analysis showed that the biochemical cure rate in the double-high, single-high, and double-low groups showed a stepwise improvement.Cox univariate analysis showed that tumor size, N stage, TNM stage, preoperative Ctn, and Ki67 combined with Ctn were risk factors for failure to biochemically cure; multivariate analysis confirmed that the double-high group was an independent risk factor ( P<0.05). In the single-high group, the biochemical cure rate of patients in the low Ki67-high Ctn group was lower than that of the high Ki67-low Ctn group and more malignant. Ki67 had less effect on biochemical cure and disease-free survival at the low Ctn level, and Ki67 was an independent risk factor for failure to biochemically cure at the high Ctn level ( P=0.023) and was significantly associated with disease-free survival ( P=0.004) . Conclusions:Serum Ctn is more sensitive than Ki67 index in predicting biochemical cure after MTC, and the correlation between the two was weak. Ki67 proliferation index alone has limited prognostic value, but combines with preoperative Ctn significantly optimize the prognostic assessment of patients.The role of Ki67 index varied at different Ctn levels.

Objective:To investigate the clinical predictive value of Ki67 proliferation index combined with preoperative serum Ctn for postoperative biochemical cure of medullary thyroid carcinoma (MTC) .Methods:Clinical data were collected from Dec. 2008 to Dec. 2024 from 90 patients with surgically confirmed MTC at China-Japan Union Hospital of Jilin University. The optimal cut-off value for preoperative Ctn prediction of biochemical cure (171.18pg/mL) was determined by the ROC curve; the Ki67 proliferation index cut-off value was adopted from the international MTC grading system standard (5%). Patients were divided into three groups based on the above cutoff values: double-low group (Ki67 <5% and Ctn <171.18pg/mL, n=23), single-high group (Ki67 ≥5% and Ctn <171.18pg/mL or Ki67 <5% and Ctn ≥171.18pg/mL, n=49), and double-high group (Ki67 ≥5% and Ctn ≥171.18pg/mL, n=18). The Kaplan-Meier method (Log-Rank and Trend test) was used to compare the differences in biochemical cure rates between groups, and the Cox proportional risk model was used to analyze the risk factors affecting biochemical cure. Results:The correlation between preoperative Ctn and Ki67 proliferation index was not significant. The three groups differed significantly in gender, tumor distribution, tumor size, vascular invasion, N stage, TNM stage, and biochemical cure ( P<0.05), with the double-high group being significantly associated with larger tumors, later N stage and TNM stage, and lower biochemical cure ( P<0.001). Kaplan-Meier analysis showed that the biochemical cure rate in the double-high, single-high, and double-low groups showed a stepwise improvement.Cox univariate analysis showed that tumor size, N stage, TNM stage, preoperative Ctn, and Ki67 combined with Ctn were risk factors for failure to biochemically cure; multivariate analysis confirmed that the double-high group was an independent risk factor ( P<0.05). In the single-high group, the biochemical cure rate of patients in the low Ki67-high Ctn group was lower than that of the high Ki67-low Ctn group and more malignant. Ki67 had less effect on biochemical cure and disease-free survival at the low Ctn level, and Ki67 was an independent risk factor for failure to biochemically cure at the high Ctn level ( P=0.023) and was significantly associated with disease-free survival ( P=0.004) . Conclusions:Serum Ctn is more sensitive than Ki67 index in predicting biochemical cure after MTC, and the correlation between the two was weak. Ki67 proliferation index alone has limited prognostic value, but combines with preoperative Ctn significantly optimize the prognostic assessment of patients.The role of Ki67 index varied at different Ctn levels.

Calcitonin-negative medullary thyroid carcinoma(CNMTC)is a rare subtype of medullary thyroid carcinoma,characterized by normal serum calcitonin levels,which often leads to misdiagnosis or missed diagnosis.The pathogenesis of CNMTC remains unclear and may involve impaired secretion mechanisms or assay-related false negatives.Diagnostic approaches include ultrasound-guided fine needle aspiration cytology,serum CEA and ProGRP measurements,and RET gene testing.Surgical resection remains the mainstay of treatment,while neoadjuvant therapy may be considered in selected cases.This review summarizes recent advances in the understanding,diagnosis,treatment,and prognosis of CNMTC,aiming to provide clinical guidance for better management of this challenging condition.

Objective:To investigate the efficacy and prognosis of different surgical approaches in sporadic medullary thyroid carcinoma.Methods:A retrospective analysis was conducted on 101 patients with sporadic medullary thyroid carcinoma (MTC) who underwent surgical treatment at the Department of Thyroid Surgery, China-Japan Union Hospital of Jilin University, from Feb. 2009 to Nov. 2023. The patients included 36 males and 75 females, with a male-to-female ratio of 1:2.1. The median age of the patients was 47 years old, with an age range of 21 to 72 years old. The study divided participants into two groups based on their surgical methods: an observation group (78 cases) and a control group (23 cases). The observation group received surgical methods in accordance with expert consensus, while the control group did not. The study compared the efficacy and prognosis of the two groups.Results:Statistical differences were found between the two groups in terms of stage II and III in TNM staging, intraoperative frozen pathological findings, number of lymph node resections in the central group, number of lymph node metastases in the central group, number of lymph node resections in the lateral cervical region, postoperative follow-up time, and five-year postoperative serum procalcitonin (Ctn) levels ( P<0.05) .Both groups of patients obtained a significant decrease in Ctn after surgical treatment. In the observation group, Ctn was at the remission level in 57 cases (73.1%), at the stable level in 13 cases (16.7%), and at the progression level in 8 cases (10.2%), while in the control group, Ctn was at the remission level in 20 cases (86.9%), at the progression level in 3 cases (13.1%), and there were no patients at the stable level after the operation.One patient (1.3 per cent) in the observation group had a recurrence after surgery; Two patients (8.7 per cent) in the control group had a recurrence. Conclusions:Standardised and thorough surgery can maximise the clearance of metastatic lymph nodes, effectively reduce the recurrence rate, achieve better efficacy, and improve the long-term prognosis of patients without increasing the risk of surgery and postoperative complications.