Recognizing Persistent Disease in Well-Differentiated Thyroid Cancer and Association with Lymph Node Yield and Ratio

Predictors of treatment response in lymphogenic metastasized papillary thyroid cancer: a histopathological study

BACKGROUND

Lymph node metastases in papillary thyroid cancer (PTC) increase the risk for persistent and recurrent disease. Data on the predictive value of histopathological features of lymph node metastases, however, are inconsistent. The aim of this study was to evaluate the prognostic significance of known and new histopathological features of lymph node metastases in a well-defined cohort of PTC patients with clinically evident lymph node metastases.

METHODS

A total of 1042 lymph node metastases, derived from 129 PTC patients, were reexamined according to a predefined protocol and evaluated for diameter, extranodal extension, cystic changes, necrosis, calcifications, and the proportion of the lymph node taken up by tumor cells. Predictors for a failure to achieve a complete biochemical and structural response to treatment were determined.

RESULTS

The presence of more than 5 lymph node metastases was the only independent predictor for a failure to achieve a complete response to treatment (odds ratio [OR] 3.39 [95% CI, 1.57-7.33], P < .05). Diameter nor any of the other evaluated lymph node features were significantly associated with the response to treatment.

CONCLUSIONS

Detailed reexamination of lymph nodes revealed that only the presence of more than 5 lymph node metastases was an independent predictor of failure to achieve a complete response to treatment. No predictive value was found for other histopathological features, including the diameter of the lymph node metastases. These findings have the potential to improve risk stratification in patients with PTC and clinically evident lymph node metastases.

Lymph Node Ratio Predicts Recurrence in Patients with Papillary Thyroid Carcinoma with Low Lymph Node Yield

The American Thyroid Association risk stratification system suggests that having >5 metastatic lymph nodes (LNs) increase the recurrence risk in patients with papillary thyroid carcinoma (PTC). However, little is known about PTC with <5 harvested LNs. This study aimed to stratify patients with low-LN-yield (low-LNY) PTC based on lymph node ratios (LNRs). From 2007 to 2017, 6317 patients who underwent thyroidectomies were diagnosed with PTC at Seoul St. Mary's Hospital, and 909 patients with low LNYs were included in the study. Tumor recurrence was compared based on LNR. The LNR cutoff was determined using a receiver operating characteristic curve. Forty-six patients (5.1%) experienced recurrences over a mean follow-up period of 127.24 ± 33.6 months (range, 5-190 months). The cutoff for the low-LNR (n = 675) and high-LNR (n = 234) groups was 0.29 (AUC = 0.676, 95% CI = 0.591-0.761, p < 0.001). The recurrence rate was significantly higher in the high-LNR group compared to the rate in the low-LNR group (12.4% vs. 2.5%, p < 0.001). Multivariate analysis using Cox regression revealed that tumor size and LNR ≥ 0.29 were independent prognostic factors for recurrence. Therefore, LNR can be utilized to stratify the risk of recurrence in patients with low-LNY PTC.

The lymph node yield in the initial lateral neck dissection predicts recurrence in the lateral neck of papillary thyroid carcinoma: a revision surgery cohort study

BACKGROUND

This study aimed to evaluate the relationship between lateral lymph node yield (LLNY) and the ratio of lateral positive lymph nodes to lymph node yield (LPLR) from initial lateral neck dissection (LND) in patients with papillary thyroid carcinoma (PTC), as well as the risk of recurrence in patients undergoing LND reoperations.

METHODS

This retrospective cohort study enrolled patients with PTC who underwent revision LND between 1 January 2012, and 31 December 2021. The initial and revised clinical data were retrieved. Patient demographics, clinicopathological features, clinical records, and follow-up information were also reviewed. LLNY and LPLR were determined during the initial LND.

RESULTS

In total, 156 patients with PTC were included in this study, with a median follow-up of 36.5 months; 107 had recurrent lateral neck disease. The optimal LLNY and LPLR cutoff values for recurrent/persistent disease were 24.5 and 32.74%, respectively. The high-risk group (LLNY<25) had the lowest recurrence-free survival rate compared with to moderate-risk group (LLNY≥25, LPLR≥32.74%) and low-risk group (LLNY≥25, LPLR<32.74%) ( P <0.001). The moderate-risk group had lower recurrence-free survival than the low-risk group. Multivariate analysis revealed that an LLNY less than 25 in the initial LND was an independent risk factor for recurrence/persistence of lateral neck ( P <0.001).

CONCLUSIONS

This study identified that LLNY and LPLR were associated with recurrence/persistence in PTC patients at the time of revision surgery was performed.

Lymph node ratio in lateral neck is an independent risk factor for recurrence-free survival in papillary thyroid cancer patients with positive lymph nodes

BACKGROUND

The purpose of this study was to explore the impact of the lymph node ratio on prognosis in papillary thyroid cancer patients with lymph node metastasis.

METHODS

Data from papillary thyroid cancer patients with positive nodes who were initially treated at our institution during 2015-2016 were analysed. Univariate and multivariate Cox proportional hazard models were adopted to predict prognostic factors. A receiver operating characteristic (ROC) curve was used to find the best cut-off value of the lymph node ratio (LNR). Kaplan-Meier curves were used to show the relationship between the LNR in the lateral neck and recurrence-free survival.

RESULTS

The median follow-up time was 64.6 months, and recurrence occurred in 16 of 662 patients (2.27%). Univariate analysis showed that male sex, primary tumour size (&gt;17 mm), visible extrathyroidal extension, LNR in the central neck (&gt;0.5), LNR in the lateral neck (&gt;0.10), and visible extranodal extension were significantly correlated with recurrence-free survival (RFS) (p &lt; 0.05). Multivariate analysis using the Cox proportional hazards model showed that the LNR in the lateral neck was an independent risk factor for RFS (p = 0.039; HR 14.76).

CONCLUSION

The LNR in the lateral neck was an independent risk factor for recurrence-free survival. For patients with a high lymph node ratio in the lateral neck, more frequent follow-up might be needed.

Risk probability model for residual metastatic lymph node in patients with papillary thyroid microcarcinoma undergoing cervical central lymph node dissection

To establish a risk probability model for residual metastatic lymph nodes in patients with papillary thyroid microcarcinoma (PTMC) after cervical central lymph node dissection (CLND). The clinical data of patients with PTMC treated in the First Affiliated Hospital of Kunming Medical University from 2007 to 2020 were retrospectively reviewed. All patients underwent thyroidectomy with CLND, and at least one lymph node was examined. Based on the distribution characteristics of metastatic lymph nodes from this retrospective cohort, a probabilistic model for the risk of residual metastatic lymph node was established. β-Binomial distribution was used to estimate the probability of residual metastatic lymph node as a function of the number of lymph nodes examined. Among 5399 patients included in the probabilistic model, central lymph node metastases were observed in 1664 cases (30.8%). After model correction, the real lymph node metastasis rate increased from 30.8% to 38.9%. The probability of false negative of central lymph node was estimated to be 31.3% for patients with a single node examined, while decreased to 10.0% and 4.9% when 7 and 12 nodes were examined, respectively. In the sensitivity analysis limited to patients with or without Hashimoto thyroiditis, the performance of probability model was also satisfactory. The established risk probability model in this study quantifies the risk of residual metastatic lymph nodes after CLND in patients with PTMC, which can be used as complementary indicators for the risk of recurrence/persistence disease at postoperative evaluation. The study also provides a new method to evaluate the impact of residual metastatic lymph nodes on the prognosis of tumor patients through retrospective data.