Subclassification of Tumor Extension and Nodal Metastasis in Papillary Thyroid Cancer to Improve Prognostic Accuracy of the Eighth Edition of the Tumor–Node–Metastasis Classification

Comparison of the prognostic value of AJCC cancer staging system 7th and 8th editions for differentiated thyroid cancer

BACKGROUND

In the last American Joint Committee on Cancer/Tumor, Node, Metastasis (AJCC/TNM) 8th edition (TNM8), several changes were introduced to this risk stratification system to improve the prognosis of differentiated thyroid cancer (DTC).

AIM

To validate the impact of TNM8 vs. TNM 7th edition (TNM7) in DTC in terms of predictive value in two hospitals from Buenos Aires, Argentina.

METHODS

Retrospective study of DTC patients from two institutions. Reclassification from TNM7 to TNM8, disease-specific survival (DSS), and final clinical outcomes at the end of follow-up (recurrent/persistent structural disease) (median 5 years) were analyzed. The proportion of variation explained (PVE) was used to compare the predictive capability of DSS of both classification systems.

RESULTS

Reclassification of 245 patients, aged (mean ± SD) 55 ± 15.36 years, 91% women, to TNM8 from TNM7 showed: 82% vs 57% stage I (SI), 10% vs 8.5% SII, 5% vs 22% SIII, 3% vs 12% SIV (p < 0.01). Forty percent of the population was downstaged with TNM8. Ten-year DSS rates for SI, SII, SIII and SIV in TNM7 were 100, 100, 100 and 74%, respectively and in TNM8: 97.6, 100, 100 and 37.5%, respectively. Out of 4 disease-specific deaths in SIV TNM7, one was subclassified to SI TNM8, corresponding to a 53-year-old patient with structural persistence. PVE for TNM8 (29%) was more than twice that of TNM7 (13%).

CONCLUSION

In this Argentinian DTC patients sample, it was confirmed that the new TNM8 classification is more accurate in predicting survival attributable to cancer than its previous version.

The number of metastatic lymph nodes optimizes staging in patients aged 55 years or older with papillary thyroid cancer

PURPOSE

Current staging criteria for papillary thyroid cancer (PTC) do not include the number of metastatic lymph nodes (LNs), which is highly predictive of survival in multiple cancers. The LN metastasis burden is particularly relevant for older adults with thyroid cancer because of their poor prognosis. We examined a modified staging system for this population utilizing node number (Nn).

METHODS

Overall, 14,341 patients aged 55 years or older with stage I-IVB PTC were identified in the 2004-2015 Surveillance, Epidemiology and End Results database. Cox regression models were conducted to test the relationship between positive LN number and PTC-specific survival (PTCSS). Independent training/validation sets were used to derive and validate a new revised TNnM grouping. The 8th edition American Joint Committee on Cancer TNM staging system was compared with TNnM stage by calculating the 10-year PTCSS rates, Harrell's concordance index (C-index), and Akaike's information criterion (AIC).

RESULTS

An increase in number of LN metastases was identified as an independent, negative prognostic factor for PTCSS in multivariate analysis. 10-year PTCSS for stage I-IVB based on the AJCC 8th edition TNM were 98.83%, 93.49%, 71.21%, 72.95%, and 58.52%, respectively, while 10-year PTCSS for the corresponding stage in the TNnM were 98.59%, 92.2%, 83.26%, 75.24%, and 56.73%, respectively. The revised TNnM stage was superior, with a higher C-index and a lower AIC in both the training and validation cohorts.

CONCLUSION

The TNnM staging system for PTC patients ≥ 55 years could be associated with improved outcomes. External validation studies of this system are warranted.

Impact of gross extrathyroidal extension into major neck structures on the prognosis of papillary thyroid carcinoma according to the American Joint Committee on Cancer eighth edition

This study investigated the impact of gross extrathyroidal extension into major neck structures on the prognosis of papillary thyroid carcinoma according to changes in the American Joint Committee on Cancer (AJCC)/Tumor-Node-Metastasis staging system. Overall, 183 patients with gross extrathyroidal extension into major neck structures were enrolled. The 10-year disease-specific survival (DSS) of patients in each stage showed appropriate correlation and stratification with the AJCC eighth edition. However, the 10-year DSS rate in stage III was better than the expected 10-year DSS rate, according to the AJCC eighth edition. Patients in stage III were subcategorized into three new groups: stage IIIA, patients with only recurrent laryngeal nerve invasion; stage IIIB, patients with superficial invasion of the aerodigestive tract; and stage IIIC, patients with intraluminal invasion of the aerodigestive tract. The prognostic differences among these three groups and stage IVA were examined. Although the DSS rate of patients in stage IIIA was excellent, that of patients with T4a disease was worse due to the progression of aerodigestive tract infiltration. Of the four groups, the time to locoregional recurrence was the shortest for patients in stage IVA. The distant recurrent-free survival for patients in stages IIIC and IVA tended to be worse than those for patients in stages IIIA and IIIB. These results indicate that the progression of aerodigestive tract infiltration has an impact on the incidence of distant recurrence, and the presence of T4b disease has an impact on the incidence of distant and locoregional recurrences.

Diagnostic and prognostic value of preoperative systemic inflammatory markers in anaplastic thyroid cancer

BACKGROUND

Easily accessible, generalized, and inexpensive methods are expected to differentiate anaplastic thyroid carcinoma (ATC) from advanced differentiated thyroid cancer (aDTC). We aimed to explore potential diagnostic and prognostic value of systematic inflammatory markers (SIMs) in ATC and aDTC.

METHODS

About 22 ATC, 101 aDTC, and 100 matched early DTC patients were analyzed retrospectively. SIMs included the comprehensive index, neutrophil-monocyte-platelet-to-lymphocyte ratio (NMPLR) and the previously reported ones. Receiver operating characteristic, Kaplan-Meier, and COX regression analyses were mainly conducted.

RESULTS

NMPLR exhibited the highest area under the curve value 0.806 (P < .0001) to diagnose ATC from aDTC. NMPLR was identified as an independent risk factor for overall survival (OS) (hazard ratio [HR]: 47.821, 95% confidence interval [CI], 2.863-798.765, P = .007) in ATC, as well as for OS (HR: 7.360, 95% CI, 1.620-33.430, P = .010) and recurrence-free survival (HR: 4.172, 95% CI, 1.139-15.286, P = .031) in aDTC. Taken both refractory types (ATC and aDTC) together, NMPLR could independently predict OS (HR: 6.470; 95% CI, 2.134-19.616; P = .001).

CONCLUSION

NMPLR is a generalized index. It showed excellent potential in differential diagnosis and survival prediction in refractory thyroid cancer. However, it needs to be validated in larger cohort and clinical practice.

Prognostic Value of Extranodal Tumor Extension in Papillary Thyroid Carcinoma: Proposal for Upstaging of Cases with Extranodal Tumor Extension

BACKGROUND

Recently, we have created a revised version of the eighth edition of the tumor-node-metastasis classification for papillary thyroid carcinomas (PTCs) by subdividing the T4a (T4a1 [moderate] and T4a2 [significant]) and N (N1 [N ≤ 3 cm] and N2 [N > 3 cm]) classifications. This re-staging better stratified patient outcomes. In this study, we investigated the prognostic significance of extranodal tumor extension (LNEx) in PTC.

METHODS

Five thousand six hundred and eighty-three patients with PTC surgically treated in Kuma Hospital were enrolled. We evaluated LNEx based on intraoperative findings.

RESULTS

One hundred and twenty-seven patients (2%) displayed LNEx. In contrast to what we observed for extrathyroid extension, the prognostic value of LNEx did not change based on the organ that had been invaded, and we therefore analyzed LNEx patients as a single group. In patients aged 55 or older, LNEx independently affected patients' prognoses, as did T4a2 and N2. The cancer-specific survival (CSS) of patients in Stage I but having LNEx demonstrated the similar prognosis to patients in Stage II. Further, in the subset analysis for Stage II patients aged 55 or older, LNEx had a significant prognostic value for CSS in both the univariate and multivariate analyses, as did N2. The CSS of Stage II patients aged 55 or older with LNEx did not differ from that of Stage III patients.

CONCLUSIONS

It is appropriate that, similar to T4a2 or N2 patients, LNEx-positive patients younger than 55 years in Stage I and those aged 55 or older in Stage II are re-staged to II and III, respectively.