Evaluating the predicted impact of changes to the AJCC/TMN staging system for differentiated thyroid cancer (DTC): A prospective observational study of patients in South East Scotland

Abstract

Objectives To assess the impact of the eighth edition AJCC/TMN staging system on patients with new diagnoses of differentiated thyroid cancers presenting to our regional multidisciplinary team meetings. Design We analysed Endocrine Cancer MDT meeting records from 2009 to 2015 to identify all patients in the region presenting with a new diagnosis of differentiated thyroid cancer. We re‐staged patients according to the eighth edition AJCC/TNM staging classification and analysed the survival outcomes of patients in each stage under the seventh and eighth systems. Setting Tertiary referral centre in South East Scotland (NHS Lothian). Participants Three hundred and sixty‐one patients were newly diagnosed with DTC within South East Scotland during the study period and met our inclusion criteria. Main outcome measures: Disease‐specific mortality at any time during follow‐up. Results In total, 119 of 361 (33%) patients were re‐staged when the eighth edition AJCC/TMN system was applied. The number of patients classified as having advanced stage (III/IV) disease fell from 76 (21%) to 8 (2%). The most common reason for down‐staging was re‐classification of tumour size, a factor in 96 (80.7%) down‐staged patients. The five‐year disease‐specific survival of the cohort overall was 98%. Overall, 7 (1.9%) thyroid cancer–related deaths occurred during follow‐up, three of whom were down‐staged. Conclusions On implementation of the eighth edition of the AJCC/TMN staging system, we expect many patients who would previously have been considered to have advanced thyroid cancer will now be classified as early stage. This will accurately reflect their excellent survival outcomes.

Long‐term predictive value of highly sensitive thyroglobulin measurement

“…To the best of our knowledge, the present study is the largest to report on the relationship between hsTg measurement and long-term prognosis. The present report clearly shows that prognosis generally speaking is excellent, with a very low mortality rate even in patients with distant metastases and nearly nonexistent in patients without distant metastases at diagnosis; mortality rates reported here are on the low end of the spectrum reported in the literature and on par with rates reported in other more recent studies such as, for example, by Hulse et al, 9 Verburg et al 4 and Thies et al 5 The recurrence and mortality rates presented here in patients with a negative stimulated hsTg are low as well. However, when compared with other works such as by Thies et al, 5 where the authors employed a non-hsTg assay with a functional sensitivity of 0.4 ng/ml as calibrated against the reference standard CRM 457, no significant further improvement is offered.…”

Updates on the Management of Thyroid Cancer

“…(3) introducing new categories for T3 tumors -namely T3a ( > 4 cm tumors confined to the thyroid) and T3b (gross extra thyroidal extension into strap muscles); (4) N1 (metastasis to regional LN) disease no longer upstages to stage III or IV in patients over 55 years, all patients remain in stage II; (5) change in LN levels: level VII LNs are now classified as central neck LNs (N1a) along with level VI LNs; and (6) the presence of distant metastases in older patients with DTC is now considered stage IVB as opposed to stage IVC as per the previous classifications [5,12]. The goal of the new staging model is to better reflect the DTC biology and to balance the patients' quality of life and the delivery of cost-effective treatments by down-staging of around 29-38 % of patients [13][14][15][16].…”

“…The 8th edition of AJCC published in 2017 has implemented substantial changes in the staging of DTC. These changes include: (1) increased age cut-off from 45 to 55 years old at diagnosis, stratifying patients with metastatic disease to lower versus higher risk of death based on age; (2) changing the definition of T3 disease eliminating lymph node (LN) metastases and the minimal extra-thyroidal extension reported on histology, as microscopic extra thyroid extension is not an independent factor increasing the risk of death; (3) introducing new categories for T3 tumors – namely T3a (>4 cm tumors confined to the thyroid) and T3b (gross extra thyroidal extension into strap muscles); (4) N1 (metastasis to regional LN) disease no longer upstages to stage III or IV in patients over 55 years, all patients remain in stage II; (5) change in LN levels: level VII LNs are now classified as central neck LNs (N1a) along with level VI LNs; and (6) the presence of distant metastases in older patients with DTC is now considered stage IVB as opposed to stage IVC as per the previous classifications 5 12 . The goal of the new staging model is to better reflect the DTC biology and to balance the patients’ quality of life and the delivery of cost-effective treatments by down-staging of around 29–38% of patients 13 14 15 16 .…”

Impact of TNM® 8th edition on thyroid cancer retrospective staging

“…The number of patients classified as advanced stage (III/IV) fell from 76 (21%) to eight (2%). Of this total, 3/119 (2.5%) patients who were subsequently down-staged died of metastatic disease 7 .…”

“…A patient who was down-staged from stage IV to stage II had ambiguous tumor pathology reported as probable metastatic papillary carcinoma, but possible high-grade squamous cell carcinoma. Patients also died only five months after the initial surgery, suggesting the presence of particularly aggressive disease or pre-existing metastases that were not detected in the initial staging 7 . The present study suggests that not only age, but also evidence of lymph node invasion, are related to the long-term prognosis, emphasizing the importance of the new staging system.…”