Differentiated Thyroid Cancer in Adolescents: Single Center Experience and Considerations for Surgical Management and Radioiodine Treatment

Objective: Differentiated thyroid cancer (DTC) in adolescents rare but with a favorable outcome, despite higher rates of cervical lymph node and pulmonary metastasis compared to adults. The aim of this study was to critically evaluate treatment of adolescents with DTC at a single center. Methods: Patients receiving postoperative radioiodine treatment (RAIT) for DTC between 2005 and 2020 at our institution were screened to identify adolescents according to the World Health Organization definition (10-19 years of age). Demographics, clinico-pathological characteristics, treatment and outcome were analyzed. Results: Among 1,897 DTC patients, 23 (1.3%) were adolescents with a median (range) age of 16 (10-18) years. The female to male ratio was 3.6:1. Sixty percent had classic papillary thyroid cancer, with follicular variant in 40%, which was higher than previously reported (15-25%) for this age group. pT-status was pT1 in 9 (39.2%), pT2 in 8 (34.8%), pT3 in 3 (13%) and pT4 in 3 (13%) patients. In 19 (82.6%) patients, central lymphadenectomy was performed and metastasis was seen in 57%. All patients received RAIT with initial activities of 1.2 (n=1, 4.3%), 2 (n=12, 52.2%) or 3.7 GBq (n=10, 43.5%). Eighteen (78.2%) patients were free of biochemical and radiologic disease at a median follow-up of 60.7 months. Second-line surgery for lymph node relapse was necessary in 3 (13%) cases. There was one disease-associated death. Conclusion: Despite high rates of metastasis, most patients were cured, and second-line surgery was rarely required. Further prospective studies are needed to determine whether less aggressive surgical management or omitting adjuvant RAIT are feasible in patients with limited stages at diagnosis.

Occurrence of High Microsatellite-Instability/Mismatch Repair Deficiency in Nearly 2,000 Human Adenocarcinomas of the Gastrointestinal Tract, Pancreas, and Bile Ducts: A Study From a Large German Comprehensive Cancer Center.

INTRODUCTION: Knowledge of the high microsatellite-instability (MSI-H)/mismatch repair deficiency (MMRd) status is of increasing interest for personalized neoadjuvant or adjuvant therapy planning. Only a few studies are available on MSI-H distribution in the Northern European Caucasian patient population. In this study, we focused on a large cohort of tumors of the upper gastrointestinal tract. MATERIALS AND METHODS: Surgical material from a total of 1,965 patients was analyzed for MSI-H/MMRd status (including 1,267 carcinomas of the esophagus or stomach). All tumors were analyzed with an internationally recommended immunohistochemical panel consisting of four antibodies (MLH1, MSH2, PMS2, and MSH6). The results were molecularly objectified. RESULTS: Adenocarcinomas with MSI-H/MMRd were detected with the following distribution: esophagus (1.4%), stomach (8.3%), small intestine (18.2%), large intestine (8.5%), intrahepatic bile ducts (1.9%), and pancreas (0%). In case of gastric tumors with MSI-H/MMRd, neoadjuvant therapy did not influence the prognosis of patients (p = 0.94). Within all tumor entities with MSI-H/MMRd, patients with a UICC stage 4 were also represented. In this advanced stage, 11.7% of patients with MSS tumors were diagnosed compared to 0.5% of patients with MSI-H tumors relative to the entire tumor collective. DISCUSSION: In this study, the proportion of MSI-H/MMRd tumors in the stomach is smaller than would have been expected in knowledge of the data published by TCGA or AGRC. Negative prognostic effects regarding MSI-H status and neoadjuvant therapy as described by the MAGIC study group were not seen in our cohort. The extent to which the MSI-H/MMRd status should be known for neoadjuvant therapy planning must be clarified in prospective studies in the future. At present, there is no convincing data to dispense the neoadjuvant therapy for gastric carcinoma. Due to the very convincing, positive data regarding the response rates of MSI-H tumors to treatment with PD1/PD-L1 inhibitors, every metastatic carcinoma of the gastrointestinal tract should be tested for its MSI-H status.