Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) is a rare thyroid malignancy originating from parafollicular C-cells. It accounts for 5% of all thyroid carcinomas.

Methods: A retrospective registry-based analysis of demography, clinical manifestation, genetics, management, and outcome of pathologically proven MTC cases presented in a tertiary care hospital in India was done.

Results: Among 71 evaluated cases, the mean age of presentation was 43.63 ± 11.41 years, and 62% were female. The median duration of symptoms was 23 months (IQR 12-34.75 months). The most common presenting complaint was goiter, present in 57 (80.3%) patients. Among the atypical presentation, one patient had ectopic Cushing’s, one with hypertensive crisis in pregnancy due to pheochromocytoma, one patient had chondrosarcoma. Disease was detected incidentally in one patient who had prostatic carcinoma and underwent a PMSA scan, one had associated VHL. Median calcitonin and CEA level at presentation were 1566 pg/ml and 147.5 ng/ml respectively. Among the 25 RET protooncogene mutation assessments, 15 had the mutation positive. Twelve patients had MEN2A and 3 had MEN2B in this cohort one had Erβ positivity. Most of the patients were presented with stage 3 disease and an increasing trend of calcitonin level was observed as the stage of presentation advanced (P= 0.015). Surgery was the primary modality of therapy offered in 95.8% of cases. The mean fall of calcitonin was 86.37 ± 36.11 percent, dependent on the tumor stage at presentation. Twenty-five patients received tyrosine kinase inhibitors as second-line or third-line therapy, 18 received sorafenib, and 10 and 5 patients received lenvatinib, and cabozantinib respectively according to availability. Two patients received PRRT with Lu 177. Thirteen patients had hand-foot syndrome,1 patient had membranoproliferative glomerulonephritis and one had bowel perforation as TKI adverse event. Median progression-free survival (PFS) time was 84 months. Patients with stable disease after the first modality had a PFS of 156 months compared to 72 months in those who had progressive disease at first follow-up (Chi-Square:5.244; P= 0.022).

Discussion: An audit of 10 years of experience of MTC has been reported here. Some of the atypical presentation is documented. A tumour stage and its relation with baseline calcitonin, and responsiveness to TKI along with adverse events and determinants of PFS is also depicted. Hereditary MTC had an earlier age of onset. Limitation of the study being heterogenicity and truncation of data due to the retrospective nature of the study.