Endocrine Abstracts

Introduction: Although medullary thyroid cancer (MTC) constitutes 2–4% of all thyroid cancers, it is associated with higher mortality compared to differentiated thyroid carcinomas. Here we present long term clinical results of medullary carcinoma patients’ follow-up in our center.

Methods and results: MTC was detected in 27 (3.73%) patients of 850 thyroid cancer cases who were followed-up between 2004 and 2020 at the Marmara University School of Medicine, Endocrinology and Metabolic Diseases Department. The mean age at diagnosis was 47.7 ± 14. The female/male (20/7) ratio was 2.8. The mean follow-up was 7.29 ± 4.9 years. In 16 (59.2%) patients, the diagnosis was compatible with medullary thyroid carcinoma in fine-needle aspiration biopsy, the remaining patients were diagnosed after thyroidectomy. The diagnosis was made by biopsy from the supraclavicular lymph node in 2 patients (7.4%), one had no nodule on the thyroid. None of the patients had distant metastases at the time of diagnosis. Neck lymph node metastasis was detected in 8 patients (29.6%) at the time of diagnosis. Relapse occurred in a median of 2 years (min-max: 1–14) after the first surgery in 3 patients (11.1%).

MTC was detected on the right lobe in 12 patients (44.4%), on the left lobe in 13 patients (48.1%), and bilaterally in 2 patients (7.4%). The meantumor diameter was 1.9 ± 1.3 cm. Papillary thyroid microcarcinoma was detected in the contralateral thyroid lobe in 3 patients. The preoperative median calcitonin level was 363.5 ng/l (min-max:5–5655). Median postoperative calcitonin level was 3.3 ng/l (min-max:0.5–871), CEA level was 4.49 ng/ml (min-max: 0.45–14.6).RET mutation was heterozygous positive in 2 patients (7.4%).

Preoperative calcitonin level (P = 0.206), presence of invasion (P = 0.516) and tumor diameter (P = 0.581)was not associated with response rate;on the other hand postoperative calcitonin level (P = 0.0045) was the only effective factor on remission rate.

In the last visit, 7 (25.9%) patients had a structural incomplete response, and 3 patients (11.1%) had a biochemical incomplete response. 17 (59.3%) patients were in remission, none of the patients died of MTC or another cause.

Conclusion: We observed a higher recurrence rate compared to the literature. In previous studies, 10-year survival was associated with age, disease stage, and postoperative calcitonin levels. Postoperative calcitonin level was the only factor associated with survival in our patients.

Keywords: medullary thyroid carcinoma, calcitonin, life expectancy.