Tumor grade as a novel predictor of outcomes in medullary thyroid cancer

Abstract

The recent development of the International Medullary Thyroid Cancer Grading System (IMTCGS) provided clinicians with a tool to predict for disease outcomes after undergoing resection based on histologic features. However, its impact on the clinical management of patients is still under investigation. Utilizing the IMTCGS, we evaluated the association of grade with postoperative surveillance markers. High-grade tumors, when compared to low-grade, had a significantly more rapid calcitonin doubling time with a vast majority of high-grade patients having doubling times <2 years. While these findings reaffirmed the poor recurrence and mortality outcomes observed in high-grade patients, we found that high-grade patients with rapid calcitonin doubling times were particularly at risk for poor local control and survival outcomes.These findings demonstrate the importance of close clinical follow-up of patients with high-grade disease and further support the determination tumor grade and calcitonin doubling times in MTC patients after resection. In addition, the study supports the use of MTC grading as an important variable for future management of MTC patients. This could lay the foundation for better understanding of neuroendocrine carcinomas of the breast.