The correlation between tumor markers and Ga-68 DOTA-TATE PET/CT findings in patients with advanced medullary thyroid cancer

Medullary thyroid cancer is a rare type of neuroendocrine tumor. Calcitonin (Ctn) and carcinoembryonic antigen (CEA) are used as markers for medullary thyroid cancer. The aim of the study was to evaluate the importance of serum Ctn and CEA levels in predicting total tumor volume. Ga-68 DOTA-TATE PET/CT findings such as whole-body somatostatin receptor-expressing metabolic tumor volume (SSR-E MTV) and total lesion volume (SSR-E TLV) were calculated and correlation analysis was done for tumor markers and whole-body SSR-E MTV and TLV. A total of 28 patients with advanced medullary thyroid cancer were included in this retrospective study. In the correlation analysis, there was a statistically significant positive correlation between Ctn and whole-body SSR-E MTV (rho=0.503 and P=.008). Similarly, significant positive correlation was observed between Ctn and whole-body SSR-E TLV (rho=0.436 and P=.023). There was a significant positive correlation between CEA and whole-body SSR-E MTV (rho=0.584 and P=.007). Also, a positive correlation was observed between CEA and whole-body SSR-E TLV (rho=0.436 and P=.023). These correlations were most marked in patients with Ctn≥152pg/mL and/or both nodal and bone involvement. These results could stimulate clinicians to perform Ga-68 PET for treatment decisions, especially in patients with high CEA and Ctn levels at the time of diagnosis.