Tumor Volume Doubling Time of Less Than One Year is Associated with a Higher Risk of Death from Medullary Thyroid Cancer

Abstract Context Tumor volume doubling time (TVDT) is emerging as a useful tool in predicting oncologic outcomes. There is limited data on the prognostic role of TVDT in metastatic medullary thyroid cancer (MTC). Purpose The goal of this study was to assess the value of TVDT in predicting disease-specific survival (DSS) in patients with hereditary and sporadic MTC. Methods This was an Institutional Review Board-approved cohort study including patients with metastatic MTC having at least 3 consecutive imaging studies. TVDT of up to the five largest lesions per organ was calculated using a standardized formula. The association between TVDT and DSS was analyzed using Kaplan-Meier survival curves. Cox proportional regression model was used to account for confounding factors. Results The study sample consisted of 51 patients presenting with 286 metastatic lesions measured with 457 scans during the follow-up of 51 (IQR 25-102) months. Median age was 19 years (IQR 15-41), 53% female patients. Cumulative volumes of all metastatic lesions and proportion of patients with TVDT of <1 year were higher in patients with sporadic as compared with hereditary MTC (p<0.01). Factors independently associated with shorter DSS were TVDT of <1 year based on 3 initial and 3 last scans as well as lung, brain and prostate as the organs with the fastest growing tumor. TVDT based on 2-dimentional and 3-dimentional measurements showed strong correlation (r=0.94, p<0.05). Conclusions Three baseline and three most recent scans preceding follow-up visit enable calculation of TVDT and can be used as predictors of mortality from MTC.