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

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.