Tumor Volume Doubling Time of Less Than 1 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 are limited data on the prognostic role of TVDT in metastatic medullary thyroid cancer (MTC).

Objective: 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 5 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 < .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-dimensional and 3-dimensional measurements showed strong correlation (r = 0.94, P < .05).

Conclusion: Measurements from 3 baseline and 3 most recent scans preceding follow-up visit enable calculation of TVDT and can be used as predictors of mortality from MTC.