Prognostic Value of Metabolic Tumor Volume and Velocity in Predicting Head and Neck Cancer Outcomes

Abstract

Purpose-We previously showed that metabolic tumor volume (MTV) on PET-CT predicts for disease recurrence and death in head and neck cancer (HNC). We hypothesized that increases in MTV over time would correlate with tumor growth and biology, and predict outcome. We sought to examine tumor growth over time in serial pre-treatment PET-CT scans. [2006][2007][2008][2009] 51 patients had two PET-CT scans prior to HNC treatment. MTV was defined as the tumor volume ≥50% of maximum SUV (SUV max ). MTV was calculated for the primary tumor, nodal disease, and composite (primary tumor + nodes). MTV and SUV velocity were defined as the change in MTV or SUV max over time respectively. Cox regression analyses were used to examine correlations between SUV, MTV velocity, and outcome (disease progression and overall survival [OS]). Methods and Materials-FromResults-Median follow-up time was 17.5 months. Median time between PET-CT scans was 3 weeks. Unexpectedly, 51% of cases demonstrated a decrease in SUV max (average −0.1cc/week) and MTV (average −0.3cc/week) over time. Despite the variability in MTV, primary tumor MTV velocity predicted disease progression (hazard ratio [HR] 2.94; p=0.01), and OS (HR 1.85; p=0.03). Conclusions-Primarytumor MTV velocity appears to be a better prognostic indicator of disease progression and survival compared to nodal MTV velocity. However, substantial variability was found in PET-CT biomarkers between serial scans. Caution should be used when integrating PET-CT biomarkers into clinical protocols in HNC.Keywords metabolic tumor volume; functional imaging; head and neck cancers; PETCT

Using FDG-PET to Measure Early Treatment Response in Head and Neck Squamous Cell Carcinoma: Quantifying Intrinsic Variability in Order to Understand Treatment-Induced Change

“…Temporal variability in pretreatment metabolic activity for HNSCC was recently reported by Chu et al 13 in a retrospective study using diagnostic PET/CT and planning PET/CT. They reported serial change as mean composite SUV velocity (SUV max change divided by time in weeks between scans).…”

“…In practice, using such small changes to signify treatment response should be viewed with caution, for it is known that PET scans repeated days or even hours apart without intervening treatment can vary considerably in terms of SUV. [9][10][11][12][13] The significance of this phenomenon is that change observed during the course of treatment must be greater than inherent baseline variability to correctly attribute the observed change to the treatment itself. Intrinsic variability of SUV in the absence of treatment reflects biologic, technical, and observer variation.…”

“…This fluctuation was observed recently in HNSCC in a study that evaluated change in SUV max on pretreatment PET/CT scans that were performed on different scanners. 13 The authors warned about the need to account for variability in PET biomarkers in clinical protocols. Wahl et al, 14 who proposed criteria for the Positron Emission Response Criteria in Solid Tumor (PERCIST) trial, also stated that more studies were needed to address questions concerning the reproducibility of baseline quantitative readings and PET response during the initial phases of treatment.…”

The relationship between tumor volume changes and serial plasma osteopontin detection during radical radiotherapy of non-small-cell lung cancer

“…Assuming that only vital tumor cells are capable of producing and secreting OPN and given that necrotic or largely hypoxic tumor areas have a considerably decreased glucose uptake, decreasing GTV might merely reflect shrinkage of active metabolic tumor volume (MTV). As such, GTV and its changes might be related to tumor kinetics rather than to tumor oxygenation (31,32). Also, post-RT PET contains not only viable tumor volume but also radiation induced tissue injury which has not been shown to influence OPN plasma levels.…”

“…It appears that OPN velocity also provides additional clinical information (35) so that in future studies, OPN plasma levels could be further classified by their velocity (31,35).…”