Correlation between tumor voxel dose response matrix and tumor biomarker profile in patients with head and neck...

We have developed a novel imaging analysis procedure that is highly predictive of local failure after chemoradiation in head and neck cancer. In this study we investigated whether any pretreatment biomarkers correlated with key imaging parameters.

Pretreatment biopsy material was available for 28 patients entered into an institutional trial of adaptive radiotherapy in which FDG-PET images were collected weekly during treatment. The biopsies were immunohistochemically stained for CD44, EGFR, GLUT1, ALDH1, Ki-67 and p53 and quantified using image analysis. Expression levels were correlated with previously derived imaging parameters, the pretreatment SUV_max and the dose response matrix (DRM).

The different parameters of the SUV_max and DRM did not correlate with each other. We observed a positive and highly significant (p = 0.0088) correlation between CD44 expression and volume of tumor with a DRM greater than 0.8. We found no correlation between any DRM parameter and GLUT1, p53, Ki-67 and EGFR or ALDH1. GLUT1 expression did correlate with the maximum SUV₀ and the volume of tumor with an SUV₀ greater than 20.

The pretreatment SUV_max and DRM are independent imaging parameters that combine to predict local recurrence. The significant correlation between CD44 expression, a known cancer stem cell (CSC) marker, and volume of tumor with a DRM greater than 0.8 is consistent with concept that specific foci of cells are responsible for tumor recurrence and that CSCs may be randomly distributed in tumors in specific niches. Dose painting these small areas may lead to improved tumor control.