Background: Oropharyngeal squamous cell carcinoma (OPSCC) not associated with the human papillomavirus (HPV) have a poor prognosis compared to their HPV-associated counterpart. In literature diffusion-weighted imaging (DWI) shows great potential as a biomarker for treatment response in HPV-associates OPSCC. For this study the possibility of using DWI parameters as biomarker for treatment response during treatment of HPV-negative OPSCC is investigated. Tumor size and shrinkage have also been investigated.
Methods: In this study sixteen patients with HPV-negative OPSCC who underwent (chemo-)radiotherapy have been included. All are current and/or former smokers. At two time point an DWI-MRI scan took place, before and 2 weeks into treatment. The mean apparent diffusion coefficient (ADC) and Non-Gaussian Intravoxel Incoherent Motion Imaging (NG-IVIM) parameters based on the gross tumor volume (GTV) have been calculated. The parameters and differences in parameters have been compared between patients that responded well to treatment and patients with progressive disease.
Results: At pre- and midtreatment no significant differences have been found between the Complete Response (CR) and Progressive Disease(PD) patient groups. Diffusion coefficient D showed a significant change between pre- and midtreatment, with an increase for PD and decrease for CR. When comparing the residual region to the region that had disappeared after two weeks based on pretreatment data significant differences have been found in ADC, D and f for CR, as well as f for PD.
Conclusion: Changes in D during treatment have shown to be a significant predictor for treatment response. However this study is limited by a small patient group and more research with larger cohorts and additional biomarkers is needed to develop reliable clinical decision-making tools.