Role of Diffusion Weighted Magnetic Resonance Imaging in Oral Cancer in Predicting Response to Neoadjuvant Chemotherapy.

To downstage the locally advanced or inoperable oral cancer, neoadjuvant chemotherapy (NACT) is required. Early response assessment to chemoradiotherapy is needed to avoid unnecessary treatment in patients who are nonresponders. We conducted a prospective study to evaluate the role of diffusion weighted imaging (DWI) in predicting the response after NACT in locally advanced carcinoma of oral cavity. After ethical approval, A total of 19 patients were enrolled for the study. MRI were performed using T1W, T2W, T1W post contrast and DW images (b values b0, 100, 500, and 1000 sec/mm²). Timing of scans were fixed as- pretreatment, 2 weeks after the initiation of first cycle of NACT after 3rd cycle of NACT. ADC values of the tumors were assessed in each scan. The mean age of the population was 46 years and majority were males. ​​In our study, most patients had buccal mucosal cancer (13 patients). Patients with stable disease and progressive disease were labelled as non-responders, whereas patients with partial response and complete response were designated as responders. In our study, 11 patients were responders and 8 patients were non-responders. There was a significant difference between the baseline ADC values of responders and non-responders (p value = 0. 017). The increase in the mean absolute ADC and nADC values at the early time point was greater in the responders than the non-responders, and the difference was statistically significant (p values = 0.05 and 0.04 respectively). There was a significant difference between the baseline ADC values of responders and non-responders (p value = 0. 017). ADC values of diffusion weighted MRI can be utilized to predict the response to neoadjuvant chemotherapy in squamous cell carcinoma of oral cavity as masses with high baseline ADC values are less likely to respond to chemotherapy.