Simultaneous Modulated Accelerated Radiotherapy (SMART) with Dysphagia Aspiration-Related Structures (DARS) Sparing: Do We Have a Role for Dose Condensation in Locally Advanced Head and Neck Cancer

Introduction Concurrent chemotherapy integrated with intensity-modulated radiotherapy (IMRT) is the standard of care for locally advanced head and neck cancer. Simultaneous integrated boost technique has allowed differential doses to primary and normal structures permitting significant toxicity reduction. The current study explores the feasibility of the simultaneous modulated accelerated radiotherapy (SMART) technique to enhance cytoreduction and explore the possibility of dose intensification with radiobiologically targeted treatment condensation. Methods Thirty patients were randomized in an open-labeled study to receive concurrent chemoradiation of 60 Gy in 25 fractions with “SMART” technique or 70 Gy in 35 fractions using conventional intensity-modulated radiotherapy simultaneous integrated boost “IMRT SIB.” The primary endpoints included comparative volumetric cytoreduction between the study and control arm assessed during the course of treatment and final response evaluation. Secondary endpoints involved the assessment of acute toxicity parameters for xerostomia, mucositis, dysphagia, and fatigue. Results The “SMART” study arm showed comparable volumetric cytoreduction to the conventional “IMRT SIB” arm at midtreatment (p-value = 0.225) as well as toward completion (p-value = 0.476). The study arm did observe 94.4% cytoreduction of tumor volume compared with 88.05% in the conventional arm at the time of response evaluation. In spite of treatment condensation, there was no significant increase in toxicity with “SMART.” There was no difference in the frequency or duration of grade 3 mucositis in the “SMART” arm in spite of intensification (p-value = 0.728). In the “SMART” arm, there was a favorable reduction in the duration of grade ⅔ dysphagia; 2.8 weeks versus 4.6 weeks (p-value = 0.002). Even though the xerostomia was comparable in frequency and intensity, the total duration of xerostomia was 50% less (p-value = 0.001). Conclusions The “SMART” technique provides a radiobiologically sound, effective, and safe protocol that has the potential to improve the treatment of locally advanced head and neck cancer. The good tolerability and toxicity profile in the study arm is encouraging and facilitates further research.