Dr Sher on the Efficacy and Safety of Daily Adaptive Radiotherapy in HNSCC

David Sher, MD, chief, Head and Neck Radiation Oncology Service, vice chair, medical director, Clinical Operations and Quality, Harold C. Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, discusses efficacy outcomes with daily adaptive radiotherapy (DART) with 1-mm planning target volume margins in patients with head and neck squamous cell carcinoma (HNSCC).

The phase 2 DARTBOARD trial (NCT04883281) investigated the feasibility and safety of DART vs standard image-guided radiation therapy (IGRT) in patients with HNSCC. One aspect of this trial evaluated radiation dosimetry, which is the measure of radiation doses that uninvolved tissue receives during radiation treatment, Sher says. As expected, the patients who received DART had improved dosimetry compared with those who received IGRT, because using smaller radiation volumes means treating less tissue, Sher explains. DARTBOARD also showed that reduced radiotherapy doses in the DART arm were associated with meaningful outcomes, Sher notes. For example, the dosimetry of the parotid glands and submandibular glands (SNGs) on both the involved and noninvolved sides of the neck were significantly lower in the DART arm than in the IGRT arm, according to Sher.

Furthermore, DART was associated with fewer acute adverse effects (AEs) vs IGRT, including fewer instances of dermatitis, Sher says. In the DART arm, 8% of patients experienced grade 2 or higher dermatitis vs 31% of patients in the IGRT arm. Patients in the DART arm also experienced a trend towards less mucositis compared with those in the IGRT arm because less of their mouth received radiation therapy, Sher notes.

At 3 months, there was no significant difference in patient-reported outcomes (PROs) between the DART and IGRT arms. This result was expected, as patients were still recovering from the acute AEs associated with their treatment, Sher explains. The primary end point of this trial was 1-year results from the patient-reported Xerostomia Questionnaire. At 6 months, some PRO curves diverged between the 2 arms, and trends favored faster recovery in the DART arm, Sher says.

Notably, investigators observed a statistically significant improvement in EORTC sticky saliva scores in the DART arm vs the IGRT arm, according to Sher. This result was expected based on the dosimetry improvements seen in the SMGs in the DART arm, Sher explains. These data need to mature to 1 year, when further PRO stabilization may occur, Sher concludes.