Andrew Keller

GammaKnife versus VMAT radiosurgery plan quality for many brain metastases

Abstract The purpose of this work was to compare dose distributions between two radiosurgery modalities, single‐isocenter volumetric modulated arc therapy (VMAT), and GammaKnife Perfexion (GK), in the treatment of a large number (≥7) of brain metastases. Twelve patients with 103 brain metastases were analyzed. The median number of targets per patient was 8 (range: 7–14). GK plans were compared to noncoplanar VMAT plans using both 6‐MV flattening filter‐free (FFF) and 10‐MV FFF modes. Parameters analyzed included radiation therapy oncology group conformity index (CI), 12, 6, and 3 Gy isodose volumes (V12 Gy, V6 Gy, V3 Gy), mean and maximum hippocampal dose, and maximum skin dose. There were statistically significant differences in CI (2.5 ± 1.6 vs 1.6 ± 0.8 and 1.7 ± 0.9, P < 0.001, P < 0.001), V12 Gy (2.8 ± 6.1 cc vs 3.0 ± 5.2 cc and 3.1 ± 5.4 cc, P = 0.003, P < 0.001), and V3 Gy (323.0 ± 294.8 cc vs, 880.1 ± 369.1 cc and 937.9 ± vs 361.9 cc, P = 0.005, P = 0.001) between GK versus both 6‐MV FFF and 10‐MV FFF. No significant differences existed for maximum hippocampal or skin doses. In conclusion, highly optimized VMAT produced improved conformity at the expense of a higher V12 Gy and V3 Gy volume when compared with highly optimized GK.

De-escalation of radiotherapy for the treatment of HPV-associated head and neck cancer: A case report and a word of caution

Abstract Background: It has been noted that HPV associated head and neck cancers have an increased responsiveness to radiotherapy. For this reason, strategies at de-escalation are currently being prospectively evaluated. Methods: We report a case of a 58-year-old male who presented with a right neck mass and was diagnosed with HPV associated, p16 positive, cT2N2bM0 tonsillar squamous cell carcinoma. The patient unintentionally received reduced doses of radiation and systemic therapy due to inability to tolerate treatment. Results: The patient was found to have no evidence of disease on 4-month follow-up PET scan and clinical exam. However, several months later, he developed disease recurrence and ultimately required surgical salvage. Conclusions: Until mature results from prospective phase 3 clinical trials are available, we recommend caution in the de-intensification of therapy particularly as current therapy achieves high rates of long term disease control.