Session Item

Nausea is a common symptom in patients irradiated for brain tumors The dorsal vagal complex (DVC) located in the brainstem (BS) has been identified as the center of nausea and vomiting. The objective of our study was to determine a threshold dose at the DVC inducing nausea or vomiting in patients irradiated for benign brain tumors.

Between December 2017 and January 2021, 102 consecutive patients were irradiated for benign brain tumors, with normofractionated VMAT technique, without chemotherapy, at the Bordeaux University Hospital,. DVC delineation was performed on T1 sequences with gadolinium injection using the reference atlas [Beddok et al. RO 2019]. Quality control of delineation was performed for the first 10 patients by 5-radiation oncologists  with Kappa index analysis. Nausea symptoms and anti-nausea treatments were collected at each weekly consultation during the radiotherapy treatment. Dosimetric criteria were analyzed for DVC, CT, and brain, and compared between groups of patients with and without nausea

Among 102 patients, 68 were women, median age 61.5 years. The tumors treated were mainly meningiomas (80%) and neurinomas (17%). Regarding delineation quality control, Kappa index was 0.67 for a volume of 0.13cm3, reflecting a correct agreement on DVC contours comparable to Beddok et al [RO 2019]. The median dose was 54Gy [48.6-57.6Gy]. Out of 102 patients, 40 (39.2%) had nausea requiring anti-nausea treatment for 23 (57.5%) patients Women accounted for 77% in the nausea group and 60% in the non nausea group (p=0.06). In the group of patients with nausea, all volumes (VxGy) of DVC and TC irradiated were significantly higher for all parameters collected (V10-V20-V30-V40, mean, median dose) except V50 compared to asymptomatic patients. There was no significant difference for the brain dosimetric criteria. For patients without and with nausea, the mean DVC dose was 8.9Gy versus 21.6Gy (p<10^-4), respectively, and the mean brainstem dose was 16.9Gy versus 27.1Gy (p<10^-3). DVC mean dose is more predictive of nausea than brainstem dose. Below a DVC mean dose of 10Gy, 22% of patients are at risk of radiation induced nausea, compared to 60% above 10Gy (p=0.0001).

The mean DVC dose is significantly associated with radiation-induced nausea. A dose constraint below 10Gy to decrease the incidence of radiation-induced nausea needs to be validated by a prospective study.