VMAT radiation-induced nausea and vomiting in adjuvant breast cancer radiotherapy: The incidental effect of low-dose bath exposure

Background and purpose To investigate the hypothesis on low-dose bath exposure related to radiation-induced nausea and vomiting (RINV) in adjuvant breast volumetric modulated arch therapy (VMAT). Methods and materials A total of 106 consecutive breast cancer patients (pts) treated with adjuvant radiotherapy (RT) with VMAT from January 2013 to May 2016 were evaluated retrospectively. For each pt, a planning CT was reimported and the coeliac plexus and gastroesophageal junction with gastric mouth (GEJCPs) were contoured as a new organ at risk (OAR) in the upper abdominal area. RINV was associated with Dmax and Dmean to GEJCPs. Univariate analysis with χ2, t-test, and Pearson's covariance was used for statistical analysis. Results Of 106 pts, 64% complained of acute RINV according to the Common Terminology Criteria for Adverse Events (CTCAE) version 4.03. RINV was related to Dmax > 10 Gy and Dmean > 3 Gy to GEJCPs (P < 0.005). The radiation breast side and planning target volume (PTV) correlated with RINV. Conclusions RINV in VMAT breast radiotherapy could be a new emerging acute side effect due to a low dose bath to upper abdominal structures such as the GEJCPs. A Dmax < 10 Gy and Dmean < 3 Gy to GEJCPs should be constrained in VMAT planning to minimize RINV risk in breast radiotherapy.