Gastric dose-volume parameters and toxicity in left-sided breast radiotherapy: A single-center retrospective comparison of helical tomotherapy and 3-dimensional field-in-field techniques

During left-sided breast radiotherapy (LSBRT), several organs may be exposed to irradiation and develop treatment-related side effects. Compared with cardiopulmonary toxicity, gastric complications remain relatively under-investigated, although gastrointestinal complications are not uncommon in patients treated with LSBRT. This retrospective single-center study aimed to evaluate the relationship between gastric dose–volume parameters, gastric toxicity, and target volume coverage in patients treated with Helical Tomotherapy (HT) and 3-dimensional field-in-field (3D-FIF) techniques. Sixty-one patients treated with LSBRT were retrospectively analyzed, including 31 treated with HT and 30 with 3D-FIF. Dose–volume histograms were evaluated for target volumes (PTVbreast, PTVsupra, and PTVboost) and the stomach. For target coverage, Dmean, Dmin, Dmax, and D95% parameters were analyzed; for the stomach, Dmean, Dmax, D1cc, D10cc, V5Gy, and V10Gy parameters were analyzed. Reported gastric side effects and radiotherapy fractionation schemes were also evaluated. Toxicities were graded according to the Common Terminology Criteria for Adverse Events (CTCAE v3.0). Comparisons between techniques were performed using appropriate statistical tests (IBM SPSS v27). The primary endpoint was the comparison of gastric dose-volume parameters and gastric toxicity. Patients treated with HT received significantly higher doses for all evaluated stomach dose parameters compared with those treated with 3D-FIF ( P  < .05). The incidence of gastric toxicity was also significantly higher in the HT group ( P  = .013). Notably, patients who developed gastric toxicity had significantly smaller stomach volumes ( P  = .015). Among patients receiving hypofractionated regimens, HT provided significantly higher D95% values for PTV coverage than 3D-FIF ( P  < .05), while no significant difference was observed in mean target doses. HT provided significantly improved target coverage, whereas 3D-FIF was associated with lower gastric dose and reduced gastric toxicity. Individualized technique selection based on patient-specific anatomical variations may help optimize both dosimetric and clinical outcomes.