A Multicenter Quality Audit Standardizing Esophageal Contouring in Postmastectomy Radiotherapy

Postmastectomy radiotherapy (PMRT) delivered with volumetric modulated arc therapy (VMAT) often results in higher esophageal doses than 3D techniques. Recent dose-toxicity studies recommend limiting the esophageal mean dose (D mean ) to less than 11 Gy, based on contours drawn from the cricoid to the carina. In contrast, our network's auto-segmentation delineates the entire esophagus, potentially underestimating dose to clinically relevant upper esophageal segments. This audit evaluated current dose-reporting practices and their implications for toxicity.

A multicenter retrospective audit of 43 consecutive PMRT cases (March 10 to May 5, 2025) across 8 centers was performed. All sites recontoured the esophagus using the cricoid-to-carina definition and submitted paired dosimetric values. One center reported grade 2 esophagitis rates in a separate clinical cohort before and after implementing the standardized contouring approach.

Standardized contouring increased the networkwide mean esophageal dose from 6.1 Gy to 11.7 Gy. The median D mean increased from 5.7 Gy to 9.6 Gy ( P  < .001). Sixteen of 42 evaluable patients (38.1%) exceeded the 11-Gy benchmark. In the separate cohort, grade 2 esophagitis decreased from 6 of 7 pre-standard operating procedure (SOP) to 0 of 7 post SOP ( P  = .004).

Standardizing esophageal contouring improves dose accuracy and is associated with reduced symptomatic esophagitis, supporting routine use of cricoid-to-carina contours to enhance toxicity risk assessment in PMRT.