A Multicenter Quality Audit Standardizing Esophageal Contouring in Postmastectomy Radiotherapy.

BACKGROUND

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.