3D-Printed Bolus-Assisted Radiotherapy for Converting Unresectable Breast Cancer with a Breast Prosthesis into a...

Background: The use of conventional boluses in recurrent breast cancer often fails to conform to irregular surfaces, leading to air gaps and suboptimal dose distribution. We present a clinical experience involving a 3D-printed conformal bolus for a patient with gross recurrence and breast prosthesis invasion-a complex scenario where the treatment goal was surgical conversion. This report aims to generate hypotheses regarding the utility of customized boluses in facilitating the resection of initially unresectable tumors in the presence of reconstructive hardware. Case Presentation: A 58-year-old female with a history of breast cancer and prosthesis reconstruction presented with a rapid chest wall recurrence in 2018. The tumor invaded the overlying skin and the underlying prosthesis, rendering it unresectable. The patient received intensive salvage radiotherapy using Volumetric Modulated Arc Therapy (VMAT) with a dose-escalation regimen and a customized 1 cm 3D-printed bolus. While daily IGRT/CBCT and in vivo dosimetry were not available to definitively quantify the air gap reduction, the technical application of the bolus aimed to optimize surface dose coverage. Two months post-treatment, significant tumor regression was observed, allowing for the successful surgical removal of both the tumor and the prosthesis. Conclusions: To our knowledge, this case illustrates a specialized application of 3D-printed boluses in complex salvage scenarios. Following treatment, the patient experienced improved quality of life through pain reduction and reduced dressing frequency. Although the dramatic tumor response likely reflects the overall intensity of the radiotherapy regimen, our experience suggests that a 3D-printed bolus is a physically plausible tool to aid in achieving local control and facilitating surgical intervention. Further prospective studies are required to isolate the specific dosimetric advantages of this technology over conventional methods.