Three-Dimensional Printing in Breast Radiation Therapy: A Scoping Review of the Literature.

introductionTissue equivalent bolus is used to increase dose to skin and superficial tissue in adjuvant breast or chest wall radiation therapy. Three-dimensional (3D) printed bolus offers a customised conformal device and potential for improved anatomic conformity and dose distribution.

methodsA literature search was defined as per PRISMA guidelines for scoping review. Inclusion criteria were determined using PICO guidelines. The parameters of interest, including year, journal, study type, intervention details, clinical sample size and pre-clinical case numbers, were extracted from each article. The reported outcomes, such as dosimetry, anatomic conformity, dose to organs at risk and toxicity data were recorded.

resultsThirteen publications were reviewed, six studies were pre-clinical and seven were clinical. Ten were performed in the post-mastectomy setting and utilised polylactic acid (PLA) bolus. Overall, most studies reported marginal improvement in dosimetry, anatomic conformity, organ at risk dosimetry and toxicity with 3D printed bolus. However, sample sizes utilised were small and study design was variable with unusual choices of comparator arm and introduction of other variables.

conclusionThree-dimensional printed bolus is an emerging technology in radiation oncology. Most available data in the setting of breast radiation therapy is positive, though interpretation of results is difficult given the small sample sizes and variable study design. Further investigations in larger cohorts in a clinical setting is warranted.