Adjuvant high dose rate brachytherapy in the management of soft tissue sarcoma - A dose-toxicity analysis

Objectives: Although brachytherapy has been used in the management of soft tissue sarcoma for decades, there is little published data regarding dose and toxicity. We performed an interim analysis of our high dose-rate experience to establish dosing guidelines. Methods: We analyzed our first 12 soft tissue sarcoma patients treated with high dose-rate brachytherapy as tumor bed boost (in conjunction with beam therapy), seeking an association between treatment factors and wound-healing complications. In the process of our analysis, we devised a dosimetric method to retrospectively quantify delivered dose. Our findings were used to formulate dosing guidelines; the first 5 cases treated along these guidelines are also presented. Results: Despite the small number of cases, we were able to demonstrate a correlation (P < 0.01) between wound healing and brachytherapy dose (fractional or total biologically equivalent dose). We found no relationship between wound healing and patient age, diabetes, width of excised skin, cross-sectional area of implant, sequencing of therapy, or surgery-to-brachytherapy interval. Conclusion: There appears to be a relationship between dose and disturbed wound healing that should be respected to avoid unnecessary toxicity. An objective technique for defining target volume and quantifying dose is proposed for meaningful analysis of dose/effect relationships.