Intraoperative high-dose-rate brachytherapy using dose painting technique: evaluation of safety and preliminary clinical outcomes.

PURPOSE

Intraoperative radiation therapy (IORT) allows delivery of tumoricidal doses of radiation to areas of potential residual microscopic disease while minimizing doses to normal tissues. IORT using high-dose-rate (HDR) brachytherapy allows dose modulation and delivery of concomitant boosts to high-risk areas. This study describes a novel technique of HDR-IORT with dose painting (DP) (HDR-IORT-DP) and evaluates the clinical outcomes.

METHODS AND MATERIALS

Sixteen patients with recurrent cancers received HDR-IORT-DP at the time of radical resection. Of these patients, 13 had colorectal cancer, 2 had head and neck cancer, and 1 had a gynecologic malignancy. All received external beam radiation previously. Negative margin (R0) was obtained in 12 patients (75%) and microscopically positive margins (R1) in 4 patients (25%).

RESULTS

The median total target and boost area were 45 and 8.5cm(2), and HDR-IORT and boost dose were 1500 and 1750cGy, respectively. Median followup was 14.9 months. The 2-year local control and overall survival were 80% and 20%, respectively. Eleven patients (69%) developed distant metastasis and were deceased at the time of the last followup. A total of 13 patients (19%) developed Grade 3 toxicity related to HDR-IORT; no grade 4+ toxicities were observed.

CONCLUSIONS

HDR-IORT-DP technique is feasible, safe, and allows for dose escalation in locally advanced or recurrent previously irradiated tumors. To our knowledge, this is the first clinical report on HDR-IORT-DP. Further studies are warranted to evaluate efficacy in a larger patient cohort. Local control was encouraging in our patients.