A Novel Form of Breast Intraoperative Radiation Therapy With CT-Guided High-Dose-Rate Brachytherapy: Results of a Prospective Phase 1 Clinical Trial

• Published in: International journal of radiation oncology, biology, physics Vol. 96; no. 1; pp. 46 - 54
• Main Authors: Showalter, Shayna L., MD, Petroni, Gina, PhD, Trifiletti, Daniel M., MD, Libby, Bruce, PhD, Schroen, Anneke T., MD, MPH, Brenin, David R., MD, Dalal, Parchayi, BA, Smolkin, Mark, MS, Reardon, Kelli A., MD, Showalter, Timothy N., MD, MPH
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2016
• Subjects: Aged; BRACHYTHERAPY; Brachytherapy - adverse effects; Brachytherapy - methods; Breast Neoplasms - diagnostic imaging; Breast Neoplasms - radiotherapy; CLINICAL TRIALS; Combined Modality Therapy - adverse effects; Combined Modality Therapy - methods; COMPUTERIZED TOMOGRAPHY; CONSUMER PRODUCTS; CT-GUIDED RADIOTHERAPY; Dose Fractionation; DOSE RATES; DOSIMETRY; Feasibility Studies; Female; GY RANGE 10-100; Hematology, Oncology and Palliative Medicine; Humans; Intraoperative Care - methods; MAMMARY GLANDS; Mastectomy - methods; Middle Aged; NEOPLASMS; PATIENTS; RADIATION DOSES; Radiation Injuries - etiology; Radiation Injuries - prevention & control; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; Radiotherapy Dosage; Radiotherapy, Image-Guided - methods; STANDARD OF LIVING; Tomography, X-Ray Computed - methods; TOXICITY; Treatment Outcome
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2016.04.035

Purpose Existing intraoperative radiation therapy (IORT) techniques are criticized for the lack of image guided treatment planning and energy deposition with, at times, poor resultant dosimetry and low radiation dose. We pioneered a novel method of IORT that incorporates customized, computed tomography (CT)-based treatment planning and high-dose-rate (HDR) brachytherapy to overcome these drawbacks: CT-HDR-IORT. Methods and Materials A phase 1 study was conducted to demonstrate the feasibility and safety of CT-HDR-IORT. Eligibility criteria included age ≥50 years, invasive or in situ breast cancer, tumor size <3 cm, and N0 disease. Patients were eligible before or within 30 days of breast-conserving surgery (BCS). BCS was performed, and a multilumen balloon catheter was placed. CT images were obtained, a customized HDR brachytherapy plan was created, and a dose of 12.5 Gy was delivered to 1-cm depth from the balloon surface. The catheter was removed, and the skin was closed. The primary endpoints were feasibility and acute toxicity. Feasibility was defined as IORT treatment interval (time from CT acquisition until IORT completion) ≤90 minutes. The secondary endpoints included dosimetry, cosmetic outcome, quality of life, and late toxicity. Results Twenty-eight patients were enrolled. The 6-month follow-up assessments were completed by 93% of enrollees. The median IORT treatment interval was 67.2 minutes (range, 50-108 minutes). The treatment met feasibility criteria in 26 women (93%). The dosimetric goals were met in 22 patients (79%). There were no Radiation Therapy Oncology Group grade 3+ toxicities; 6 patients (21%) experienced grade 2 events. Most patients (93%) had good/excellent cosmetic outcomes at the last follow-up visit. Conclusions CT-HDR-IORT is feasible and safe. This promising approach for a conformal, image-based, higher-dose breast IORT is being evaluated in a phase 2 trial.