Intraoperative radiation therapy with 50 kV x-rays: A multi-institutional review.

This report covers clinical implementation of a low kV intraoperative radiation therapy (IORT) program with the INTRABEAM® System (Carl Zeiss Meditec AG, Jena, Germany). Based on collective user experience from eight institutions, we discuss best methods of INTRABEAM quality assurance (QA) tests, commissioning measurements, clinical workflow, treatment planning, and potential avenues for research. The guide provides pertinent background information and clinical justification for IORT. It describes the INTRABEAM system and commissioning measurements along with a TG100 risk management analysis to ensure safety and accuracy of the IORT program. Following safety checks, dosimetry measurements are performed for verification of field flatness and symmetry, x-ray output, and depth dose. Also discussed are dose linearity checks, beam isotropy, ion chamber measurements, calibration protocols, and in-vivo dosimetry with optically stimulated luminescence dosimeters OSLDs, and radiochromic film. Emphasis is placed on the importance of routine QA procedures (daily, monthly, and annual) performed at regular intervals for a successful IORT program. For safe and accurate dose delivery, tests of important components of IORT clinical workflow are emphasized, such as, dose prescription, pre-treatment QA, treatment setup, safety checks, radiation surveys, and independent checks of delivered dose. Challenges associated with in-vivo dose measurements are discussed, along with special treatment procedures and shielding requirements. The importance of treatment planning in IORT is reviewed with reference to a Monte Carlo-based commercial treatment planning system highlighting its main features and limitations. The report concludes with suggested topics for research including CT-based image-guided treatment planning and improved prescription dose accuracy. We hope that this multi-institutional report will serve as a guidance document on the clinical implementation and use of INTRABEAM IORT.

Targeted Intraoperative Radiotherapy During Breast-conserving Surgery for Breast Cancer in Patients After Implant Augmentation.

BACKGROUND/AIM: Targeted intraoperative radiotherapy (TARGIT IORT) is an option during breast-conserving surgery (BCS). No data have yet been published regarding the safety of TARGIT IORT with implants in situ. TARGIT IORT is an attractive option in this context because of the risk of capsular fibrosis following external beam radiotherapy (EBRT) in such patients. PATIENTS AND METHODS: We are reporting a retrospective analysis of 16 patients who received TARGIT IORT during BCS for early breast cancer after previous implant-based breast augmentation. TARGIT IORT was performed using the Intrabeam™method. RESULTS: Follow-up varied from 98 to 5 months. There were no procedure-related complications. One patient developed local recurrence after 36 months of follow-up. Among the remaining patients (15/16), no breast-cancer-related events occurred. CONCLUSION: This series of patients with TARGIT IORT during BCS after implant-based breast augmentation revealed no safety concerns and gives some confidence in discussing this option with selected patients.

TARGIT-R (Retrospective): North American Experience with Intraoperative Radiation Using Low-Kilovoltage X-Rays for Breast Cancer.

BACKGROUND: Single-dose intraoperative radiotherapy (IORT) is an emerging treatment for women with early stage breast cancer. The objective of this study was to define the frequency of IORT use, patient selection, and outcomes of patients treated in North America. METHODS: A multi-institutional retrospective registry was created, and 19 institutions using low-kilovoltage IORT for the treatment of breast cancer entered data on patients treated at their institution before July 31, 2013. Patient selection, IORT treatment details, complications, and recurrences were analyzed. RESULTS: From 2007 to July 31, 2013, a total of 935 women were identified and treated with lumpectomy and IORT. A total of 822 patients had at least 6 months' follow-up documented and were included in the analysis. The number of IORT cases performed increased significantly over time (p < 0.001). The median patient age was 66.8 years. Most patients had disease that was <2 cm in size (90 %) and was estrogen positive (91 %); most patients had invasive ductal cancer (68 %). Of those who had a sentinel lymph node procedure performed, 89 % had negative sentinel lymph nodes. The types of IORT performed were primary IORT in 79 %, secondary IORT in 7 %, or planned boost in 14 %. Complications were low. At a median follow-up of 23.3 months, crude in-breast recurrence was 2.3 % for all patients treated. CONCLUSIONS: IORT use for the treatment of breast cancer is significantly increasing in North America, and physicians are selecting low-risk patients for this treatment option. Low complication and local recurrence rates support IORT as a treatment option for selected women with early stage breast cancer.

An update of the phase III trial comparing whole pelvic to prostate only radiotherapy and neoadjuvant to adjuvant total androgen suppression: updated analysis of RTOG 94-13, with emphasis on unexpected hormone/radiation interactions.

PURPOSE: This trial was designed to test the hypothesis that total androgen suppression and whole pelvic radiotherapy (WPRT) followed by a prostate boost improves progression-free survival (PFS) by > or =10% compared with total androgen suppression and prostate only RT (PORT). This trial was also designed to test the hypothesis that neoadjuvant hormonal therapy (NHT) followed by concurrent total androgen suppression and RT improves PFS compared with RT followed by adjuvant hormonal therapy (AHT) by > or =10%. METHODS AND MATERIALS: Patients eligible for the study included those with clinically localized adenocarcinoma of the prostate and an elevated prostate-specific antigen level of <100 ng/mL. Patients were stratified by T stage, prostate-specific antigen level, and Gleason score and were required to have an estimated risk of lymph node involvement of >15%. RESULTS: The difference in overall survival for the four arms was statistically significant (p = 0.027). However, no statistically significant differences were found in PFS or overall survival between NHT vs. AHT and WPRT compared with PORT. A trend towards a difference was found in PFS (p = 0.065) in favor of the WPRT + NHT arm compared with the PORT + NHT and WPRT + AHT arms. CONCLUSIONS: Unexpected interactions appear to exist between the timing of hormonal therapy and radiation field size for this patient population. Four Phase III trials have demonstrated better outcomes when NHT was combined with RT compared with RT alone. The Radiation Therapy Oncology Group 9413 trial results have demonstrated that when NHT is used in conjunction with RT, WPRT yields a better PFS than does PORT. It also showed that when NHT + WPRT results in better overall survival than does WPRT + short-term AHT. Additional studies are warranted to determine whether the failure to demonstrate an advantage for NHT + WPRT compared with PORT + AHT is chance or, more likely, reflects a previously unrecognized biologic phenomenon.