Gastrointestinal Cancer

SS 17 - GI 3 - Colon/Rectum/Anus

131 - International Multi-institutional Study of Intraoperative Radiation Therapy for Recurrent Gastrointestinal Tumors

Monday, October 22
5:05 PM - 5:15 PM
Location: Room 214 C/D

International Multi-institutional Study of Intraoperative Radiation Therapy for Recurrent Gastrointestinal Tumors
E. H. Balagamwala1, C. A. Reddy1, C. M. Leyrer1, S. Potemin2, M. D. Kolar1, W. Polkowski3, E. Sperk4, F. Wenz5, S. R. Amarnath6, T. Hull7, S. Chalikonda7, and S. Cherian1; 1Department of Radiation Oncology, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, 2Department of Colorectal Surgery of the Regional Oncological Center of Krasnodar, Krasnodar, Russian Federation, 3Department of Surgical Oncology, Medical University of Lublin, Lublin, Poland, 4Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany, 5Department of Radiation Oncology, University Medical Center Mannheim, University of Heidelberg, Mannheim, Germany, 6Cleveland Clinic Taussig Comprehensve Cancer Center, Cleveland, OH, 7Cleveland Clinic, Cleveland, OH

Purpose/Objective(s): Patients with locally advanced or recurrent gastrointestinal (GI) cancers in a previously irradiated field may benefit from intraoperative radiation therapy (IORT). Furthermore, IORT can be utilized as a boost prior to planned external beam radiation therapy when there is concern for positive margins. We performed an international multi-institutional study to evaluate the outcomes of IORT for GI cancers in North America and Europe.

Materials/Methods: We performed an IRB-approved retrospective review of all patients treated with IORT for recurrent GI cancer at large tertiary hospitals in the US, Russia, Poland and Germany. All patients were treated using a photon IORT system. The clinical and treatment records were reviewed and detailed information on initial cancer diagnosis, prior radiation therapy (RT), IORT, outcomes including local failure (LF), regional failure, distant failure as well as toxicities after IORT were collected. When IORT dose was prescribed to depth, it was normalized to surface for analysis. Statistical analyses were done using Kaplan-Meier analysis and Cox proportional hazards regression.

Results: A total of 297 patients who underwent abdominopelvic IORT for recurrent GI cancers were included in this study. The median age at IORT was 64 years (range, 24 – 86) and the median follow up is 11.9 months. The majority of patients had adenocarcinoma (98.3%) whereas only 1.7% of patients had squamous cell carcinoma. 66 (22.2%) patients had fixation of tumor at time of surgery and 66 (22.2%) patients had positive margins. Half the patients had received prior external beam RT. The median prior RT dose was 5040 cGy (range, 2500 – 6600 cGy) in 28 fractions (range, 5 – 37). Median tumor size was 4 cm (0.1 – 11 cm). Median IORT dose (normalized to surface) was 1500 cGy (range, 600 – 3300 cGy) and the median applicator diameter was 5 cm (range, 2 – 5). At last follow-up, 254 (85.5%) patients were alive. After IORT, 29 patients (9.8%) developed a local recurrence and 7 patients (2.4%) developed a regional recurrence. Univariate analysis demonstrated that positive margin (HR 2.6, p=0.01), prior RT (2.8, p=0.01), smaller tumor size (HR 0.7, p<0.01), tumor fixation (HR 5.5, p<0.1), dose prescription to depth (HR 3.9, p<0.01) were associated with a higher risk for local recurrence. On multivariable analysis, tumor fixation (HR 6.8, p<0.01), dose prescription to depth (HR 2.9, p=0.03) and smaller tumor size (HR 0.6, p<0.01) continued to be associated with development of local recurrence. Most common toxicity was hydronephrosis (4.4%), followed by infection (2.7%) and GI fistula (1%).

Conclusion: This large international, multi-institutional study shows that IORT provides excellent local control for recurrent GI cancers. We also show that tumor fixation and dose prescription to depth is associated with a higher risk for development of local failure. Risk for toxicity after IORT was low overall. Our analysis suggests that IORT should be utilized in patients at high risk of having a local recurrence.

Author Disclosure: E.H. Balagamwala: Employee; Cleveland Clinic. C.A. Reddy: Stipend; Red Journal. C.M. Leyrer: None. S. Potemin: None. W. Polkowski: None. E. Sperk: None. F. Wenz: None. S.R. Amarnath: None.

Ehsan Balagamwala, MD

Disclosure:
Employment
Cleveland Clinic: Resident Physician: Employee, Staff Physician: Employee

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