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The protection of the small intestine and colon from carbon ion particle irradiation by means of Gore-Tex soft tissue patches for patients with pelvic tumors

Reporter: John P. Plastaras, MD, PhD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: October 13, 2006

Presenter: Shigeru Yamada, MD
Affiliation: Division of Radiation Medicine, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan
Other Authors: Tadashi Kamada, Ryusuke Hara, Hirotoshi Kato, Shigeo Yasuda, Masayuki Kano, Shingo Kato, Reiko Ima, Hirohiko Tsujii

Background

• Recurrent pelvic tumors are challenging to treat due to close proximity of bowel that may lie directly adjacent to tumors of the pelvic side-wall or in the sacral hollow
• Carbon ion radiotherapy offers two advantages over photon radiotherapy:
• a higher relative biological effectiveness (RBE)
• no exit dose (similar to protons) as dose is deposited preferentially in a Bragg peak
• Because the dose decreases from a maximum to zero in the span of a few millimeters at the distal edge of a carbon ion treatment beam, the authors surgically placed Gore-Tex spacers between tumors and bowel prior to carbon ion radiation

Material and Methods

• 13 patients with pelvic tumors (8 recurrent rectal cancer, 1 recurrent colon cancer, 2 pelvic sarcomas, and 2 ovarian cancer)
• 8 pelvic side wall
• 3 pre-sacral region
• 2 colorectal anastomosis
• Expanded polytetrafluoroethylene (Gore-Tex soft-tissue patch) was placed surgically between the pelvic tumors and intestines
• Carbon Ion Radiation:
• Mean time between surgery and radiation was 14.5 days (range 10 to 39 days)
• Doses ranged from 52.8 to 73.6 GyE (Gray equivalent)
• 4.2 GyE fractions
• Mean follow-up = 7.2 months (range 2 to 20 months)

Results

• Complications: 2 patients had adhesive ileus after operation and were treated conservatively
• All patients completed the planned radiation treatment
• Toxicity: There were no grade 3 toxicities observed. There were relatively few and mild toxicities
• Local Control:
• 93% at 1 year, 83% at 2 years, 79% at 3 years
• By Dose: 70% with 67.2 GyE, 87% with 70.4 GyE, and 87% with 73.6 GyE
• Survival (3 year):
• By Dose: 36% with 67.2 GyE, 61% with 70.4 GyE, and 81% with 73.6 GyE

Author's Conclusions

• Gore-Tex is a safe and effective implant material to prevent intestinal damage from carbon ion radiation in the treatment of pelvic tumors

Clinical and Scientific Implications

• Insertion of inert material between tumor and organs at risk can provide a buffer for dose fall off distal to target structures when using particle therapy. This principle should in theory also work with proton radiotherapy.
• There appears to be a dose response when treating pelvic tumors with carbon ion radiotherapy, however, it is unclear why patients received various doses in this study
• There was no increased incidence of infection experienced in this series. There was also minimal delay of two weeks starting radiation after the implant was placed