Bath and Shower Effects in the Rat Parotid Gland Explain Increased Relative Risk of Parotid Gland Dysfunction After Intensity-Modulated Radiotherapy

van Luijk, Peter; Faber, Hette; Schippers, Jacobus M.; Brandenburg, Sytze; Langendijk, Johannes A.; Meertens, Harm; Coppes, Robert P.

doi:10.1016/j.ijrobp.2009.03.039

« Previous Next »International Journal of Radiation Oncology * Biology * Physics
Volume 74, Issue 4 , Pages 1002-1005, 15 July 2009

Bath and Shower Effects in the Rat Parotid Gland Explain Increased Relative Risk of Parotid Gland Dysfunction After Intensity-Modulated Radiotherapy

Peter van Luijk, Ph.D.
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
- Reprint requests to: Peter van Luijk, Ph.D., P.O. Box 30001, 9700 RB, Groningen, The Netherlands. Tel: +31-50-3611739; Fax: +31-50-3611692
Hette Faber
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
Jacobus M. Schippers, Ph.D.
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
- Accelerator Department, Paul Scherrer Institut, Villigen, Switzerland
Sytze Brandenburg, Ph.D.
- Kernfysisch Versneller Instituut, University of Groningen, Groningen, the Netherlands
Johannes A. Langendijk, M.D., Ph.D.
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
Harm Meertens, Ph.D.
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
Robert P. Coppes, Ph.D.
- Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
- Department of Cell Biology, Section Radiation and Stress Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands

Received 5 March 2009; received in revised form 13 March 2009; accepted 15 March 2009.

Purpose

To assess in a rat model whether adding a subtolerance dose in a region adjacent to a high-dose irradiated subvolume of the parotid gland influences its response (bath-and-shower effect).

Methods and Materials

Irradiation of the whole, cranial 50%, and/or the caudal 50% of the parotid glands of Wistar rats was performed using 150-MeV protons. To determine suitable (i.e., subtolerance) dose levels for a bath-dose, both whole parotid glands were irradiated with 5 to 25 Gy. Subsequently groups of Wistar rats received 30 Gy to the caudal 50% (shower) and 0 to 10 Gy to the cranial 50% (bath) of both parotid glands. Stimulated saliva flow rate (function) was measured before and up to 240 days after irradiation.

Results

Irradiation of both glands up to a dose of 10 Gy did not result in late loss of function and is thus regarded subtolerance. Addition of a dose bath of 1 to 10 Gy to a high-dose in the caudal 50% of the glands resulted in enhanced function loss.

Conclusion

Similar to the spinal cord, the parotid gland demonstrates a bath and shower effect, which may explain the less-than-expected sparing of function after IMRT.

Radiotherapy, Normal tissue damage, Parotid gland, Xerostomia, Dose-volume effects