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Dose Delivered to the Lumbosacral Plexus From High-Dose-Rate Brachytherapy for Cervical Cancer
  1. Dominique Rash, MD*,
  2. Blythe Durbin-Johnson, PhD,
  3. Jihoon Lim, BA*,
  4. Sonja Dieterich, PhD*,
  5. Adam Huddleston, MD*,
  6. Sun Yi, MD and
  7. Jyoti Mayadev, MD*
  1. *Department of Radiation Oncology, University of California Davis, Comprehensive Cancer Center, Sacramento, CA;
  2. Division of Biostatistics, Department of Public Health Sciences, University of California Davis School of Medicine, Sacramento, CA; and
  3. Department of Radiation Oncology, University of Arizona, Tucson, AZ.
  1. Address correspondence and reprint requests to Jyoti Mayadev, MD, Department of Radiation Oncology, University of California Davis, Comprehensive Cancer Center, Sacramento, CA 95817. E-mail:


Objective To calculate dose delivered to the lumbosacral plexus (LSP) with cervical brachytherapy using 3-dimensional imaging, and to compare this with the position of the tandem in the pelvis using bony landmarks. We also report long-term LSP toxicity outcomes.

Methods and Materials Treatment planning images from 55 patients treated with tandem and ring brachytherapy from October 2009 through November 2012 were reviewed. The LSP was contoured on planning computed tomographic scans to calculate dose received. Lumbosacral plexus dose was studied as a function of tandem distance from the sacrum and pubic symphysis (STratio) measured on digitally reconstructed radiographs. Patient and implant characteristics were included as covariates on LSP dose. Clinical follow up on LSP toxicity was recorded.

Results Patients were prescribed 550 to 700 cGy using computed tomography–based imaged-guided brachytherapy for 4 to 5 fractions. The maximum dose to 2 cc (D2cc) of LSP ranged from 44 to 287 cGy per implant. The median D2cc was 118 cGy, corresponding to 18% of prescription dose. Patients with an STratio less than 0.33 (closer to the sacrum) and at least 0.33 had median LSP doses of 138 and 98 cGy, respectively. Lumbosacral plexus dose did not change significantly with body mass index, uterus position, or tumor stage. Two patients reported symptoms of peripheral neuropathy, with a median follow-up of 14.7 months.

Conclusions The mean D2cc per fraction to the LSP is roughly 20% of the prescribed high dose-rate and varies with the position of the tandem from the sacrum. The dose threshold for radiation-induced neuropathy of the LSP remains undefined.

  • Gynecologic brachytherapy
  • Cervical cancer
  • Lumbosacral plexus

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  • Presented at the 2013 meeting of the American Society for Radiation Oncology, Atlanta, GA; September 22–25, 2013.

  • The project described was supported in part by the National Center for Advancing Translational Sciences, National Institutes of Health, through Grant No. UL1 TR000002.

  • The authors declare no conflicts of interest.