Implementation and Early Clinical Results Utilizing Cs-131 Permanent Interstitial Implants for Gynecologic Malignancies

Gynecol Oncol. 2014 May;133(2):268-73. doi: 10.1016/j.ygyno.2014.02.015. Epub 2014 Feb 17.

Abstract

Objective: Permanent interstitial brachytherapy is an ideal yet underutilized treatment modality for accessible, small volume gynecological malignancies. We present early clinical results utilizing a new permanent isotope, Cs-131.

Methods: A retrospective review was performed evaluating patients treated with Cs-131 permanent interstitial radiation at our institution from July 2011 through June 2013. Doses were most commonly prescribed and calculated to a depth of 5mm using Paterson-Parker planar implant rules for Au-198. This activity was converted to air-kerma strength (U). A conversion factor of 1.1 was applied based on RBE calculations, clinical observation and experience.

Results: 14 patients were identified among whom 17 Cs-131 implants were performed. Seven patients were implanted as sole therapy, and a median dose of 50 Gy was delivered. Ten implants were performed as boost within a more extensive radiation treatment plan. In these patients, a median implant dose of 27.5 Gy was used and the median total dose delivered in combination was 78.25 Gy. After a median follow up of 12 months, the actuarial local control rate was 84.4%. A very low level of grade 1-3 reactions was observed with no fistula formations or other severe side effects.

Conclusions: Permanent interstitial brachytherapy with Cs-131 was well tolerated with favorable early results compared to other series. Cs-131 has multiple favorable properties, including minimal radiation exposure to treating staff, and should be considered as a therapeutic option in appropriately selected patients. A methodology for dose prescription, calculation of radioactivity required and distribution of the isotope is also presented.

Keywords: Brachytherapy; Cs-131; Gynecologic cancer; Interstitial radiation; Radiation implant; Re-irradiation.

Publication types

  • Observational Study

MeSH terms

  • Adenocarcinoma / radiotherapy*
  • Adenocarcinoma, Clear Cell / radiotherapy
  • Adult
  • Aged
  • Aged, 80 and over
  • Brachytherapy / methods*
  • Carcinoma, Papillary / radiotherapy*
  • Carcinoma, Squamous Cell / radiotherapy*
  • Cesium Radioisotopes / therapeutic use*
  • Cohort Studies
  • Disease-Free Survival
  • Endometrial Neoplasms / radiotherapy
  • Fallopian Tube Neoplasms / radiotherapy
  • Female
  • Genital Neoplasms, Female / radiotherapy*
  • Humans
  • Melanoma / radiotherapy*
  • Middle Aged
  • Neoplasm Recurrence, Local / radiotherapy*
  • Retrospective Studies
  • Treatment Outcome
  • Uterine Cervical Neoplasms / radiotherapy*
  • Vaginal Neoplasms / radiotherapy

Substances

  • Cesium Radioisotopes

Supplementary concepts

  • Glassy cell carcinoma of the cervix