Placement of an absorbable rectal hydrogel spacer in patients undergoing low-dose-rate brachytherapy with palladium-103 Journal Article
| Authors: | Taggar, A. S.; Charas, T.; Cohen, G. N.; Boonyawan, K.; Kollmeier, M.; McBride, S.; Mathur, N.; Damato, A. L.; Zelefsky, M. J. |
| Article Title: | Placement of an absorbable rectal hydrogel spacer in patients undergoing low-dose-rate brachytherapy with palladium-103 |
| Abstract: | Purpose: Rates of rectal toxicity after low-dose-rate (LDR) brachytherapy for prostate cancer are dependent on rectal dose, which is associated with rectal distance from prostate and implanted seeds. Placement of a hydrogel spacer between the prostate and rectum has proven to reduce the volume of the rectum exposed to higher radiation dose levels in the setting of external beam radiotherapy. We present our findings with placing a rectal hydrogel spacer in patients following LDR brachytherapy, and we further assess the impact of this placement on dosimetry and acute rectal toxicity. Methods and Materials: Between January 2016 and April 2017, 74 patients had placement of a hydrogel spacer, immediately following a Pd-103 seed-implant procedure. Brachytherapy was delivered as follows: as a monotherapy to 26 (35%) patients; as part of planned combination therapy with external beam radiotherapy to 40 (54%) patients; or as a salvage monotherapy to eight (11%) patients. Postoperative MRI was used to assess separation achieved with rectal spacer. Acute toxicity was assessed retrospectively using Radiation Oncology Therapy Group radiation toxicity grading system. Rectal dosimetry was compared with a consecutive cohort of 136 patients treated with seed implantation at our institution without a spacer, using a 2-tailed paired Student's t test (p < 0.05 for statistical significance). Results: On average, 11.2-mm (SD 3.3) separation was achieved between the prostate and the rectum. The resultant mean rectal volume receiving 100% of prescribed dose (V100%), dose to 1 cc of rectum (D1cc), and dose to 2 cc of rectum (D2cc) were 0 (SD 0.05 cc), 25.3% (SD 12.7), and 20.5% (SD 9.9), respectively. All rectal dosimetric parameters improved significantly for the cohort with spacer placement as compared with the nonspacer cohort. Mean prostate volume, prostate V100 and dose to 90% of gland (D90) were 29.3 cc (SD 12.4), 94.0% (SD 3.81), and 112.4% (SD 12.0), respectively. Urethral D20, D5cc, and D1cc were 122.0% (SD 17.27), 133.8% (SD 22.8), and 144.0% (SD 25.4), respectively. After completing all treatments, at the time of first the followup, 7 patients reported acute rectal toxicity—6 experiencing Grade 1 rectal discomfort and 1 (with preexisting hemorrhoids) experiencing Grade 1 bleeding. Conclusions: Injection of rectal spacer is feasible in the post-LDR brachytherapy setting and reduces dose to the rectum with minimal toxicity. Prostate and urethral dosimetries do not appear to be affected by the placement of a spacer. Further studies with long-term followup are warranted to assess the impact on reduction of late rectal toxicity. © 2017 American Brachytherapy Society |
| Keywords: | aged; major clinical study; salvage therapy; diarrhea; monotherapy; treatment planning; nuclear magnetic resonance imaging; follow up; radiotherapy dosage; cohort analysis; retrospective study; prostate cancer; gastrointestinal toxicity; radiation oncology; dosimetry; brachytherapy; external beam radiotherapy; acute toxicity; personal experience; urine retention; urethra; palladium 103; rectum hemorrhage; rectal toxicity; prostate volume; proctitis; hydrogel; low-dose-rate brachytherapy; human; male; priority journal; article; rectal spacer; rectal discomfort |
| Journal Title: | Brachytherapy |
| Volume: | 17 |
| Issue: | 2 |
| ISSN: | 1538-4721 |
| Publisher: | Elsevier Science, Inc. |
| Date Published: | 2018-03-01 |
| Start Page: | 251 |
| End Page: | 258 |
| Language: | English |
| DOI: | 10.1016/j.brachy.2017.11.006 |
| PROVIDER: | scopus |
| PUBMED: | 29241706 |
| PMCID: | PMC7463274 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 2 April 2018 -- Source: Scopus |
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