Main Session
Sep
29
PQA 06 - Genitourinary Cancer, Gynecological Cancer, and Health Care Access and Engagement
Presenter(s)
Mihir Karande, MD - Fox Chase Cancer Center, Philadelphia, PA
M. Karande1, L. Camejo2, G. Souflis3, L. Levin3, W. Li4, E. M. Horwitz5, H. N. Yankey5, M. A. Hallman5, P. L. Lee6, A. Correa4, L. Zhang4, J. Fredette7, and J. K. Wong5; 1Fox Chase Cancer Center, Philadelphia, PA, United States, 2Lewis Katz School of Medicine at Temple University, Philadelphia, PA, 3Temple University Hospital System, Philadelphia, PA, 4Fox Chase Cancer Center, Philadelphia, PA, 5Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, 6Department of Radiation Oncology, Mass General Brigham, Harvard Medical School, Boston, MA, 7Department of Biostatistics and Bioinformatics, Fox Chase Cancer Center, Philadelphia, PA
Purpose/Objective(s):
Rectal wall infiltration (RWI), a complication of hydrogel spacer insertion, is associated with severe rectal injury and infectious sequelae. This study aims to evaluate the incidence and MRI grade of RWI after hydrogel spacer insertion in men receiving prostate stereotactic body radiotherapy (SBRT) and assess associations between clinical symptoms, biopsy approach (transrectal vs. transperineal), and rectal toxicity.
Materials/Methods:
This single-institution, retrospective study evaluated men treated with hydrogel rectal spacer placement and prostate SBRT between 2018 and 2024. Three radiologists assessed post–spacer simulation MRIs and assigned an RWI score of 0 (no abnormality), 1 (rectal wall signal abnormality), 2 (partial-thickness gel infiltration), or 3 (full-thickness rectal wall breach). Other endpoints were symptomatic RWI (defined as gel in stool, pelvic pain, or infectious signs) and presence of grade 2-3 events (defined as diarrhea, rectal bleeding, and proctitis). Demographic and clinical variables were summarized and compared by RWI abnormality, using means and standard deviations for continuous variables and frequencies and proportions for categorical variables, with Wilcoxon rank sum test or Fisher’s exact tests.
Results:
There were a total of 136 eligible men with a mean age of 68. Among the cohort, 79 patients (58.1%) had RWI 0, 22 (16.2%) had RWI 1, 30 (22.1%) had RWI 2, and 5 (3.7%) had RWI 3. Symptomatic RWI occurred in 3 men (2.2%), all with radiographic abnormalities (2 had RWI score of 1, 1 had a RWI score of 2) and transrectal biopsies, with one developing urosepsis (0.7%). Grade 2-3 events were seen in 13 men (9.6%), of whom 4 had radiographic RWI. Serious spacer-related complications were infrequent (2 men, 1.5%). No Grade 4-5 events (life-threatening) were observed. The presence of RWI radiographically was not significantly associated with symptomatic RWI (5.3% with vs. 0% without, p=0.071) or grade 2-3 events (7.0% vs. 11.4%, p=0.557). Biopsy approach was not associated with radiographic RWI (p=0.374).
Conclusion:
In this cohort, radiographic RWI after hydrogel spacer placement was observed, but symptomatic RWI, clinically significant toxicity, and serious spacer-related complications were rare. Biopsy approach and baseline clinical variables were not associated with RWI. Most MRI abnormalities did not translate into clinically meaningful events. These findings are consistent with existing literature in supporting the safety of hydrogel spacer placement in the prostate.