Preserved sacral neuromodulation efficacy despite prior pelvic radiation in cancer survivors
DOI: Pending DOI
Synopsis
Pelvic radiation can affect neural and tissue integrity involved in bladder and bowel function, raising concern for reduced response to sacral neuromodulation (SNM). We evaluated SNM outcomes in pelvic cancer survivors by radiation status in a two-institution retrospective cohort (n=36). Trial success (≥50% improvement) occurred in 86%, with no difference between radiated and non-radiated patients (84% vs 88%). Sustained benefit remained high at 6 weeks (90%) and long-term follow-up (74%). Device-related reoperation occurred in 39%, with no difference in durability. Despite expected radiation-associated tissue and potential neural injury, SNM outcomes were preserved. These findings suggest that prior radiation does not meaningfully impair the response to sacral neuromodulation
Background
Pelvic malignancy treatments frequently result in lower urinary tract symptoms and fecal incontinence due to structural and neurological injury. Radiation therapy, in particular, induces fibrosis, microvascular damage, and neural injury within the pelvic plexus, potentially disrupting afferent and efferent signaling required for continence.1-3 These changes raise concern that neuromodulation therapies, which depend on neural signaling pathways, may be less effective in this population.
Sacral neuromodulation (SNM) modulates sacral reflex circuits to restore bladder and bowel function and is widely used for refractory overactive bladder, urinary retention, and fecal incontinence.4 However, outcomes in pelvic cancer survivors—especially those with prior radiation—remain poorly defined, with existing studies limited to small cohorts and predominantly fecal incontinence populations.5-7
We evaluated whether prior pelvic radiation impacts SNM trial success, durability, and sustained symptom improvement in a multi-institutional cohort.
Methods
We conducted a retrospective cohort study of pelvic cancer survivors undergoing staged SNM between 2012 and 2023 at two academic centers. Patients were included if they underwent Stage I testing for refractory urinary or bowel dysfunction following treatment for pelvic malignancy. Patients were stratified by prior pelvic radiation exposure.
The primary outcome was trial success, defined as progression from Stage I to Stage II implantation following ≥50% symptom improvement. Secondary outcomes included early sustained benefit (~6 weeks), long-term sustained benefit at last follow-up, and device durability measured as time to first reoperation (revision or explant).
Continuous variables were summarized as median (IQR) and compared using Wilcoxon rank-sum tests. Categorical variables were compared using Fisher’s exact tests. Device durability was assessed using Kaplan–Meier analysis and log-rank testing. Given sample size limitations, multivariable modeling was not performed.
Results
Thirty-six patients were included, of whom 19 (53%) had prior radiation. Median age was 69 years (IQR 51–74), and 67% were female. Indications included overactive bladder (53%), urgency incontinence (19%), urinary retention (19%), and fecal incontinence (28%).
Trial success occurred in 31/36 patients (86%), with no difference by radiation status (84% RT vs 88% no RT, p > 0.9). Among implanted patients, early sustained benefit at 6 weeks was observed in 28/31 (90%), and long-term sustained benefit in 20/27 (74%), with no significant differences between groups (all p > 0.1).
Device-related reoperation occurred in 12/31 patients (39%) due to pain, infection, or loss of efficacy. Kaplan–Meier analysis demonstrated no significant difference in freedom from reoperation between groups (log-rank p = 0.16), although a non-significant trend toward reduced durability in radiated patients was observed at later time points (Fig. 1).
Notably, despite higher rates of prior chemotherapy (68% vs 6%, p = 0.006) and lower rates of prior surgery (53% vs 88%, p = 0.03) in the radiation group, functional outcomes remained comparable across all measured endpoints.
Discussion
Despite concerns that radiation-induced neural injury may impair neuromodulation response, SNM efficacy was comparable across radiated and non-radiated patients. These findings suggest that prior radiation does not meaningfully impair functional response to sacral neuromodulation.
Our results extend prior work in fecal incontinence cohorts by including both urinary and bowel indications and directly comparing radiation exposure. Outcomes were consistent with reported ranges in idiopathic SNM populations, suggesting that cancer-related dysfunction may remain amenable to neuromodulation.
These findings have direct clinical implications for patient selection and counseling, supporting the use of SNM in pelvic cancer survivors who might otherwise be excluded due to concerns about prior radiation.
Disclosures
Nothing to disclose by any authors.
References
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