Sacral Neuromodulation (SNM) With InterStimTM for Bowel Dysfunction Following Surgery for Rectal Cancers With Sphincter Preservation

Sacral Neuromodulation (SNM) With InterStimTM for Bowel Dysfunction Following Surgery for Rectal Cancers With Sphincter Preservation

Randomized Crossover Study of the Efficacy of Sacral Neuromodulation (SNM) With InterStimTM for Bowel Dysfunction Following Surgery for Rectal Cancers With Sphincter Preservation

The purpose of this study is to evaluate whether a medical device/implant (InterStimTM) will help patients to have more normal bowel movements. The InterStimTM device is a neuromodulating device. Neuromodulation is a way of changing the activity of the nervous system by using electrical stimulation. InterStimTM is FDA approved to help people who have a hard time controlling their bowl movements. This is called fecal incontinence.The device is placed near a nerve root in the lower back. It works in a manner similar to a pacemaker by releasing electrical stimulation that triggers the S3 nerve root. When being placed, it is initially tested to make sure it will work using a temporary wire and then, if successful, the device is permanently implanted.

This is a single-blind randomized crossover study. After providing written informed consent, eligible patients will undergo an initial stimulation procedure with a temporary lead (Step 1 Wire Stimulation). The simulation is performed to determine efficacy of the device before a permanent implant is placed. This stimulation takes place over a period of 7-14 days (+/-3 days). Because this procedure is done in the OR, this window of time allows for optimization of the device and coordination of operating room schedules. This is the time period that has been used in prior trials. Typically bowel improvement has been seen relatively quickly, so the range should not affect our assessment of BFI. After the Wire Implantation has occurred, patients will be evaluated over the next 7-14 days (+/- 3 days) and will complete the BFI questionnaire. If BFI improvement is < than or = to 4 points the wire will be removed in the operating room, the patient will be offered standard of care, and the patient will no longer be part of the study. Based on our prior data, we would like to give as many patients as possible the opportunity for enrollment and as a result we have chosen a 4 point BFI change as minimum criteria for response. Our group has seen that a change in the BFI around 5-6 is clinically significant, but we will lower this threshold slightly. If a patient's BFI improves by ≥ 4 points, the patient will proceed to the randomized phase (Step 2-Implantation) of the study. Patients who proceed to Step 2- Implantation, they will return to the operating room for the implantation of the permanent device. While in the operating room they will be randomly assigned to either having the device stimulation on (Group A) or device stimulation off (Group B) for first 4 weeks (+/-3 days). Patients will return to clinic 2 weeks later to cross over to the other arm (Step 3-Crossover) and the device stimulation will be set to on or off. Patients will come back to clinic within 7 days (+/- 7 days) after Crossover for device check and optimization.

The device will be set to stimulate for 4 weeks, then off for two weeks, and then the device will be on but will not stimulate for 4 weeks.

The device will be on but will not stimulate for 4 weeks, then off for two weeks, and then the device will be set to stimulate for 4 weeks.

Bowel function will be assessed by using the MSK BFI. We have chosen the BFI because it is widely endorsed to assess the clinical problem that these patients have. The BFI is a 19 item instrument to which a patient responds using a 5-point Likert scale, ranging from Always to Never.

QOL and urinary continence will be assessed at the start of the study (Baseline), after initial stimulation (Step 1-Wire Stimulation), and at each point in the crossover trial (Step 2-Implantation and Step 3-Crossover). Graphical displays will be used to explore data distributions of all secondary outcome measures over time. We assume no period effect and will evaluate the treatment effect using the paired t-test (and a repeated measures ANOVA to include other covariates in the model) for each of our main outcome measures, EuroQOL5, FIQOL, LARS and Bladder function. We will test for period effect to confirm this.

Inclusion Criteria: History of rectal cancer or neoplastic polyp (i.e. intramucosal carcinoma, carcinoma in situ) BFI score must meet at least one of the below criteria: Total BFI < 50 Dietary subscale < 11 Frequency subscale < 19 Urgency subscale < 12 English speaking Patients ≥18 years old. age Sphincter-preserving surgery and ≥ 12 months after restoration of bowel continuity Exclusion Criteria: Locally recurrent or metastatic disease Immune suppressive medication Seizure disorder Prior sacral/lower spinal surgery Congenital Spinal defect/Paraplegia Rectal prolapse IBD/Crohn's Pregnancy Active anal/rectal abscess Pacemaker or other electronic implanted device Immediate need for MRI At the time of the wire stimulation procedure, patients will be excluded if the surgeon is unable to place the temporary stimulating lead Inability to commit to local follow up for device management.