Description

Hypothesis The study's hypothesis is that vibration therapy, using the stimulation parameters found in the pilot study, will have a beneficial effect on erectile function, orgasm disturbances, penile shortening, and urinary incontinence, both generally and in connection with sexual activity.

Methods The study is conducted as a randomized, controlled non-blinded study. Men undergoing a nerve-sparing operation for prostate cancer are divided into two groups. A total of 100 men will be included in the study. In case a surgery cannot be performed with nerve preservation or if a participant experiences a recurrence of their prostate cancer requiring additional treatment, the participant will be withdrawn from the study.

Randomization and Treatment Overall, we will investigate the effect of vibration stimulation on erectile function, orgasm disturbances, penile shortening, and urinary incontinence, both generally and in connection with sexual activity. In accordance with the hypotheses, this study will offer vibration therapy for a longer duration than before. Both the vibration group and the control group will be offered fixed post-operative treatment with phosphodiesterase-5-inhibitors as per the standard protocol. Participants will be randomized into the two groups through drawing lots for either vibration or no vibration. Randomization will be done using block randomization via a computer-generated list. The "Ferticare 2.0" vibrator (produced by the company Reflexonic LLC, Leesburg VA, USA) will be used in the study, which is a modernized version of the previously used vibrator and is sold as a sexual aid in Denmark. It is safety-approved with European CE marking as a "household appliance" and is sold as a sexual aid in Denmark. Men in the vibration group will be instructed on the stimulation before their prostate surgery. Subsequently, participants will be able to perform the vibration therapy themselves at home. In both groups, participants must undergo a standard pelvic floor training program, and both groups will be offered fixed PDE-5 inhibitor treatment in the form of daily tadalafil, 5 mg, as the standard treatment for erectile difficulties after the operation. In the vibration group, daily stimulation will be directed towards the frenulum for a minimum of 5 minutes, with an amplitude of 1 mm and a frequency of 90 Hz, as found in the pilot study. Participants will start getting used to the vibration 1-4 weeks before the surgery and resume it within 14 days after the operation. The daily stimulation will continue for a period of 9 months, along with the standard treatment. After these 9 months, men in both groups will stop taking tadalafil during a 4-week wash-out period, after which their spontaneous sexual function will be evaluated. This is necessary due to the well-known positive effect of the medication. In comparison to the standard treatment in the department, offering vibration to half of the participants is an addition. Regarding pelvic floor training and medication for erectile difficulties for all study participants, the current standard is to offer these to all men who have undergone nerve-sparing radical prostatectomy. This will proceed as usual, and the only deviation from usual practice is ensuring that the medication offer is consistent for all participants. The mentioned 4-week period without tablet treatment (wash-out) is necessary to assess spontaneous erections. This is a deviation from the normal standard, as such a wash-out is not conducted for patients who do not participate in research, but it will not affect the actual erectile function of the participants in either group.

Data Collection

Standard investigations related to prostate cancer will be conducted according to normal guidelines, with the registration of:

• Pre-operative PSA
• Clinical and pathological tumor stage
• Gleason score
• Prostate size
• Degree of nerve preservation during the surgery
• Any complications during the surgery
• Resection margin status (positive or negative)
• PSA measurements at 3, 6, and 12 months after the operation. This information will be obtained from the patient's medical records by the scientific staff after the study participants have given their consent to participate. After providing consent, the study organizers, sponsor, sponsor's representatives, and any regulatory authorities will have direct access to obtain information from the patient's medical records, including electronic records, for the purpose of reviewing information about the research participant's health, as necessary for conducting the research project and for monitoring, including self-monitoring, quality control, and oversight, as they are obligated to perform.

Since potential participants are screened and informed about the project during their visits to the outpatient clinic (see the section on Recruitment of Study Participants and Informed Consent), there is no need to obtain information from the patient's medical records before consent is given. At this stage, the research team only receives the name, social security number, and contact information for patients who have expressed interest in the project.

Additional examinations are carried out before the surgery and at follow-ups at 3 months, 6 months, and 10 months (equivalent to the end of the wash-out period) after the surgery, with the registration of the following for all participants in both the vibration group and the control group:

Before the surgery and at follow-ups:

• Validated symptom questionnaires for erectile function (IIEF-EF and EHS)
• Specific questionnaire about orgasm disturbances, penile shortening, and urinary incontinence during sexual activity.
• Validated symptom questionnaire for incontinence symptoms (ICIQ-SF)
• 24-hour pad weighing test (only at follow-ups for men who are not fully continent)

Additional registrations at follow-ups:

• Registration of PSA recurrence after the surgery and noting any additional treatment
• Any side effects of vibration and standard treatment