Surgery is a major treatment modality for prostate cancer  and has been hypothesised to reduce mortality more than other treatments for localised prostate cancer . However, the risks of surgery are known to include erectile dysfunction  even when nerve-sparing approaches are used . Long-lasting sexual and urinary difficulties are the most common and troubling side-effects following radical prostatectomy  alongside loss of libido, ejaculatory dysfunction, orgasmic dysfunction and penile shortening . Even at 24 months post-operatively, most men have not returned to their baseline measure of sexual function prior to surgery . These side-effects can be distressing for men and their partners due to the impact on psychological well-being and couple intimacy [8–11].
Many men affected by prostate cancer and erectile dysfunction experience symptoms of anxiety and depression [12, 13], with reduced quality of life directly associated with urinary and sexual body-image changes that occur after surgery . Partners of these men also experience considerable psychological distress [9, 15–17], with anxiety and depression often reported at higher levels for partners than for patients [18, 19]. The difficulties experienced after surgery can also impact on the couple relationship itself; for instance, erectile dysfunction is associated with reduced wellbeing [20, 21] and lower levels of dyadic adjustment in the first year after surgery .
Prostate cancer has been described as a ‘relationship disease’  and it has been established that couples affected by prostate cancer often have significant unmet psychosexual supportive care needs around sexual recovery and rehabilitation [24, 25]. With such evidence of the impact of sexual dysfunction on relationships, there has been increasing interest in the development of couple-based psychosocial interventions that aim to improve wellbeing and relationship quality. Couple-based interventions have been effective in reducing psychological distress  and facilitating healthy communication [27, 28]. Sexual rehabilitation therapy has been particularly helpful in increasing use of erectile dysfunction medications  and re-establishing a sexual relationship [30, 31].
Evidence therefore exists to support the efficacy of couple-based interventions for reducing psychological distress, enhancing couple communication and improving relationship functioning among couples affected by cancer . Interventions for couples affected by prostate cancer have targeted sexual functioning , relationship functioning , or combined both aspects [19, 28, 29, 34, 35]. Reviewed systematically, the overall effectiveness of such interventions remains inconclusive , although manualised face-to-face interventions that address the connection between sexual difficulties and relationship variables have shown improvements in sexual functioning, including erectile function. Chisholm et al.  conclude that the evidence remains weak due to methodological limitations, such as small sample sizes and ineffective outcome measures, while longer-term gains in functioning have been limited.
Of particular note, interventions have not been successful in improving both relationship and sexual functioning . Consequently, it would be beneficial to devise an intervention framework that has a lasting impact on sexual and emotional aspects of the couple relationship. Studies suggest that understanding family-of-origin relationships may be important in supporting sexual functioning in marriage , and that to address sexual issues it is critical to support the relationship more generally . Consequently, an approach which is family-relational and psychosexual combines key elements of a potentially fruitful intervention.
The current study offers a family-relational-psychosexual approach to supporting the couple, by combining family systems principles with elements of sex therapy. Combining these approaches enables the intervention to address broader relational issues that impact specific problems around sex and intimacy. The intervention therefore has the potential for long-term benefits to participants, as the wider context of prostate cancer and couple dynamics are a focus. It will develop a new way of supporting couples that combines family systems principles with elements of sex therapy to enhance intimacy and reduce distress. A family systems approach is based on an understanding that the family/relational context influences couple dynamics, which consequently impact on relational and psychosexual outcomes. The treatment model adopts a comprehensive approach to couple support, addressing communication and relationships within the family context, to address broader relational issues in which specific problems around sex and intimacy will be located.
The primary aim of the study is to determine whether a family-relational-psychosexual intervention is feasible and acceptable for couples affected by prostate cancer in the context of one care-delivery setting. Subsidiary to this, the study aims to understand what processes of randomisation are plausible for a larger trial, determine a sample-size calculation for a definitive trial, and estimate the efficacy of the intervention to increase sexual and relationship functioning.
Design a family-relational-psychosexual treatment for delivering a couple-based intervention.
Determine the acceptability and feasibility of the intervention to patients, partners and healthcare professionals in the context of one care-delivery setting.
Determine sample size, recruitment and randomisation processes for a definitive trial.
Establish long-term cost implications to be addressed in a definitive trial.