BackgroundInformation and discussion of sexual changes with a health professional is a high priority for many cancer patients in order to assist with sexual changes and ensure that sexual intimacy does not cease post-cancer. The PLISSIT model is widely recommended as a framework for providing sexual information and support, allowing for the discussion of sexual changes at various levels of increasing intensity. The aim of the present study is to evaluate the early stages of the PLISSIT model by examining the relative efficacy of written information provision about cancer related sexual changes, and information provision accompanied by a single session of counselling, for people with cancer and their partners, across a range of cancer types.MethodEighty-eight people with cancer and 53 partners across a range of sexual and non-sexual cancers, took part in a randomised trial which adopted mixed method analysis to examine changes in psychological wellbeing, quality of life, relationship satisfaction and communication, and sexual functioning, following written information provision about cancer related sexual changes (self-help condition; SH), or written information accompanied by a single session of counselling (health professional condition; HP).ResultsRatings of the usefulness and efficacy of the SH and HP interventions, collected through analysis of Likert scales, open ended survey items and interviews, indicated that both conditions were found to be useful and efficacious by the majority of participants, serving to increase awareness of sexuality, improve couple communication about sex, and help in the management of sexual changes, through the exploration of non-coital sexual practices. In contrast, the quantitative analysis of standardized instruments found no significant improvements in psychological wellbeing, quality of life, relationship satisfaction and communication, or sexual functioning. There were significant reductions in self-silencing in the HP condition, and a trend towards increases in sexual satisfaction across both conditions.ConclusionThese results offer support for the early stages of the PLISSIT model, in terms of normalization and increased awareness of sexual changes after cancer, increased couple communication about sexual changes, and legitimation of exploration of a range of non-coital sexual practices and intimacy. However, more complex and intensive interventions are needed to address sexual functioning and psychological wellbeing. The findings provide support for the proposition that providing permission to discuss sexuality should be the core feature underpinning all stages of interventions designed to provide sexuality information and support for people with cancer and their partners, and also demonstrate the potential importance of limited information and specific suggestions.Trial registrationThis study was registered in the Australian New Zealand Clinical Trials Registry.(ACTRN12615000399594) on 29 April 2015.