This review showed that adequate dyadic coping may improve relationship functioning, while dysfunctional dyadic coping may impede relationship functioning. In order to increase the comparability of the reported findings, a more uniformly conceptualized perspective on dyadic coping is needed. A better understanding of the dyadic challenges couples coping with cancer may face and more insight on how to expand the dyadic coping of these coupes might facilitate improvements in the quality of cancer care. Couple-based intervention studies may increase the couples' relationship functioning. However, future research is needed to examine more specifically which couples may benefit from such interventions. Statement of contribution What is already known on this subject? Dyadic coping may influence the distress experienced by both members of the couple and their relationship functioning. Several reviews already reported on the potential of couple-based interventions to improve the dyadic coping of couples coping with cancer and on the beneficial effects of this coping on the psychosocial adjustment and relationship functioning of patients and partners (e.g., Badr & Krebs, 2012; Martire, Shulz, Helgeson, Small, & Saghafi, 2010; Regan et al., 2012). However, even though we now know that couple-based intervention might be useful, no systematic review has been conducted that focuses specifically on the mechanisms of dyadic coping itself. What does this study add? This review showed the importance of stress communication, supportive behaviours, and positive dyadic coping for the maintenance or enhancement of relationship functioning in couples coping with cancer. In addition, the dyadic intervention studies send an important message that encourages to further examine the potential benefit of such interventions in future. However, more consensus in the conceptualization and assessment of the dyadic coping styles is needed in order to increase the comparability of the reported findings.

SF was deteriorated in both sexes after cancer, which affected women's SE negatively. Attention towards sexual (dys)function in colorectal cancer survivors is needed.

Sexuality should be investigated prospectively from a biopsychosocial model, hereby including the quality of sexual life.

Our findings illustrate the need for patient-tailored sexual health care and the complexity of providing/receiving this care. An adequate referral system and training are needed to help HCPs engage in providing satisfactory sexual health care.

Patients and partners reported lower sexual, mostly similar marital, and higher general life functioning compared with norm scores. Moderate to high within-dyad associations were found. The LDS-SEM model mostly showed actor effects. Yet the longitudinal change in the partners' sexual functioning was determined not only by their own preoperative sexual functioning but also by that of the patient. Preoperative sexual functioning did not spill over to the other two domains for patients and partners, whereas the patients' preoperative general life functioning influenced postoperative change in marital and sexual functioning. Health care professionals should examine potential sexual problems but have to be aware that these problems may not spill over to the marital and general life domains. In contrast, low functioning in the general life domain may spill over to the marital and sexual domains. The interdependence between patients and partners implies that a couple-based perspective (e.g., couple-based interventions/therapies) to coping with cancer is needed.