1. Introduction

In women, breast cancer is the most common disease in incidence (2.1 million new cases in 2018) and mortality (627,000 deaths in 2018) when compared to all cancers [1,2].

In the past century, most women did not survive breast cancer [3], but, more recently, earlier diagnosis, effective screening programs and advanced medical treatments have been increasing the number of survivals in a 5-year rate [4].

Traditionally, in the oncology literature, greater attention has been paid to the psychiatric, psychological and psychosocial impact of the pathology. Several studies analyzed the adaptive reaction strategies of patients at the medically defined points such as diagnosis disclosure, treatment consents, disease recurrence and palliative cares initiation [5,6,7].

According to existing literature, the issue of breast cancer survivorship brings attention to the end of treatment perspective [8,9,10]. In this regard, Carter [11] analyzed longitudinally the daily lives experience of 25 women aged from 40 to 78 years who had survived breast cancer. Participants highlighted how the end of the treatment represents a crucial moment during which they can retrace the cancer pathway: interpreting and understanding the diagnosis, confronting the idea of mortality, rearranging their life priorities, coming to terms with the diagnosis, being able to move on and flashing back to the experience. Thus, according to Carter, ‘going through’ this pathway suggests a past, present, and future life after the diagnosis for those affected.

From the early nineties, the awareness about the involvement of patients’ partners in the experience of cancer has become more evident [12,13]. Hence, a considerable body of studies has focused on the breast cancer psychological consequences for partners and other family members [14,15,16].

This has gradually led to consider breast cancer as a ‘we-disease’ [14], which takes shape in the context of the relationship [17]. In short, literature reviews and meta-analysis support the idea that dyads may react as a unit rather than as individuals when coping with cancer, which influences the distress experienced by both partners [18,19] and might impact their relationship functioning.

In this context, the dyadic approach has progressively entered the research studies’ design [20], and several studies in the breast cancer literature have investigated the correlations between a specific couple dimension and psychological adjustment [21,22,23].

In this context, just a few reviews have focused on the impact of breast cancer on the couple’s relationship [15,18,24,25]. They mainly reported the areas of interaction of breast cancer and the patient’s personal relationships: (1) general interactional themes of patients secondary to breast cancer (e.g., social isolation; victimization; uncertainty); (2) the impact of social support, including the support from partners on patients’ psychological adjustment; (3) the impact of the disease on the parent–child relationship. In addition, these reviews discussed the impact of breast cancer on marital level of satisfaction in terms of couples’ sexual relations and communication. Despite the emerging evidence on the impact of breast cancer on patients and partners, no systematic review has been conducted specifically on the relationship dynamics that can have a major impact on the psychological distress experienced by couples.

We used interdependence theory [26] and the investment model of commitment [27] to guide the development of the current study. Developed to clarify behaviors in dyadic relationships, the interdependence theory assumes that partners become interdependent over time through their interactions. The investment model implies that interdependence will be perceived as commitment, defined by partners’ desire to maintain the relationship through good and bad times [27].

2. Discussion

According to the breast cancer literature [48,49], diagnosis disclosure is experienced as a shock by couples mostly because of its terminal nature [35,43]. directly influence sexual functions and hormone levels [50]. Often women with breast cancer need endocrine adjuvant treatment that involves insufficient lubrication, dyspareunia and sexual arousal [51]. Resilient intimacy, as a unique dyadic process, is now considered a predictive factor for a couple’s positive psychological adaptation to cancer and other health adversities [32,53].

Communication within the couple can undoubtedly impact how the dyad copes with treatments [54]. Furthermore, couples who can develop constructive mutual communication, explore potentially hurtful disclosures, respond to partners’ obstructive behaviors regarding cancer-related issues seem to have a more positive psychological adjustment to the breast cancer experience [32,40,42]. First, it is important to highlight that open and shared communication about potential fears, worries or needs allows couples to share the experience with higher levels of satisfaction [17] and more successful coping efforts [21]. Furthermore, with reference to the optimal matching model of social support, adopting a complementary communication consisting of a mutual sharing of the emotional aspects of the care pathway increase the possibility of better matching of needs and reciprocal support [55].

In the oncological literature, the dimension of dyadic coping is defined as “the interplay between the stress signals of one partner and the coping reactions of the other, a genuine act of shared coping” [56] is considered as highly relevant for relationship outcomes in couples dealing with cancer. Couples deal with many potentially stressful challenges, such as emotional concerns and existential issues, medical treatment and its side effects, transformed sexuality and changed social relationships and roles during and after treatment. Longitudinal studies have shown how dyadic coping is identified as a protective factor for the couple’s relationship [56] and a predictor of a more positive couple’s psychological adaptation by protecting the dyad’s quality of life [25]. This appears to be in line with the results of this review showing how the couple’s ability to merge forces plays an important role in the dyadic coping strategies [35].

As pointed out in several studies [49,57,58], psychosocial support plays a key role in the treatment pathway for breast cancer. Beyond a supporting couple relationship, at the emotional and instrumental levels, the informal network plays a crucial role as well. Receiving psychosocial support from social networks increases self-esteem, reduces the stress associated with the disease and improves adherence to medical treatments [57]. In particular, the increase in treatment adherence can be determined by improved cognitive functioning, a sense of self-efficacy, intrinsic motivation, personal control, reduced emotional conflicts, distress and depressed mood [60].

In addition to communication, coping strategies, intimacy and psychosocial support, religiosity has been identified as a relevant dimension in couples’ dealing with breast cancer. Evidence shows that religiosity can have a positive impact on patients’ lives consisting of a decrease in negative emotional states, levels of distress, mood symptoms and hopelessness and an improvement in well-being and illness adjustment by promoting reflection and reconceptualization of the situation [14,33,62]. Furthermore, in regards to the African American population, praying together and, more generally, taking care of their own spirituality seems to favor couples’ management of the stressful situation [63].

Personality traits can be considered additional factors implicated in the relational functioning of couples facing the treatment pathway for breast cancer. The National Comprehensive Cancer Network (NCCN) has identified distress as “a multifactorial unpleasant emotional experience of a psychological, cognitive, behavioral, emotional, social, and/or spiritual nature that may interfere with the ability to cope effectively with cancer, its physical symptoms, and its treatment” [64,65]. Results have shown that high levels of distress and impaired quality of life are negative prognostic factors on the couple’s ability to adapt. Literature in this field highlights how the use of coping strategies by the members of the couple, which are exclusively centered on the problem, seems to favor higher levels of well-being and better psychological adaptation [66,67].

3. Conclusions

According to existing literature, a high relationship functioning during or after cancer treatment may depend on how properly the dyad incorporates and psychologically elaborates cancer issues into their lives. This highlights the need to increase awareness and consider breast cancer as a dyadic affair with a significant impact on the relationship. Findings from this systematic review shed light on the significant impact of breast cancer on relational functioning, showing how breast cancer impacts relational dimensions and on the complex interplay between partners.

Moreover, facing cancer as a ‘we-disease’ may result in a strengthening of the couple’s relationship. Indeed, considering breast cancer as a relational disease can facilitate the implementation of successful dyadic interventions aimed to develop or consolidate the relationship functioning. The positive implications of such an approach may be different: a greater awareness about the impact of the disease, the maintenance of a positive relationship functioning, the improvement of the compliance with care pathways, higher quality of life and better coping strategies in facing with disease fostering the process of psychological adaptation.

To our knowledge, this is the first systematic review that brings together and analyzes almost 30 years of studies in this field, thus summarizing the relationship dynamics that characterize couples during the breast cancer pathway after the acute phase of treatments. Although the review was rigorous and wide-reaching, there were a few limitations. We only searched for publications mentioned in English in peer-reviewed journals, theses, dissertations, conference proceedings and trial registries were excluded. Moreover, the study samples were small and not always fully described, and most studies had a cross-sectional design.

In conclusion, breast cancer strongly impacts the entire dyadic system. Clinicians and other health professionals can play a vital role in helping the couple to adjust to the psychological and psychosocial effects of breast cancer by adopting a collaborative approach and including dyads in the clinical consultations. Further research in this area should encourage new theoretical frameworks for the development of specific couple interventions to promote a positive psychological adjustment to the disease and, consequentially, to maintain the health of these relationships.

This entry is adapted from the peer-reviewed paper 10.3390/ijerph18147288