Caregivers' involvement in the patients' cancer care path and in the decision-making process has become more frequent in the last decades and has been recognized by a growing empirical literature, according to which most patients and caregivers preferred a collaborative or supportive caregivers' involvement (Laidsaar-Powell et al., 2017). Throughout the treatment process, from diagnostic assessment onwards, oncological patients commonly face the dramatic experience of cancer with at least one caregiver at their side, deal with visits and treatment appointments, therapies' side effects, change in daily life, experiencing significant distress (Laidsaar-Powell et al., 2017; Laryionava et al., 2018; Fatigante et al., 2021). Caregivers generally belong to the family system, often they are the spouse/partner or the adult child of the patients, in rare cases even friends can play this role (Laidsaar-Powell et al., 2017), They provide emotional, informational, and functional support as well as practical assistance, also mediating the interaction and communication with the oncologists when care options are discussed, or decisions are made (Hobbs et al., 2015; Litzelman, 2019; Schulman-Green et al., 2020; Fatigante et al., 2021).

Laidsaar-Powell et al. (2017) developed a conceptual framework (TRIO) according to which caregivers are involved in various ways in the decision-making process, concerning primarily the daily management of cancer treatments' effect. Patients almost always involve caregivers in the decision-making process, transforming the classic patient-physician interaction into a triadic relationship (patient, caregiver, and physician) (Mitnick et al., 2010; Renzi et al., 2016; LeBlanc et al., 2018). Nevertheless, patients and caregivers may have different perspectives regarding treatment decisions, experiencing episodes of conflicts or tensions between them, especially in the advanced cancer and the end-of-life context (Levine and Zuckerman, 1999, 2000; Vivian, 2006; Kramer et al., 2010; Hauke et al., 2011; Boelk and Kramer, 2012; Shin et al., 2016; Longacre et al., 2018; Benson et al., 2019; Hansen and Tjørnhøj-Thomsen, 2020). Such disagreements may have a negative impact on the patient, affecting the understanding of medical information, compliance with therapies and, consequently, the patient's quality of life, including the relationship with the caregiver (Shin et al., 2016). Poor disease-related communication between cancer patients and caregivers could increase the levels of psychological distress for both parties, making the course of treatment more complex (Speice et al., 2000). Instead, when patients and their caregivers are in line with the decisions to be made and their preferences are met, the process of care is enhanced for all the parties involved (Speice et al., 2000; Joosten et al., 2008). Moreover, caregivers' involvement in the oncological examinations was associated with both increased patients' satisfaction with respect to the care process and improved understanding of cancer-related information (Joosten et al., 2008; DuBenske et al., 2010a,b). More broadly, Krieger (2014) suggests the importance of an alignment among patient-caregiver preferences for the extent of caregiver involvement in the decision-making process.

The issue of caregivers' involvement in the therapeutic path has been also conceptualized within the ethical and bioethical literature. Within this literature, caregivers' involvement has been discussed in relation to the concept of autonomy. While some authors promoted an interpretation of autonomy as self-determination (Beauchamp and Childress, 2019), thus suggesting that the caregivers have only a supportive role (Mitnick et al., 2010), the vast majority of contemporary contributions on the topic tend nowadays to endorse the concept of “relational autonomy” (Gómez-Vírseda et al., 2020). According to the latter, people are not solipsistic agents but are defined by their relationships and depend on “significant others” to make decisions. This way, caregivers might often influence a patient's decision-making process regarding medical treatments, bringing with them a range of emotional reactions, interpersonal dynamics, and expectations (Hobbs et al., 2015; Laidsaar-Powell et al., 2016; Shin et al., 2016; Longacre et al., 2018).

Regardless the evidence about the effects that patient-caregiver interaction may have at both a psychological and decision-making levels, few studies assessed the effectiveness of psychosocial interventions, aimed at helping caregivers to be more involved in the treatment decision-making (TDM) process (Garvelink et al., 2016). Other studies focused on the effectiveness of dyadic psychological intervention on distress management (e.g., anxiety, depression, hopelessness, etc.) and patients' Quality of Life improvement (Regan et al., 2012; Griffin et al., 2014; Hu et al., 2019). The contents of psychological intervention protocols were psychoeducational, skills training or therapeutic counseling (e.g., anxiety, depression, hopelessness, etc.). These interventions could be either couple-based interventions involving both the patient and the caregiver in the same session, or interventions offered to the caregiver only, or to the caregiver and the patient independently in separate sessions (Hu et al., 2019).

Drawing upon this background, this study protocol aims to firstly evaluate the efficacy of a dyadic psychological support consultation for newly diagnosed breast and prostate cancer patients-caregivers on their level of agreement related to TDM, through a randomized research design. We also want to estimate related improvement in patient' compliance/adherence to treatments, together with the satisfaction with the (shared) medical decisions, and their psychological distress. We focus on breast and prostate cancer patients not only for a pragmatic reason, being the two most common disease in women and men, respectively, but even because they can have an early detection, so that we can explore caregivers' involvement from the diagnosis onward (Northouse et al., 2007; Dorros et al., 2010; Segrin and Badger, 2010; Oliveri et al., 2020b). Moreover, breast and prostate cancers belong to those types of cancers where caregivers' involvement can be necessary, since some decisions for therapies also involve the sphere of intimacy and fertility (Northouse et al., 2007; Dorros et al., 2010). In these cases, partners ideally play a fundamental role in making decisions, insofar as the decision has an impact on them as well (Segrin and Badger, 2010; Muzzatti et al., 2020; Cincidda et al., 2022). For this reason, the promotion of specific interventions to support dyads facing the diagnosis of breast or prostate cancer becomes even more crucial.

Accordingly, this study presents the following interrelated hypotheses:

People who take an active role in their health have a greater feeling of control and are more likely to adopt positive health behaviors (Arnaboldi et al., 2017; Oliveri et al., 2020a, 2022; Ongaro et al., 2022). For this reason, patient empowerment is more important than ever to manage a serious condition like cancer: patients are often called to make decisions together with their oncologists about the treatment to undergo, favoring the shared decision making (Howell et al., 2021). However, patients are often accompanied by at least one caregiver, who play a fundamental role in the shared decision-making process.

The role of caregiver in the shared decision making is not yet clear: sometimes he/she can be a facilitator, other times he/she can be a barrier to shared decision making. For that reason, the present research intends to verify whether a psychological support intervention can improve the triadic communication between patient, caregiver, and physician, and consequently the patient's adherence to treatments and the satisfaction with medical decisions.

We expect a positive impact of such intervention on patient's anxiety, depression and distress, and improvement in the perceived social support. Furthermore, this study would like to evaluate whether the patient's preferences on the involvement of the caregiver during the oncological care path depend on relational dynamics and/or on individual psychological variables.

Moreover, through this study we would explore if the presence of disagreements between patient and caregiver can affect the patient's cancer care pathway, both in terms of both in terms of processing the information received from the doctors and the adherence to therapies. Finally, the present study aims to investigate the ethical consequences that might emerge from the involvement of the caregiver. For these purposes, a concurrent longitudinal investigation will be performed.

Data gathered from this study may inform health care providers, policy makers, and public health managers about the caregiver's involvement and how to regulate it.

The potential impact of this project is also to start developing a specific intervention protocol to promote a functional caregivers' involvement in cancer care pathway, improve patient's wellbeing, the interaction with physicians and the patient's compliance with the cancer treatment.

Notwithstanding, it is necessary to mention some of the limitations that can be linked to this study. First, the inclusion of caregivers with different relationships with patients (all possible dyads are included) can create non-homogeneity in the sample composition, as there may be specific relationship factors that influence the results. In addition, there may be a large loss of participants in the control group, that might not see any direct advantage in participating, so it may be strategic to remind them that they may require hospital-provided psychological support at the end of the study (albeit for a fee).

Despite these limitations, the results that are expected to be obtained after conducting this trial may be useful in helping patients-caregivers' dyads during the cancer care path to reduce possible disagreement within the dyads and enhance patients' adherence to cure and the satisfaction with the decision made and more in general to better their daily life.

The present study is compliant with the recommendations set forth in the Helsinki Declaration (World Medical Association, 2013) and the CIOMS Guidelines (Bandewar, 2017), as well as with the principles of biomedical ethics reported in the Belmont Report (Department of Health, Education, and Welfare and National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research, 2014). This study presents a fair balance between risks and benefits, both for study participants and for future patients affected by the same condition of enrolled patients. Since the study is not a clinical trial, no physical risks directly related to the participation in the research are expected. Although psychological risks are not expected too, in case these raised from participation, psychologists responsible for the study will promptly intervene and take care of the patient. In particular, the reference psychologist can take charge of the patient or caregiver by proposing a psychological support intervention or send them to colleagues of the division for a psychotherapy intervention or otherwise send them to colleagues in the patient's or caregiver's territory of origin. Regarding the benefits, this study can improve patients and caregiver's awareness of their own decisional and psychological state. The dyads enrolled in the experimental group will benefit from psychological support that may hopefully improve the relational synergy, the communication processes and, more generally, the relationship between the two. Psychological support will also help the dyad to get to know each other better both in aspects related to the decision-making process of care and to the needs of both. Finally, the study will enable the development of a personalized psychological decision support system that will hopefully help both enrolled and future patients to better cope with the disagreement that arises within the dyads and have a more shared decision-making process. All this will make it possible to leverage the increasing need for a multidisciplinary team for patients entering the hospital. The principle of self-determination is also respected. A devoted informed consent form will be signed by participants before participation. Sign on the informed consent form will be proceeded by a dialogic consent process necessary to ensure informed voluntary and aware participation in research. Regarding respect for privacy, the study will be carried out according to the General Data Protection Regulation, Regulation (EU) 2016/679 (Holmes-Rovner et al., 1996). All data will be collected in a pseudo-anonymized form. As to the main study, data will be analyzed in an anonymous manner, whereas as to the empirical bioethics study these will be analyzed in pseudo-anonymized form. Data will be treated confidentially and used only by the collaborators in the present study for scientific purposes related to what stated in the research protocol. Ethical approval has been obtained for this study from the Local Research Ethics Committee of the IEO (Approval Number: R1598/21-IEO 1702).

CC conceptualized the ideas, made up the entire protocol and wrote the first draft in collaboration with VS and SO. CC, SO, and VS wrote, reviewed, and edited the manuscript. GP contributed with important intellectual content and supervised the whole process. All authors contributed to the article and approved the submitted version.

The present work was partially supported by the Italian Ministry of Health with Ricerca Corrente and 5 × 1000 funds for IEO European Institute of Oncology IRCCS.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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