Metastatic breast cancer (mBC), also termed advanced or secondary breast cancer, occurs when the primary lesion spreads to other sites of the body, most commonly the bones, lungs, brain, or liver. In recent years, new targeted systemic therapies have improved the median overall survival of many patients with mBC, and some patients may be cured by combination therapy or have long-term responses. However, resistance to treatment remains a significant challenge, so most patients will eventually progress and die from their disease [1].

Prognostic disclosure—communicating the likelihood that a certain clinical state or outcome will occur within a certain period—is now a routine part of cancer care in many countries [2]. Grounded in the ethical principles of autonomy and self-determination [3], prognostic disclosure enables shared decision-making by keeping patients informed about their health and involved in treatment-related choices, especially in situations of uncertainty. Patients who understand their prognosis tend to have more realistic expectations about treatment [4]; they are also better able to prepare for the future, have higher quality end-of-life (EoL) care and have better chances of dying in their preferred place [5]. Conversely, concealing a poor prognosis interferes with patients’ autonomy and ability to make treatment-related decisions that are aligned with their values, preferences, and goals, often resulting in the pursuit of futile therapies and poor symptom management [3,6].

To promote the value of prognostic disclosure and help clinicians become more familiar with it, consensus guidelines specifically addressing patient-clinician communication have been developed [7]. Yet, many oncologists continue to feel uncomfortable communicating prognostic estimates to their patients, often due to concerns about causing psychological harm and diminishing hope [8-10].

Research on prognostic awareness and its association with anxiety, depression, and quality of life (QoL) among patients with metastatic cancer supports these concerns to some extent, as the evidence is not uniform. Some studies report that prognostic awareness is associated with low anxiety, low depression, and high QoL [11], while others report a varied range of outcomes, including negative psychological impacts [12]. This may reflect the fact that prognostic disclosure that successfully balances hope and realism requires skillful, empathic communication [12-14].

Apart from these possible harms, other barriers to prognostic disclosure have been identified. Prognostication is inherently uncertain, owing to the randomness of future outcomes and the lack of evidence on the probability of outcomes. This lack of evidence is increasingly prominent in oncology because of the rapid pace of advancements in personalized medicine and novel therapies and techniques [15]. In mBC, reducing prognostic uncertainty is especially complex, as the clinical behavior of mBC varies greatly, and the disease trajectory is difficult to predict [16-18]. In addition, studies have found that timely discussions about EoL care, documentation of patient preferences in health records, and quality of care at EoL are particularly lacking for patients with mBC [19]. Thus, it is perhaps not surprising that this patient population has been found to be at increased risk of being overtreated at EoL [20,21], with insufficient access to hospice services and often dying in acute care environments [19].

Despite this landscape, the increasing incidence of mBC, and the large number of patients living with the disease, a preliminary literature search has shown that, to date, knowledge about prognostic disclosure in mBC has not been systematically mapped.

The overall aim of the proposed scoping review is to identify, summarize, and synthesize knowledge about prognostic disclosure in mBC. We expect that the results of this work will facilitate further research aimed at gathering evidence and gaining insights on the process and outcomes of prognostic disclosure in mBC to help guide medical professionals in challenging yet crucial conversations with patients.

This scoping review will be conducted following the widely known 5-stage framework by Arksey and O’Malley [22] and subsequent recommendations [23,24]. The results will be reported in accordance with the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines.

A scoping review is a rigorous, transparent tool that can be used to map or synthesize a range of evidence in order to convey the size and scope of a research field [24]. According to Arksey and O’Malley [22], by conducting a scoping study researchers can survey the extent, range, and nature of research activity in a given field, establish whether a full systematic review is warranted, summarize and disseminate research evidence, or identify gaps in the existing literature.

Compared to systematic reviews, which aim to summarize the best available research related to a given research question, scoping studies generally do not critically evaluate the quality of the studies they cover [25,26]. Compared to narrative or literature reviews, scoping reviews require analytical reinterpretation of the literature. Scoping reviews are helpful when evidence on a topic is emerging or the relevant literature is complex or heterogeneous. In addition, they can cover findings from a range of different study designs and methods [24]. Thus, they are well-suited to synthesizing the literature on a topic that has yet to be comprehensively mapped, such as the one we will endeavor to review.

The research questions of this scoping review are the following: What has been reported about prognostic disclosure in mBC? What are the knowledge gaps regarding prognostic disclosure in mBC?

An exploratory search in PROSPERO—the International Prospective Register of Systematic Reviews of the National Institute for Health Research—and the Cochrane Library revealed no comprehensive systematic reviews addressing similar questions. The research team will revise the protocol as appropriate during the review process.

Results retrieved from all databases will be imported into a reference management software, and duplicate references will be removed. At the first screening stage, 2 researchers will independently review the title and abstract of all references and assess them for eligibility. Disagreements will be discussed until consensus is reached, and if necessary, by consulting a third independent researcher. Articles not related to the topic, theses, articles from the popular press, reports, nonreviewed books and book chapters, presentations, and opinion pieces will be excluded. The 2 researchers will then independently conduct the second eligibility screening, evaluating full-text articles against the inclusion and exclusion criteria. Results will be compared, and any disagreements will again be discussed to reach a consensus on final inclusion, involving the third researcher if needed. A PRISMA-ScR flowchart will be developed to report the process.

Based on the recommendations by Levac et al [24], we will perform a descriptive quantitative synthesis and a thematic analysis. In line with Arksey and O’Malley [22], our descriptive quantitative summary will begin with the final number of articles included in the scoping review and the essential characteristics of the articles identified, such as first author, year of publication, country, discipline/field of inquiry, study design (ie, qualitative, quantitative, mixed methods, retrospective, prospective, longitudinal, and cohort study), research methods, type of health professional and/or patient involved, number of participants, etc. This information will be presented in the scoping review report to provide an overview of the included literature.

For qualitative data, content analysis will describe the data extracted, highlighting consistencies and differences [29]. The articles will be coded following a multistep process, including open coding, axial coding, and selective coding, using the Dedoose web-based application [30]. In the first phase, units of meaning will be identified and labeled to allow categories to emerge from the data (open coding). Open codes will be categorized, with similar codes grouped, refined, and combined into larger themes (axial coding). The conceptually stable thematic patterns that emerge will then be organized and grouped into higher-order conceptual themes. Selective coding will involve integrating and refining of these concepts [29]. Finally, findings will be integrated and validated through discussion among all members of the research team.

The essential characteristics of the studies will be tabulated, providing an overall summary of the articles selected. Other results will be presented in diagrams and descriptive summaries, as most appropriate to display and convey the extracted information.

The scoping review methodology consists of reviewing material that is publicly available and does not involve any patient-related data, so this study is not subject to ethical approval.