Research priorities on post‐traumatic growth: Where next for the benefit of cancer survivors?

The old adage, “What doesn't kill you makes you stronger” may at times be offered as a platitude to those going through diagnosis and treatment for cancer. The idea that traumatic or highly challenging life experiences and the struggles that accompany them may eventually lead someone towards positive changes in behaviour or life outlook has been much explored in cancer survivorship studies, most commonly using the term “posttraumatic growth” (PTG). We propose that there is a need for a focused future research agenda so that the study of PTG translates into benefits for cancer survivors. As a first step in forming that agenda, and to stimulate debate and further enquiry, we suggest five key areas to be addressed.


| BACKGROUND
The old adage, "What doesn't kill you makes you stronger" may at times be offered as a platitude to those going through diagnosis and treatment for cancer. The idea that traumatic or highly challenging life experiences and the struggles that accompany them may eventually lead someone towards positive changes in behaviour or life outlook has been much explored in cancer survivorship studies, most commonly using the term "posttraumatic growth" (PTG). 1 We propose that there is a need for a focused future research agenda so that the study of PTG translates into benefits for cancer survivors. As a first step in forming that agenda, and to stimulate debate and further enquiry, we suggest five key areas to be addressed.

| Terminology and definitions
PTG has been defined as an unplanned and unexpected emotional, behavioural, or cognitive change which occurs after a life crisis and struggle and following a period of reflection and rumination; it is both a process and an outcome following trauma. 1 The cancer experience differs from an acute event such as an accident or natural disaster; it is focused on the body and highly medicalised. Initial concerns may be around diagnosis and prognosis, but later may (also) relate to treatment experiences or ongoing sequelae. It is, therefore, difficult to define both the nature of any cancer-related trauma and its aftermath.
This makes systematic identification and synthesis of the literature on PTG extremely challenging. Moreover, it is unclear whether these terms refer to the same construct(s). Where appropriate, researchers should clearly reference the construct(s) being examined in their work and how this/they is/are defined and interpreted. In addition, rigorous scoping work would identify the range of terms used in cancer survivorship research and where there may be inconsistencies.

| Measurement and determinants
Several scales have been used to measure PTG. Whether these are multi-dimensional or (all) measure the same (single) overarching construct of positive change remains unclear. 2

| Understanding pathways to growth
The route towards PTG for cancer survivors may be highly complex.
Several have questioned what might represent "genuine" PTG. focus is now needed on process(es) rather than outcome.

| Understanding potential corollaries of PTG
It is important to determine whether cancer survivors who report PTG experience additional psychosocial (or other) benefits than those who do not. Studies have tentatively suggested positive associations between moderate-to-high PTG and health-related quality-of-life (HRQoL) 6 and PTG and psychological wellbeing. 7 Better understanding of these associations is of considerable importance, especially as HRQoL is gaining recognition as an independent prognostic factor in cancer. 8

| Informing intervention development
If PTG does hold additional benefits for cancer survivors, the next natural step should be to determine whether it can be facilitated and enabled. Guidance on intervention development points to a need to review published evidence, draw on existing theories, understand the context in which the intervention will be implemented, and involve key stakeholders who may benefit. 9 The formative evidence on PTG determinants and pathways is currently insufficient to form a basis for intervention planning. Filling the gaps is an essential precursor to intervention design work, which should involve patients, carers and Key Points potential service providers. Iterative refinement and optimisation involving users will result in interventions ready to be tested in the "real world", initially in terms of acceptability and feasibility and subsequently in terms of efficacy.
Importantly, any focus on PTG within interventions to support cancer survivors does not mean that the negative consequences of cancer should be disregarded or downplayed. PTG and associated terminology should not be presented as an expected outcome following cancer as this may lead to feelings of negativity or pressure 10 ; the focus should be on aspiration rather than expectation.

| CONCLUSIONS
Post-traumatic growth is a complex phenomenon. Better understanding of how and when it is experienced, how to measure it, what influences its development and how any benefits might be enabled would make a hugely valuable contribution to cancer research. A focus on these key areas can lead towards more evidence-based long-term support for survivors-working towards the goal that lives following cancer are lives lived well.