The study identified 17 subthemes grouped into five major themes. The most striking finding was that many of our informants described the decision to participate as instant, taken even before they had been given full information about the clinical trial in question. The decision was guided more by emotion than conscious deliberation. The patients stated that the decision to participate was obvious, immediate and easy. It was not guided by the written or oral information on the trial, which they only skimmed through or registered fragments of, but rather based on a positive gut feeling.
This immediateness of patients’ decision-making process has, to our knowledge, rarely been described before  and it can be understood through theories in cognitive psychology. Extensive work has been done regarding theories of dual processing in decision-making, where fast intuitive and emotion-driven System 1 processes are contrasted with the slow analytic procedures of System 2 [21, 22]. It is assumed that the fast System 1 processes cue default intuitive judgements, that in some cases are later endorsed by the analytic System 2. This is in accordance with our findings, where the patients described an immediate decision to participate, based on hopeful and positive feelings towards the physician and research in general. This fast, emotional process was sometimes followed by a slower cognitive process. Here, they examined the oral and written clinical trial information more closely and discussed their decision with others to confirm it. However, some did not find this slower process necessary but were satisfied with their immediate decision. This fact points to the importance of not regarding the decision-making process as solely, or even primarily, a cognitive process. A study by Yang et al. confirms the importance of emotions in cancer patients’ decision-making, presenting data that emotions play a significantly greater role for them compared to a representative national sample . Taken together, this suggests that written information may be less important for the decision process than is generally assumed.
In some cases, the referring physician had taken up the issue of clinical trials before the patient arrived at the oncology department; this may have contributed to a faster decision-making process there, as the patient had time to consider the question beforehand. Furthermore, epidemiological studies have shown that pre-notification significantly increased participation in clinical trials . This is in line with other research  and points to the importance of regarding informed consent not as a single event but rather as a multistage process.
Another interesting finding is that the patients attached great importance to the relational aspects of the decision-making process, referring to the fact that they trusted the physicians, the research nurses and researchers. This trust made them feel safe and secure with their decision to participate in the clinical trial, which is in line with previous studies [26, 27]. Another important aspect was that trial participation would result in closer follow-up and more direct access to care, through the research nurse in particular. Many of our patients were also convinced that the clinical trials were based on certain assumptions about the positive effects of the drugs being tested and, despite information about the risk of side effects, patients valued the chance of receiving effective treatment for their cancer so highly that they accepted the risk of side effects. This finding is in accordance with Madsen et al.  who found that trial participants tended to concentrate on possible differences in treatment effects and often considered the experimental treatment option to be superior. This misconception is an important issue to address in order to achieve informed consent based on a correct understanding of the trial design.
Some patients described not actually having the choice to decline, either because they felt they had to rely on the physician’s knowledge, which they considered more expert than their own, or due to the fact that participating in the trial was the only possibility to access further treatment for their form of cancer. These patients were often in a palliative situation. Under a serious life threat, there may be even more difficulties in cognitively processing information about a clinical trial. Furthermore, some patients had an unrealistic belief that the treatment was curative due to not understanding that the cancer situation was palliative. Again, this raises the question as to whether truly informed consent actually exists under these circumstances . Moreover, many physicians find it difficult to bring up the issue of palliative care as a treatment option, due to fear of taking away the patient’s hope, thus tending to avoid the subject altogether . It is therefore vital that the decision to participate in a clinical trial is preceded by an honest discussion about the possible positive and negative effects, including other existing treatment options where one of the options described should be palliative or best supportive care. This approach is also suggested by Godskesen  and is of great importance since supportive care may actually lead to increased life expectancy with better symptom control than a continued tumour-directed treatment, as shown in a lung cancer study by Temel et al. .
Our most expected finding was the theme ‘Hoping for help while helping others’, which is in accordance with other studies, where these aspects were the main reasons for cancer patients to participate in a clinical trial [10, 33,34,35]. The patients were grateful to previous patients who had contributed to the current treatments and wanted to make the same effort for future patients. They considered themselves part of a context in which different contributors cooperate for the common good. This reasoning can be considered a kind of coping strategy aimed at making a difficult situation more meaningful, as described earlier by Godskesen et al. .
The trustworthiness of the study results can be discussed in relation to credibility, confirmability, dependability and transferability [18, 37,38,39]. The credibility of the study was strengthened by the use of open-ended interview questions, which made it possible for the patients to speak freely about their reasoning regarding participation in a clinical cancer trial. An interview guide was used to ensure that each interview covered topics that were considered central. The sample size of 27 patients was deemed sufficient to reach understanding of the phenomenon in question.
The three authors performing the analysis have different backgrounds and experiences. The first author is a consultant physician in oncology and psychiatry. The second is a specialist nurse with a PhD in the field of patient perspective and involvement and the third is a registered nurse and professor in healthcare pedagogics. These differences have been valuable during the process of analysis to reinforce confirmability, as they have facilitated the reflexivity of the analysers concerning preconceptions and interpretations during the analytic process. The analysers’ different professional backgrounds, knowledge and experience of meeting patients in clinical settings have contributed to a richer and more developed understanding and interpretation of the patients’ reasoning.
The dependability of the study has been supported by the accurate and detailed description of the data collection and analysis. The open-ended interviews have contributed to obtaining varied and rich descriptions of the patients’ reasoning. The patients’ quotes illustrating the themes and subthemes strengthen the consistency of the results.
Limitations and strengths
The most important limitation is that we only included patients who had agreed to participate in a clinical trial, not those who had declined participation. Such selection of informants may only cover certain aspects of the decision process and hence give an incomplete picture. For example, our finding that few of the patients were concerned about the side effects of the trial treatments may in part be explained by the fact that this is a main reason for patients to decline participation . Consequently, our study sample would rarely include patients with these opinions. Furthermore, the concept of clinical equipoise was referred to in accepting terms, as helping out by being ‘a bit of a guinea pig’ when the experts do not know which treatment is best. This is in accordance with Mills et al., who found that patients accepting the idea of clinical equipoise tend to consent to randomised trials . However, the immediate decision process described by our patients may also be present in patients declining to participate and would be interesting to address in another study.
Our reason not to include any declining patients was based on an ethical consideration of not wanting seemingly to call their decision into question through our examination of the decision process. This may have been too cautious, and the disadvantage of not including the decliners is that they may have provided valuable insights into the obstacles to participation in clinical trials that patients experience, which in turn may have contributed to the improvement of inclusion procedures in the future. According to these findings, it is very important to carry out a further study on the reasoning of patients who declined participation.
The study has several strengths. The patients were interviewed soon after their decision to participate, which decreased the risk of memory errors. Moreover, this proximity in time ensured that the views of patients in a late palliative stage were also captured. The patients included represented many different aspects of cancer patients and trials. The patients were men and women of different ages. They had different cancer diagnoses at different stages, both curative and palliative, and participated in many different clinical trials ranging from phase I to III, testing a range of different treatment modalities. This diversity is an important aspect of qualitative studies with an explorative intent.
The findings in this study, as in other qualitative studies, do not claim to be generalizable. However, given the above, the results of this study should be transferable to similar contexts in other western countries.