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The study was approved by the Medical Ethics Committee of the VU University Medical Center, Amsterdam. Besides, the participating departments (Neurology and Medical Oncology) gave their approval for the research to be carried out. Written informed consent to participate in the study and publish the results was obtained of all respondents at each interview appointment.
We conducted a qualitative descriptive study [28] in which in-depth interviews with advanced cancer patients were performed.
Two patient populations facing palliative treatment decisions were included in this study. The first group consisted of patients diagnosed with glioblastoma (GBM), the most common and most malignant type of primary brain tumor in adults, that underwent postoperative combined chemo- and radiotherapy [29]. These patients have a poor prognosis and cannot be cured of their disease. The median survival for these patients is approximately 14 months after diagnosis with current standard care [30]. The second patient population included in the study was a group of patients with metastatic colorectal cancer. Patients were eligible if they were diagnosed with metastatic colorectal cancer (stage IV) and were not eligible for operation. The median survival for these patients is 24-28 months with current standard care [31], and fewer than 5–8% of these patients are alive at five years from diagnosis [31], [32].The aims of chemotherapy in both patient populations are to prolong survival, control symptoms, and maintain or improve quality of life (e.g. relief of pain caused by tumor growth) [33]. Chemotherapy can be effective in prolonging time to disease progression and survival but these benefits must be weighed against treatment toxicity and the effect on quality of life (e.g. nausea and fatigue) [33]. In both patient groups, when progression of the disease occurs, a decision is often required on whether or not to start a (second-line) treatment aimed at prolonging life, but with the disadvantage of burdensome side effects. Patients diagnosed with GBM were included at the beginning of their adjuvant temozolomide chemotherapy, soon after the end of the postoperative concomitant chemo-irradiation. Metastatic colorectal patients were included at the beginning of treatment with first-line palliative chemotherapy.
Patients were recruited in a large university hospital through consecutive sampling. The study with GBM patients started in May 2010 and patients were included till December 2012. Recruitment for colorectal cancer patients started in November 2011 and ended in February 2013. Patients were eligible if they were over the age of 18, spoke and understood Dutch, had been diagnosed with either GBM or metastatic colorectal cancer, and had started with first line treatment. We considered all patient at the two departments that started with first line therapy during the inclusion period for our study. To identify the GBM patients the researcher (LB) attended multidisciplinary team meetings and two times a week a briefing where physicians prepared their out-patient clinic visits and patients' status and treatment plans were discussed. To identify metastatic colorectal patient the researcher attended a weekly briefing where physicians discussed new patients and their treatment plans. She also stayed in regular contact with physicians and nurses of the participating departments to identify eligible patients. During the inclusion period we identified 47 patients with GBM and 11 patients with colorectal cancer possibly eligible for our study. Of these, 15 GBM patients were not eligible because they already had progression of the disease before the moment of inclusion. Furthermore, 2 GBM patients were not approached, because the physician thought the study would be too burdensome for them. This led to 30 GBM patient and 11 metastatic colorectal patients that were eligible and were approached for our study. They were handed an information letter by their physician during their visit on the outpatient clinic and after one week, the researcher (LB) phoned the patients and explained the study aims and methods to them. Of these patients 12 GBM patients and 1 metastatic colorectal patient declined to participate in the study of whom 5 patients were not interested in the study, 5 patients felt they were too ill to participate, 1 patient said it was too emotionally demanding because she had problems with her speech, 1 patient was too stressed about how the disease would develop in the future, and 1 patient did not want the researcher to attend patient-physician conversations. This resulted in 28 participating patients (their characteristics are shown in Table 1), of whom 18 were diagnosed with GBM and 10 with metastatic colorectal cancer. The patients ranged in age from 27 to 82.
Table data removed from full text. Table identifier and caption: 10.1371/journal.pone.0100435.t001 Characteristics of participants *1 patient was not able to pick a card The in depth interviews lasted approximately 45–60 minutes and were held at the patients' homes. We used an interview topic list based on the objectives of the study. The list contained general questions about the patients' treatments so far; open-ended questions about their preferences for participation in future treatment decisions; communication with their treating physician and if they could imagine situation in which they would no longer want to receive treatment. The Control of Preferences Scale (CPS), developed by Degner [34], was used to start discussing the extent and type of influence patients wanted to have concerning treatment decision-making in the future. The CPS is a widely used tool to measure patient preferences for participation. The CPS is clinically relevant, easy to administer and valid in health care decision-making [34]. The CPS allowed the patient to choose one of five levels of involvement in decision-making, ranging from active to passive (Table 2). Further questions followed up on answers respondents provided and aimed to clarify why they had chosen a certain level of involvement. At the end of the interview the researcher checked whether all topics had been covered [35]. All interviews were performed by the first author (LB) and were recorded and transcribed verbatim. The interviewer kept field notes, describing her reflections on the interviews and the study.
Table data removed from full text. Table identifier and caption: 10.1371/journal.pone.0100435.t002 Control Preference Scale During the interview all patients said that they understood the severity of their disease and were aware of the fact that at some point in the disease trajectory the disease would progress and new treatment decisions must be made. They also knew that they would eventually die from the disease. They told that their treating physician informed them on their diagnosis after their surgery (GBM patients) or after CT scans were made (metastatic colorectal patients).
As our study was explorative, we used open coding as described by Strauss and Corbin [36]. Data analysis started during data collection and was an ongoing process. The constant comparative method was used to compare codes within and between interviews and to identify the main themes [37]. To ensure the reliability of the coding procedure, two researchers (LB and HRWP) independently read through the interviews to generate a list of codes (e.g. keeping control over own life, reaching consensus, shared responsibility, lack of knowledge, expertise physician and phase of illness), and compared their results. This revealed high agreement between the coders, and any disagreements were solved by discussion. The codes were discussed with two other researchers (with BDP and GAMW), and the group worked towards consensus about the interpretation of key themes. The main themes were identified and relevant quotes were chosen to illustrate these themes. The enrolment of participants was stopped once the analysis of the latest interviews did not generate new codes or enriching existing themes (theoretical saturation). A professional translator translated the quotes that we eventually chose to illustrate our results.
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