Retesting the psychometric characteristics of the European cancer research and treatment organization’s quality of life questionnaire palliative care 15 Turkish version (EQRTC QLQ C15-PAL) and evaluating the influencing factors Tugba Yavuzsen a, * , Zeynep Sevgen Guc b , Ozlem Ugur c , Murat Bektas d , Ilhan Oztop a a Dokuz Eylul University, Institute of Oncology, Division of Medical Oncology, Izmir, Turkey b Dokuz Eylul University, Faculty of Medicine, Department of Internal Medicine, Division of Medical Oncology, Izmir, Turkey c Dokuz Eylul University, Department of Oncology Nursing, Faculty of Nursing, Izmir, Turkey d Dokuz Eylul University, Department of Pediatric Nursing, Faculty of Nursing, Izmir, Turkey article info Article history: Received 22 June 2017 Received in revised form 4 August 2017 Accepted 7 August 2017 Available online 12 January 2018 Keywords: Cancer Palliative care Quality of life abstract Purpose: The study aimed to retest the reliability and validity of the European Organization for Research and Treatment of Cancer-Core Quality of Life-15 Items Questionnaire for Palliative Care (EQRTC QLQ-C15- PAL) for the Turkish society and examine the influencing factors. Methods: The study was conducted in cancer patients who applied palliative treatment in the Dokuz Eylul University Oncology Institute Medical Oncology Division between May of 2014 and January of 2015. The demographic data collection form, performance status, and the EQRTC QLQ-C15-PAL scale were employed in order to gather data. Results: A total of 164 patients completed the study. The total Cronbach's alpha value for the scale was 0.794. The mean scores including the overall questionnaire, and subscales, which were calculated after two measurements conducted at an interval of three weeks, presented a statistically significant differ- ence (p < 0.01). Patients with higher and lower ECOG scores had significant differences in terms of total QLQ-C15-PAL questionnaire scores as well as its subscales of physical, emotional functioning (PF, EF), and fatigue (FA) (p < 0.05). The statistically significant differences between patients' ECOG scores and QLQ- C15-PAL total score, and PF, EF, FA, and pain (PA) scores were 0.375, 0.439, 0.245, and 0.221, respectively (p < 0.001). The QLQ-C15-PAL questionnaire is able to measure 94.0% of the factors measured by the QLQ- C30-PAL. The variables included in the model affected the patients' quality of life to the extent of 44.0%. Conclusion: It has been shown that the scale is a valid/reliable instrument to detect the quality of life of Turkish cancer patients. © 2018 Production and hosting by Elsevier B.V. on behalf of Turkish Society of Medical Oncology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/). 1. Introduction Scientific and medical advances over the last century have ensured a longer and more comfortable life and deferred death. 1,2 The World Health Organization defines palliative care as “an approach that improves the quality of life of patients and their families facing the problem associated with life-threatening illness, through the prevention and relief of suffering by means of early identification and impeccable assessment and treatment of pain and other problems, physical, psychosocial and spiritual,”. 3 Pallia- tive care was used in the early 1990s to provide patients dying of cancer with care in the United States and the majority of palliative care programs were launched for patients with cancer. 4 It is a family- and patient-centered approach that prioritizes patients' and their families' needs and seeks to improve the life quality of both patients and their families. 5 It is critical for patients with cancer to maintain their life quality as high as possible and continue their lives by assuming the responsibility of their own treatment and care. Therefore, it is important to evaluate the symptoms deteriorating the patients' quality of life and introduce them to the influential factors. 6 * Corresponding author. Dokuz Eylul University (DEU), Institute of Oncology, Division of Medical Oncology, Balcova, Izmir, Turkey. E-mail address: tugba.yavuzsen@deu.edu.tr (T. Yavuzsen). Peer review under responsibility of Turkish Society of Medical Oncology. Contents lists available at ScienceDirect Journal of Oncological Sciences journal homepage: https://www.elsevier.com/locate/jons https://doi.org/10.1016/j.jons.2017.08.002 2452-3364/© 2018 Production and hosting by Elsevier B.V. on behalf of Turkish Society of Medical Oncology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Journal of Oncological Sciences 4 (2018) 35e39