Introduction Recently, a gradual increase in some chronic diseases has been observed in tandem with the aging of the population. Globally, there has been a significant increase in the importance of cancer, and according to a recent report from the International Agency for Research on Cancer, its overall impact has more than doubled in the past 30 years [1]. The burden of cancer will increase to 22 million new cases each year by 2030: an increase of 75% compared with 2008, 81% in low and middle Human Development Index (HDI) countries and 69% in high and very high HDI countries [2]. The epidemiological transition in Brazil is not occurring as in most industrialized countries, but malignant neoplasms are already the second leading cause of death in the Brazilian population. In 2010, cancer deaths represented almost 17% of the deaths from known causes: 92.587 in males and 79.457 in females [3]. According to the World Health Organization, in less developed countries, like Brazil, most individuals with cancer have advanced disease at the time of diagnosis; therefore, the proportion of patients who require palliative care is enormous [4]. Palliative care is an approach that improves the quality of life of patients and their families facing problems associated with life-threatening illness through the prevention and relief of suffering [5]. Quality of life (QOL) is a multi-dimensional concept, which involves various domains such as physical, functional independence, psychological, social, spiritual, and existential wellbeing [6]. As QOL is the main focus of palliative care, assessing QOL is of paramount importance for evaluating the care offered to patients [7]. An ideal assessment of QOL should be performed using validated patient-reported outcome instruments [8]. For any instrument to be used in another country, translation and cultural adaptation are necessary to ensure equivalence between the original and translated versions [9] Validation of an instrument is also necessary to verify the extent to which the instrument measures what it is proposed to measure [10,11]. In Brazil, there are few validated quality of life questionnaire. Only the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 15 PAL (EORTC QLQ-C15-PAL)and the Palliative Care Outcome Scale (POS)are specific to patients in palliative care [12]. The validation study of the POS Abstract Background: As quality of life (QOL) is the main focus of palliative care, evaluating QOL is a very important aspect of the care offered to patients.