Abstract
Objective This metaresearch of the clinicaltrials.gov database aims to evaluate how clinical research on palliative care is conducted within the setting of advanced cancer. Methods Clinicaltrials.gov was searched to identify registered studies recruiting patients with cancer, and investigating issues relevant to palliative care. The European Organisation for Research and Treatment of Cancer QLQ-C15-PAL (Quality of Life in palliative cancer care patients) questionnaire was taken into account to define the research domains of interest. Studies investigating cancer-directed therapy, management of cancer treatment-related adverse events and diagnostic tests were excluded. Publication status was crosschecked using PubMed. Results Of 3950 identified studies, 514 were included. The most frequent reason for exclusion was cancer-directed therapy (2491). In 2007–2012, 161 studies were registered versus 245 in 2013–2018. Included studies were interventional (84%) or observational (16%). Most studies were monocentric (60%), sponsored by academia (79%), and conducted in North America (57%) or Europe (25%). Seventy-nine per cent of studies evaluated a heterogeneous population (>1 tumour type). Interventional studies most frequently investigated systemic drugs (34%), behavioural interventions (29%) and procedures for pain (24%). Pain, quality of life and physical function were the most frequently studied research domains (188, 95 and 52 studies, respectively). The most applied primary outcome measures were efficacy/symptom control (61%), quality of life (14%) and feasibility (12%). Only 16% of the closed studies had published results in PubMed. Conclusions Our study describes the heterogeneous landscape of studies conducted to address the issues of patients with advanced cancer in palliative care. Albeit the observed increase in the number of studies over the last decade, the generalisation of the results brought by the existing trials is limited due to methodological issues and lack of reporting. A greater effort is needed to improve clinical research that supports evidence-based palliative cancer care.