This study aims to synthesize the barriers and facilitators of oral nutritional supplement adherence in people with cancer and assess levels of adherence. Databases including Embase, PubMed, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang Database, and Chinese Scientific Journal Database, were used to search articles before January 4, 2021. Eighteen studies with 1,267 participants met the inclusion criteria. All studies reported rates of adherence, ranging from 6.0% to 96.9%. Gastrointestinal intolerances and disliked tastes were considered common barriers to cancer patients' adherence, whereas the ONS management strategy was considered the most crucial facilitator of adherence. Health professionals can improve adherence through regular monitoring and guidance and incentive strategies, and paying attention to the management and prevention of adverse reactions when prescribing nutritional products.
Keywords: adherence; barrier and facilitator factors; cancer; oral nutritional supplements; systematic review.