Adverse events associated with the use of cannabis-based products in people living with cancer: a systematic scoping review.

Purpose: To summarise the extent and type of evidence in relation to adverse events (AEs) associated with the use of cannabis-based products (CBP) in people living with cancer.

Methods: The Joanna Briggs Institute (JBI) methodology for scoping reviews was applied. A search was performed in MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCOhost), Scopus, Web of Science Core Collections and AMED (Ovid) from their inception to 7 May 2023. Primary studies reporting AEs associated with any form of natural or synthetic CBP use in any cancer care setting and location were included.

Results: One hundred fifty-two studies were included, with the most prevalent being randomised controlled trials (RCTs) (n = 61), followed by non-randomised controlled trials (n = 26) and case reports (n = 23). CBP was mainly used in gastrointestinal, liver, or peritoneal cancer (n = 98) and haematological or lymphoid cancer (n = 92), primarily to manage nausea and vomiting (n = 78) and cancer pain (n = 37). The most common CBP ingredients were combinations of THC and CBD (n = 69), synthetic THC (n = 47), single compounds of THC (n = 42) and CBD (n = 16) with diverse forms, administration routes and doses. The primary methods of administration were oral (n = 94) and inhalation (n = 54). A broad range of AEs were reported; the most common were related to the nervous system (n = 118), psychiatric (n = 101) and gastrointestinal system (n = 81). Diverse patient characteristics, significant under-reporting and low-quality reporting were observed in many studies.

Conclusions: More rigorous research designs that prioritise comprehensive, standardised reporting of AEs and CBP use are required to fully elucidate the safety profile of CBP use in cancer care.