Phytocannabinoids as Chemotherapy Adjuncts – a User Guide

Simple Summary (148 words) There is increasing evidence, that cannabinoids may play an important and dual role in tumour therapy. On one hand, they are cytotoxic against cancer cells with a low toxicity against normal, healthy tissues, and on the other, they may reduce typical side effects of chemotherapy. Publications on the main motive for use of cannabis (cannabinoids) by cancer patients show that patients' expectations exceed scientific facts. This article briefly describes results of combinations of cannabinoids with standard antineoplastic drugs on tumours and on side effects of tumour therapy. Although observations are still limited to animal studies with very few experiences in patients, preliminary data suggest that adjuvant cannabinoids may improve the survival of glioblastoma and perhaps of patients with other tumours. Benefits have also been reported about chemotherapy-induced nausea and vomiting, chemotherapy-induced peripheral neuropathic pain, loss of appetite and anxiety. Although results are promising, much more research is necessary. Abstract (192 words) Cancer, one of the leading causes of death worldwide, is on the rise. The high toxicity of conventional chemotherapy, often applied as drug cocktails, and resistance development limits the use of anti-neoplastic drugs and reduces the quality of life. With an easier access, a growing number of patients are using cannabis (cannabinoids) for alleviation of their symptoms, and in the hope of improving survival. This narrative article summarizes results observed with combinations of phytocannabinoids and standard chemotherapeutic agents in animal tumour models and in patients. Preliminary data suggest that standard antineoplastic agents combined with cannabinoids exert increased anti-cancer actions, reduce resistance development and improve survival. Respective experiences in patients are still scarce and concern small numbers with glioblastoma, and pancreatic carcinoma. Further benefits of combinations with cannabinoids have also been reported for chemotherapy-induced nausea and vomiting, loss of appetite (dronabinol), chemotherapy-induced peripheral neuropathic pain and anxiety (cannabidiol). In addition, phytocannabinoids, in particular cannabidiol, may play a role in the protection of organs such as heart, lung or kidney against chemotherapy-induced toxicity. Although results are promising, much more research is needed to determine whether positive experiences of adjuvant cannabinoids outweigh eventual risks.