A Scoping Review: Clinical Trials Assessing Turmeric Dietary Supplement Use in Cancer

Abstract

Turmeric, one of the top selling botanicals in the United States, has been identified by our research group as the top botanical dietary supplement used by women diagnosed with breast cancer (22%, n = 1,224), with health care providers, family/friends and social media all being frequently reported sources of information regarding its use. However, some scientists have questioned whether curcumin(oids), the primary turmeric-derived component in these supplements, have medicinal benefits, in part due to their poor bioavailability, despite a history of medicinal turmeric use for thousands years in Ayurvedic medicine. A scoping review of the literature was therefore undertaken to identify clinical trials investigating the validity of oral curcumin-containing turmeric DS. Using a defined search strategy, eight databases were reviewed (thru 5/29/2019), identifying n =4767 potential reports for inclusion, from which only n = 315 remained after review by three independent observers. Cancer was among the most commonly studied disorders (n = 40), which also included disorders of glucose and lipid metabolism (n = 69), musculoskeletal disorders (n= 50), and gastrointestinal and hepatic disorders (n = 50). Prostate (n = 8), gastrointestinal (n = 11), and breast (n = 6) were among the most commonly studied cancers. In addition to differences and some weaknesses in study design, the variability and, in some cases, a lack of clarity as to the composition of the natural products tested make it difficult to derive solid conclusions related to clinical use for oncology. Despite these limitations, most oncologic and non-oncologic clinical trials reported significant physiologic effects. Reduced HER2 serum levels; reduced serum/urine protein, paraprotein, and creatinine levels in patients with myelomatous disease; reduced urinary symptoms in prostate cancer patients; reduced inflammatory markers; and improved quality of life in an array of malignant neoplastic syndromes are among some of the findings in these clinical studies. In addition, curcumin also caused increased muscle and adipose tissue wasting in cachexic patients with pancreatic cancer. These varying results, both positive and negative, combined with the popularity of curcumin DS in the United States, including by women with breast cancer, provide evidence that further large, well-designed human trials should not be abandoned. This is particularly true for oncologic populations at higher risk of possible untoward effects related to drug-supplement interactions.