The golden spice curcumin in cancer: A perspective on finalized clinical trials during the last 10 years

Curcumin, the key bioactive phytochemical present in turmeric (Curcuma longa L.), is the most studied natural compound in cancer. Preclinical studies (in vitro and in vitro) and clinical trials have demonstrated curcumin's effectiveness as an anti-inflammatory agent. The existing evidence supports that curcumin inhibits the proliferation of many types of cancer cells and can play an important role in cancer therapy. This study analyses the existing evidence in the literature on finalized clinical trials (2010-2020) related to the effect of curcumin and turmeric-derived products that focused on different types of cancers, such as chronic myeloid leukemia, multiple myeloma, prostate, colorectal and pancreatic cancer as well as cancer therapy-related complications, including oral mucositis and radiation dermatitis. Original English language articles and clinical trials published between 2010 and 2020 were searched using mainstream scholarly databases, such as PubMed, ScienceDirect, Google Scholar, and ClinicalTrials.gov. The keywords, such as "curcumin," "turmeric," "cancer," "anti-inflammatory," and "clinical trials," were used in various combinations. A total of 21 clinical trials were selected, reviewed, and included in this study. Sixteen out of 21 clinical trials were associated with the effectiveness of curcumin or turmeric on various types of cancer, and the other five clinical trials were related to the evaluation of the efficacy of curcumin or turmeric in relieving the side effects of cancer chemotherapy and radiotherapy. The emerging data from the clinical trials confirm that curcumin has the potential for cancer prevention and intervention. However, it is not yet clear whether long-term curcumin supplementation has similar benefits.