Coenzyme Q10 Studied for Relief of Fatigue in Breast Cancer
Coenzyme Q10 (also called CoQ10) – a naturally occurring compound that helps produce energy in the body’s cells – is being tested for use in relieving fatigue symptoms in breast cancer patients who are undergoing aggressive chemotherapy after surgery.
“We have been interested in the problem of cancer-related fatigue for nearly a decade,” noted the study’s Principal Investigator Glenn Lesser, M.D., Wake Forest University Comprehensive Cancer Center. Wake Forest Cancer Center is designated as a research base for NCI’s Community Clinical Oncology Program (CCOP), focusing on research into symptom management – fatigue, anorexia, and cognitive dysfunction – and cancer prevention and control.
CoQ10 has been previously tested in congestive heart failure and shown to improve cardiac function and improve some of the symptoms experienced with advanced stages of heart failure, including “cardiac fatigue,” Dr. Lesser explained. In addition, small studies have produced data showing that CoQ10 reduces heart damage caused by the anticancer drug doxorubicin.
However, until now there have been no well-designed clinical trials involving large numbers of cancer patients. “CoQ10 is also a well-known agent in the CAM world,” Dr. Lesser continued. “Cancer patients can buy it in health food stores and supermarkets and are taking this agent for its purported benefits for fatigue and for other reasons.”
The study, which began in 2004, has enrolled 202 women who were randomly assigned to receive either CoQ10 (100 mg) or placebo pills 3 times daily for 24 weeks. Both groups also received Vitamin E which increases the absorption of CoQ10. The participants underwent detailed quality-of-life assessments throughout the study period to determine levels of fatigue, depression, and other symptoms.
Dr. Lesser is seeking permission from NCI to reopen the study to enroll an additional 36 patients in part to make up for higher than expected rates of women dropping out of the study. Preliminary data indicate the drop outs were not caused by toxicity or adverse effects of CoQ10, he noted. Instead, patients undergoing aggressive breast cancer treatment often become overwhelmed and frustrated and may decide to forgo the extra burden of an experimental treatment that may not benefit them, he said. In addition, nausea associated with their chemotherapy sometimes causes patients to cut back on taking other oral medications including drugs like CoQ10.
Most participants “were quite attracted to a study like this using a natural compound with some potential or theoretical benefit in conjunction with their more standard chemotherapy,” Dr. Lesser said. If proven effective, CoQ10 “may be an additional strategy to combat the problem of fatigue in breast cancer patients,” he added.
For more information on Coenzyme Q10, please read the PDQ® summary at http://www.cancer.gov/templates/doc.aspx?viewid=0E5B4097-610C-4A49-844F-D935F1D7BB07&version=0.
Phytonutrients Shown to Inhibit Cancer Stem Cells from Regrowing Tumors
Scientists in NCI’s Center for Cancer Research (CCR) are finding early evidence that some phytonutrients – specifically EGCG, a green tea extract, and resveratrol, a compound isolated from grapes and red wine – can inhibit or eliminate cancer stem cells (CSCs) which are increasingly viewed as the driving force behind relapse and chemotherapy resistance in many cancers.
A growing body of evidence has identified CSCs as being the major cause of tumor progression, explained William Farrar, Ph.D., CCR principal investigator for the phytonutrient/chemical study which is supported by OCCAM. CSCs are distinct from the cancer “progeny cells” which are created by CSCs and make up the bulk of most tumors. Current cancer treatments focus on destroying the progeny cells “but in many cases, even after the tumor is reduced or seemingly eliminated, it grows back and becomes resistant to further treatment,” he added. Many researchers now believe that the CSCs often survive initial treatment and act like “evil seeds” that regrow new, more treatment-resistant progeny cells.
Dr. Farrar is head of CCR’s Cancer Stem Cell Section laboratory. One of the initial challenges faced was due to the miniscule numbers of CSCs found in tumors. “The very first time we extracted CSCs we came up with only 280 cells in the sample!” Dr. Farrar recalled. In contrast, high-throughput screening methods typically produce millions of progeny cells for study and analysis. Dr. Farrar and his colleagues focused first on developing tools for extracting and analyzing the small populations of CSCs from tumors.
“Phytochemicals (plant-derived compounds) have a long history demonstrating their cancer preventive properties,” he continued. However, the natural compounds had not been studied specifically for their effects on CSCs until now. Dr. Farrar’s lab winnowed down 22 potential phytochemical compounds “into what I call our short list.” They ultimately decided to first study EGCG and resveratrol in lab cultures of CSCs from breast and prostate cancer tumors and in xenografts of human CSCs.
“The good news is our studies confirm that CSCs are not invulnerable to treatment as some have been concerned,” he reported. Both of the phytochemical compounds were shown to prevent proliferation and block tumor formation by CSCs. They were also effective against cancer progeny cells and did not trigger drug-resistance responses in the tumor cells.
In future studies, Dr. Farrar’s lab will expand its library of phytonutrients and isolate CSCs to determine the effectiveness of phytonutrients for other cancers (i.e., pancreatic, lung, skin).