Low Plasma Coenzyme Q10 Levels and Breast Cancer Risk in Chinese Women

Abstract

Background Low circulating levels of Coenzyme Q10 (CoQ10) have been associated with increased cancer incidence and poor prognosis for a number of cancer types, while a recent prospective study observed a positive association for CoQ10 with breast cancer risk. Methods We prospectively examined the association of plasma CoQ10 with breast cancer risk in a nested case-control study of Chinese women within the Shanghai Women's Health Study (SWHS). Pre-diagnostic plasma samples were obtained from 340 cases and 653 age-matched controls and analyzed for total CoQ10. Results A borderline significant inverse association for breast cancer incidence with plasma CoQ10 level was observed using a conditional logistic regression model adjusted for age and age at first live birth, which became significant after elimination of cases diagnosed within one year of blood draw (ptrend = 0.03). This association was independent of menopausal status. Plasma CoQ10 levels were also observed to be significantly associated with circulating γ-tocopherol (r = 0.50; p < 0.0001) and with α-tocopherol (r =0.38; p < 0.0001) levels. Conclusions Circulating levels of CoQ10 were generally low in this population and the observed association with breast cancer risk may be limited to those women with exceptionally low values. Impact This study reports an inverse relationship between circulating CoQ10 and breast cancer risk, while the only other prospective study of CoQ10 and breast cancer to date found a positive association. Lower levels of CoQ10 in the SWHS population suggests that the two studies may not be contradictory and indicates a possible non-linear (U-shaped) association of CoQ10 with risk.

Role of Coenzyme Q10 in Breast Cancer

“…In a nested control case-control study by Cooney et al [5], the association of plasma CoQ10 with breast cancer risk on Chinese women was examined. For the analysis 340 cases and 653 controls were selected.…”

“…After stratifying the data for different patient characteristics, the only one that was statistically significant was for patients on the highest tertile of CoQ10 levels with tocopherol levels below the median. When comparing the multiethnic cohort with the Chinese cohort, the CoQ10 levels were lower in Chinese women [5][6][7][8][9][10] This maybe due to the fact that the multiethnic cohort included only women from 45-75 years old, which are postmenopausal, while Chinese cohort included premenopausal and postmenopausal Thus, CoQ10 levels vary depending on ethnicity and menopausal status. Jolliet et al [7] also measured the CoQ10 plasma concentration in patients with malignant tumors and benign lesions.…”

“…However, the levels of CoQ10 do not necessarily correlate to tochopherol levels. Cooney et al found a linear correlation of CoQ10 and tocopherol, while Jolliet et al found no correlation between CoQ10 levels and tocopherol levels, when comparing healthy subjects to patients with malignant and non-malignant breast tumors [5,7]. Tamoxifen (TAM) has been shown to be effective, not just as an adjuvant therapy after surgery, chemo or radiation therapy in early and advanced breast cancer cases, but also in chemoprevention in high-risk pre-and postmenopausal women.…”

Coenzyme Q10 therapy in current clinical practice

“…5 CoQ 10 is a key molecule in all energy requiring processes, including immune function, angiogenesis, proliferation, and apoptosis, suggesting the potential of CoQ 10 for initiation and progression of cancer. 6 Despite the critical role of CoQ 10 in many cellular functions and gene expression, its potential relationship with many of the diseases and cancer development and progression has not received appropriate attention. Epidemiological or clinical studies of plasma or tissue CoQ 10 involve limited numbers of subjects and are rare in the literature.…”

“…Epidemiological or clinical studies of plasma or tissue CoQ 10 involve limited numbers of subjects and are rare in the literature. 1,4,6 This review intends to critically analyze the role of CoQ 10 (if any) in current clinical medical practice. Table 1 shows the mechanism of action at biochemical level, 2 molecular level 1 and level at drug induced apoptosis.…”