Detection of a negative correlation between prescription of Chinese herbal products containing coumestrol, genistein or daidzein and risk of subsequent endometrial cancer among tamoxifen-treated female breast cancer survivors in Taiwan between 1998 and 2008: A population-based study.
BACKGROUND
Tamoxifen users sometimes seek complementary and alternative medicine advice for treatment of a variety of illness and co-administer with phytoestrogen-containing herbs, resulting in an increasing concern of its influence in subsequent endometrial cancer risk. Our study aims to determine the prevalence of Chinese herbal products containing coumestrol, genistein, or daidzein and their association with subsequent endometrial cancer risk among tamoxifen-treated breast cancer survivors in Taiwan.


METHODS
We selected all patients who were newly diagnosed with invasive breast cancer and received tamoxifen treatment between January 1, 1998, and December 31, 2008, from the National Health Insurance Research Database. Among the 26,656 tamoxifen-treated breast cancer survivors, we evaluated the usage, frequency of service, and prescription of Chinese herbal products containing coumestrol, genistein, or daidzein. The logistic regression method was employed to calculate the odds ratios for utilization of those herbal products. Cox proportional hazard regression was set to calculate the hazard ratios of endometrial cancer associated with such usage.


RESULTS
Of the patients surveyed, 36.2% (n=9652) of the tamoxifen-treated breast cancer survivors examined in the study had consumed Chinese herbal products containing coumestrol, genistein, or daidzein during the study period. Exposure to Ge Gen(Puerariae Radix) specifically was the most extensive. For it, the population consumed an average cumulative dose of above 180g. Compared to those who had never used Chinese herbal products, breast cancer survivors who had taken Chinese herbal products containing coumestrol, genistein, or daidzein concurrently with tamoxifen treatment did not have a higher hazard ratio for subsequent development of endometrial cancer.


CONCLUSIONS
Among those tamoxifen-treated female breast cancer survivors in Taiwan, consumption of Chinese herbal products containing coumestrol, genistein, or daidzein is negatively correlated with subsequent endometrial cancer risk.
Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Chinese Medicine, China Medical University Hospital, Taipei Branch, Taipei, Taiwan.
Yi-Cheng
YC
Hu
Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Chien-Tung
CT
Wu
Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan; Department of Chinese Medicine, Taipei City Hospital, Yangming Branch, Taipei, Taiwan; Taiwan Association for Traditional Chinese Medicine of Family, Taiwan. Electronic address: kareny@ms10.hinet.net.
Jung-Nien
JN
Lai
Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
Yueh-Ting
YT
Tsai
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000453:epidemiology; D016022:Case-Control Studies; D003375:Coumestrol / Q000009:adverse effects* / Q000627:therapeutic use; D004365:Drugs, Chinese Herbal / Q000009:adverse effects*; D016889:Endometrial Neoplasms / Q000139:chemically induced* / Q000453:epidemiology*; D005260:Female; D019833:Genistein / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D007529:Isoflavones / Q000009:adverse effects* / Q000627:therapeutic use; D008875:Middle Aged; D017741:Survivors / Q000706:statistics & numerical data; D013624:Taiwan / Q000453:epidemiology; D013629:Tamoxifen / Q000627:therapeutic use*; D055815:Young Adult
D004365:Drugs, Chinese Herbal; D007529:Isoflavones; D013629:Tamoxifen; C004742:daidzein; D019833:Genistein; D003375:Coumestrol
Breast cancer; Chinese herbal product; Coumestrol; Daidzein; Genistein; Herb-drug interaction; National health insurance research database; Phytoestrogen; Tamoxifen