According to the American Cancer Society, breast cancer is the most commonly diagnosed cancer and is the second leading cause of cancer death in American women. Breast cancer screenings and improvement in treatments have resulted in the rising number of survivors in the recent decade. This urged the need for post-diagnosis lifestyle changes to improve breast cancer patients' quality of life. Many studies found soy food, the primary dietary source of phytoestrogens, has a protective effect against breast cancer recurrence and mortality. Dietary phytoestrogens can be classified into two groups: isoflavones and lignans. Daidzein and genistein were identified as the most common isoflavones. Due to their structural similarities to 17- beta estradiol, isoflavones exert agonistic and antagonistic effects. However, limited studies have evaluated the effect of phytoestrogen on health-related quality of life (HRQOL) among cancer survivors. This thesis examined the association between genistein levels and HRQOL and whether these associations are altered by menopausal status using data collected by a research team in South Korea. Women aged 21 to 81 years old, diagnosed with stage I – III primary breast cancer, and received breast cancer surgery at least six months prior were enrolled from five hospitals. Plasma genistein level was measured by orbitrap liquid chromatography-mass spectrometry at the University of Hawaii Cancer Center, Honolulu, Hawaii, U.S.A. HRQOL was self-reported using a validated Korean version of the SF-36 questionnaire. SF-36 has eight domain scores. The scores are summarized into physical (PCS) and mental (MCS) component summary scores, with a higher score indicating better HRQOL. The association between plasma genistein and HRQOL was assessed using a multiple linear regression model adjusting for potential confounders. Stratified analysis was conducted to examine whether menopause status modified this association. 407 women (mean age: 52.1 ± 8.3) with all available data were included in the analysis. The mean blood genistein concentration was 144.7 nM (range: 1.1- 2073.0 nM), and the PCS and MCS scores were 49.5 ± 7.1 and 49.2 ± 9.8, respectively. Analysis for the entire sample showed no significant associations between genistein level and HRQOL score across all domains. Further subgroup analysis by menopausal status revealed that only pre- menopausal women in the highest tertile level of genistein had a higher social function domain score (48.9 vs. 47.2) than those in the lowest tertile with a borderline statistical significance (p = 0.083). These findings suggest beneficial effects of genistein may depend on women's menopausal status, but further investigation is necessary.

Thesis Completion




Thesis Chair/Advisor

Lee, Eunkyung


Bachelor of Science (B.S.)


College of Health and Public Affairs


Health Science



Access Status

Open Access

Release Date