Positive Effects of Soy Isoflavone Food on Survival of Breast Cancer Patients in China

Abstract

Aim: Soy foods are the major source of isoflavones, which are believed to play important roles in genesis of breast cancer and its progression. We here conducted a prospective study to evaluate the association of soy isoflavone food consumption with breast cancer prognosis. Methods: A prospective study was performed from January 2004 and January 2006 in China. Trained interviewers conducted face-to-face interviews using a structured questionnaire to collect information on dietary habits and potential confounding factors. The relative risk [hazard ratio (HR)] and 95% CI were calculated from the Cox regression model for all significant predictors from cancer diagnosis to the endpoint of the study (event). Results: After a median follow up of 52.1 months (range, 9-60 months), a total of 79 breast cancer related deaths were recorded in our study, risk being inversely associated with a high intake of soy isoflavone. With an average intake of soy isoflavone above 17.3 mg/day, the mortality of breast cancer can be reduced by about 38-36%. We also found the decreased breast cancer death with high soy protein intake, with a HR (95% CI) of 0.71 (0.52-0.98). Stratified analysis with reference to the ER status, further demonstrated a better prognosis of ER positive breast cancer with a high intake of soy isoflavone (HR 0.59, 0.40-0.93). Conclusion: Our study shows the soy food intake is associated with longer survival and low recurrence among breast cancer patients. A cohort study with a larger sample size and long term follow-up is now needed.

Post-diagnosis Soy Food Intake and Breast Cancer Survival: A Meta-analysis of Cohort Studies

“…And another study conducted by Fink et al (Fink et al, 2007) reported that reduced hazard ratios [hazard ratio (95% confidence interval)] for all-cause mortality were observed among premenopausal and postmenopausal women for the highest quintile of intake prior to cancer diagnosis, compared with the lowest, for isoflavones [0.52 (0.33-0.82)]. Regarding to the associations between soy food intake after cancer diagnosis and survival (mortality or recurrence), the results were not the same based on available cohort studies (Guha et al, 2009;Shu et al, 2009;Kang et al, 2010;Caan et al, 2011;Nechuta et al, 2012;Zhang et al, 2012). One meta-analysis of four prospective cohort studies (Boyapati et al, 2005;Fink et al, 2007;Guha et al, 2009;Shu et al, 2009) showed that soy isoflavones intake was inversely associated with risk of breast cancer recurrence (Dong et al, 2011).…”

“…After reading full-texts, we excluded reviews (n =47), experimental studies (n =88) and not about survival (n=41). Finally, five cohort studies (six citations (Guha et al, 2009;Shu et al, 2009;Kang et al, 2010;Caan et al, 2011;Nechuta et al, 2012;Zhang et al, 2012)) (11206 patients) were included.…”

“…It is reported that soy food might have the potential cancer inhibitory effect in breast cancers expressing oestrogen receptor (Zhang et al, 2012). Recent metaanalyses (Qin et al, 2006;Trock et al, 2006;Enderlin et al, 2009;Dong et al, 2011) showed that soy isoflavones intake was associated with a reduced risk of breast cancer incidence.…”

“…About 1.38 million new cases of breast cancer among women were estimated to have occurred in 2008, making it currently the second most common malignant among women worldwide (Zhang et al, 2012). It was estimated that 192,370 women would be diagnosed with and 40,170 women would die of cancer of the breast in 2009 (Li et al, 2010).…”

Vascular Endothelial Growth Factor (VEGF) Gene Polymorphisms and Breast Cancer Risk in a Chinese Population

“…The mechanism of breast carcinogenesis is still not fully understood. Breast cancer may result from multiple environmental, dietary, hereditary, racial and socioeconomic risk factors (Ronco et al, 2012a;Ronco et al, 2012b;Zhang et al, 2012;Zhou et al, 2012a;Zhou et al, 2012b;Shamsi et al, 2013;Sun et al, 2013).…”