Dietary intake of isoflavones and breast cancer risk by estrogen and progesterone receptor status

Abstract

Epidemiological and experimental studies suggest that isoflavones may protect against breast cancer by acting as estrogen agonists or antagonists. A case-control study was conducted in southeast China in 2004-2005 to examine the association between dietary isoflavone intake and breast cancer risk by estrogen receptor (ER) and progesterone receptor (PR) status. The incident cases were 756 female patients with histologically confirmed breast cancer. The 1,009 age-matched controls were healthy women randomly recruited from outpatient breast clinics. We assessed isoflavone intake by face-to-face interview using a validated and reliable food-frequency questionnaire and obtained tumor ER and PR status from pathologic reports. Compared with women in the lowest intake quartiles, those in the highest quartile of total isoflavone intake had a reduced risk of all receptor status subtypes of breast cancer with a dose-response relationship. The adjusted ORs (95% CIs) were 0.39 (0.27-0.58) for ER+, 0.32 (0.21-0.49) for ER-, 0.43 (0.29-0.64) for PR+, and 0.30 (0.19-0.45) for PR- (P for trend <0.001). These inverse associations existed in both pre- and post-menopausal women after stratification. Stronger evidence of a protective effect of high isoflavone intake was observed for breast cancer tumors with concordant rather than discordant receptor status; i.e., those with ER+/PR+ (OR 0.39, 0.26-0.59) and ER-/PR- (OR 0.28, 0.17-0.44). The finding that isoflavones protect against all tumor subtypes of breast cancer have biological plausibility, being supported by evidence from experimental studies. Future studies are required to fully understand the complex regulation of isoflavone on breast cancer by tumor hormone status.

Effect of dietary soy intake on breast cancer risk according to menopause and hormone receptor status

“…Several epidemiological studies have examined the effect of soy intake with stratification by receptor status but reported mixed findings. A case-control study in China found that a greater risk reduction was associated with ERÀ/PRÀ tumors than with ER þ /PR þ tumors (Zhang et al, 2009). However, another case-control study in China found that the protective effect of soy protein intake on breast cancer risk was stronger with ER þ /PR þ receptor status than for other subtypes (Dai et al, 2001).…”

“…However, the association between soy consumption and breast cancer risk remains inconclusive in epidemiological studies (Trock et al, 2006;Wu et al, 2008b). It has been suggested that the effect of soy consumption on breast cancer etiology may depend on several factors, including hormonal environment (Yamamoto et al, 2003;Hirose et al, 2005;Hwang et al, 2006), receptor status (Linseisen et al, 2004;Suzuki et al, 2008;Zhang et al, 2009), timing of soy exposure (Wu et al, 2002), amount and profile of isoflavones in foods or supplements (Hsieh et al, 1998), and individual metabolism and genetics (Setchell et al, 2002).…”

Fish, n − 3 polyunsaturated fatty acids and n − 6 polyunsaturated fatty acids intake and breast cancer risk: The Japan Public Health Center‐based prospective study

“…Inconsistent results of previous studies may be due to the variations in breast tumor subtype (ER PR status) given that previous laboratory 19 and epidemiological studies [20][21][22] have found significant associations between breast cancer according to subtype and different exposures including body size and diet. While a multiethnic cohort study with hormone receptor status analysis on postmenopausal women showed no significant association of n 2 3 PUFA and n 2 6 PUFA intake with breast cancer risk, 22 other hormonal studies have…”

Hospital Outpatients are Satisfactory for Case-control Studies on Cancer and Diet in China: A Comparison of Population Versus Hospital Controls

“…The structured questionnaire, available from the authors upon request, was used to collect the information on: (i) demographic and lifestyle characteristics, e.g., area of residence, education, smoking, alcohol and tea consumption and physical activity; (ii) habitual dietary intakes assessed by a 119-food frequency questionnaire (FFQ); and (iii) factors relevant to hormonal status and family history of cancer. The questionnaire was adapted from that used in our previous studies on cancers (Zhang et al, 2009). This instrument was originally modified from one used for studying cancers in Shanghai in order to ensure cultural relevance (Ji et al, 1998).…”