Abstract
Background and ObjectivesMany studies have shown a negative association between the consumption of soy products and the risk of some cancers, but little is known about the effect of soy consumption on nasopharyngeal carcinoma. We assessed the association between the consumption of soy products on nasopharyngeal carcinoma risk in Chinese individuals.MethodsThis case-control study included 600 (448 males and 152 females) incident cases of nasopharyngeal carcinoma, and an equal number of controls, matched according to gender, age (± 3 y) and household type to the nasopharyngeal carcinoma cases. All subjects were recruited from hospitals in Guangzhou, China. A face-to-face interview was conducted with each study individual to collect general information and habitual dietary intake using a 78-item quantitative food-frequency questionnaire. Odds ratios and their 95% confidence intervals were estimated using conditional logistic regression analyses.ResultsThe median intakes of soy foods (in protein) were 0.5/0.5, 1.4/1.7, 2.7/3.3 and 6.1/7.7 (male/female) g/d in the quartiles 1 to 4. Both univariate and multivariate analyses showed no significant association between the consumption of soy proteins or soy isoflavones and the risk of nasopharyngeal carcinoma. The adjusted odds ratios (95% confidence intervals) between extreme quartiles were 0.97 (0.66-1.45) for soy proteins and 0.97 (0.66-1.42) for total isoflavones. Null associations were also observed between intake of the individual isoflavones daidzein, genistein and glycitein and NPC risk, with adjusted odds ratios for the extreme quartiles ranging between 0.73 and 1.23.ConclusionHabitual consumption of soy products had no significant effect on the risk of nasopharyngeal carcinoma in Chinese adults with a relatively low intake.
Highlights
South China has a much higher incidence of nasopharyngeal carcinoma (NPC, 20 per 105 males and 7 per 105 females per year) compared with the rest of the world (1.7 per 105 persons per year) [1]
odds ratios (OR) from subsequent analyses of the 358 and 242 case-control pairs with matched and unmatched educational levels, respectively, were generally similar to those from the whole data set. (Table 3). In this matched case-control study with 600 pairs of incident Nasopharyngeal carcinoma (NPC) cases and controls, we found no significant protective effects of soy proteins or total or individual soy isoflavones on NPC, either overall or across groups of gender, household type, TNM stage and education level
A large number of epidemiological studies observed favorable effects of soy products on breast [7], prostate [6], lung [18] and colorectal cancer [8], few studies have examined the association between soy products and NPC risk, and the results in these latter studies are conflicting
Summary
South China has a much higher incidence of nasopharyngeal carcinoma (NPC, 20 per 105 males and 7 per 105 females per year) compared with the rest of the world (1.7 per 105 persons per year) [1]. In the limited number of published studies that investigated a few specific soy products (tofu [11] and fermented soybean products [7]), no association was found between the intake of soy products and the risk of developing NPC. A face-to-face interview was conducted with each study individual to collect general information and habitual dietary intake using a 78-item quantitative food-frequency questionnaire Odds ratios and their 95% confidence intervals were estimated using conditional logistic regression analyses. Results: The median intakes of soy foods (in protein) were 0.5/0.5, 1.4/1.7, 2.7/3.3 and 6.1/7.7 (male/female) g/d in the quartiles 1 to 4 Both univariate and multivariate analyses showed no significant association between the consumption of soy proteins or soy isoflavones and the risk of nasopharyngeal carcinoma. Conclusion: Habitual consumption of soy products had no significant effect on the risk of nasopharyngeal carcinoma in Chinese adults with a relatively low intake
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