Soy food intake and risk of lung cancer: evidence from the Shanghai Women's Health Study and a meta-analysis

Soy Product Consumption and the Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies

BACKGROUND

The association between soy product consumption and cancer risk varies among studies. Therefore, this comprehensive meta-analysis of observational studies examines the association between soy product consumption and total cancer risk.

METHODS

This study was conducted following the PRISMA guidelines. Up to October 2023, all eligible published studies were searched through PubMed and Web of Science databases.

RESULTS

A total of 52 studies on soy product consumption were included in this meta-analysis (17 cohort studies and 35 case-control studies). High consumption of total soy products (RR: 0.69; 95% CI: 0.60, 0.80), tofu (RR: 0.78; 95% CI: 0.70, 0.86), and soymilk (RR: 0.75; 95% CI: 0.60, 0.93) were associated with reduced total cancer risk. No association was found between high consumption of fermented soy products (RR: 1.18; 95% CI: 0.95, 1.47), non-fermented soy products (RR: 0.95; 95% CI: 0.77, 1.18), soy paste (RR: 1.00; 95% CI: 0.88, 1.14), miso soup (RR: 0.99; 95% CI: 0.87, 1.12), or natto (RR: 0.96; 95% CI: 0.82, 1.11) and cancer risk. A 54 g per day increment of total soy products reduced cancer risk by 11%, a 61 g per day increment of tofu reduced cancer risk by 12%, and a 23 g per day increment of soymilk reduced cancer risk by 28%, while none of the other soy products were associated with cancer risk.

CONCLUSION

Our findings suggest that high total soy product consumption, especially soymilk and tofu, is associated with lower cancer risk. More prospective cohort studies are still needed to confirm the causal relationship between soy product consumption and cancer risk.

Vitamin K Intake and Risk of Lung Cancer: The Japan Collaborative Cohort Study

BACKGROUND

Limited reports from prospective human studies investigated the possible role of vitamin K in the development of lung cancer although vitamin K's anticarcinogenic activities were verified from several in vitro and in vivo studies. We investigated the associations between total vitamin K intake from food and the development of lung cancer based on this large prospective cohort study.

METHODS

A validated food frequency questionnaire was used to examine vitamin K intake among 42,166 (16,341 men and 25,825 women) at the Japan Collaborative Cohort Study's baseline (1988-1990). Hazard ratios (HRs) and 95% confidence intervals (CIs) of incident lung cancer were calculated using the Cox proportional hazard regression method based on vitamin K consumption quartiles.

RESULTS

430 cases (308 males and 122 women) of lung cancer were documented during a total of 564,127 person-years of follow-up (median follow-up, 14.6 years). Vitamin K consumption was shown to be inversely related to lung cancer risk; the multivariable hazard ratio [HR] for the highest versus lowest quartiles was 0.67 (95% confidence interval [CI], 0.46-0.96; P for trend = 0.010). This relationship appears to be stronger in males (HR 0.62; 95% CI, 0.40-0.96; P for trend = 0.016) than in females (HR 0.82; 95% CI, 0.42-1.61; P for trend = 0.39) (P for interaction = 0.012), and in ever smokers (HR 0.57; 95% CI, 0.36-0.91; P for trend = 0.006) than in never smokers (HR 0.79; 95% CI, 0.40-1.55; P for trend = 0.37) (P for interaction = 0.30). The individuals' age, body mass index, or alcohol consumption status had no effect on the observed connection.

CONCLUSION

Vitamin K consumption reduces the risk of lung cancer. More research is needed to clarify the molecular processes behind this connection.

Calcium Intake and Lung Cancer Risk: A Pooled Analysis of 12 Prospective Cohort Studies

BACKGROUND

Previous studies on calcium intake and lung cancer risk reported inconsistent associations, possibly due to the differences in intake amounts and contributing sources of calcium and smoking prevalence.

OBJECTIVES

We investigated the associations of lung cancer risk with intake of calcium from foods and/or supplements and major calcium-rich foods in 12 studies.

METHODS

Data from 12 prospective cohort studies conducted in the United States, Europe, and Asia were pooled and harmonized. We applied the DRI to categorize calcium intake based on the recommendations and quintile distribution to categorize calcium-rich food intake. We ran multivariable Cox regression by each cohort and pooled risk estimates to compute overall HR (95% CI).

RESULTS

Among 1,624,244 adult men and women, 21,513 incident lung cancer cases were ascertained during a mean follow-up of 9.9 y. Overall, the dietary calcium intake was not significantly associated with lung cancer risk; the HRs (95% CI) were 1.08 (0.98-1.18) for higher (>1.5 RDA) and 1.01 (0.95-1.07) for lower intake (<0.5 RDA) comparing with recommended intake (EAR to RDA). Milk and soy food intake were positively or inversely associated with lung cancer risk [HR (95% CI) = 1.07 (1.02-1.12) and 0.92 (0.84-1.00)], respectively. The positive association with milk intake was significant only in European and North American studies (P-interaction for region = 0.04). No significant association was observed for calcium supplements.

CONCLUSIONS

In this largest prospective investigation, overall, calcium intake was not associated with risk of lung cancer, but milk intake was associated with a higher risk. Our findings underscore the importance of considering food sources of calcium in studies of calcium intake.

Isoflavone and soy food intake and risk of lung cancer in never smokers: report from prospective studies in Japan and China

PURPOSE

Evidence from several cohorts has suggested that a higher intake of isoflavone is associated with lower risk of lung cancer in never smokers, but the association has not been investigated by histologic type of lung cancer. Adenocarcinoma is a common histologic type found in never smokers. We hypothesized that a higher intake of isoflavone is associated with a lower risk of lung adenocarcinoma among never smokers. Here, we examined the associations of isoflavone and soy food intake with lung cancer and its histologic types in never smokers.

METHODS

We performed a pooled analysis using data from the Japan Public Health Center-based Prospective Study, Shanghai Women's Health Study and Shanghai Men's Study with 147,296 never smokers aged 40-74 years with no history of cancer. During 1,990,040 person-years of follow-up, 1247 lung cancer cases were documented. Dietary isoflavone and soy food intake were assessed using a food-frequency questionnaire. Multivariable Cox proportional hazards models assessed the associations between isoflavone and soy intake with incidence of lung cancer by histologic type.

RESULTS

A higher intake of dietary isoflavone and soy food were associated with reduced risk of lung adenocarcinoma. The multivariable hazard ratios (HRs) (95% CI) of risk of lung adenocarcinoma for the highest versus lowest intakes of isoflavone and soy food were 0.74 (0.60-0.92) and 0.78 (0.63-0.96), respectively. The multivariable HRs of risk of lung adenocarcinoma associated with each 10 mg/day increase in isoflavone and each 50 g/day increase in soy food intake were 0.81 (0.70-0.94) and 0.84 (0.73-0.96), respectively.

CONCLUSION

Higher intake of isoflavone and soy food was associated with lower risk of lung adenocarcinoma in never smokers.

Intake of Soy, Soy Isoflavones and Soy Protein and Risk of Cancer Incidence and Mortality

Background and Aims

Associations between soy intake and risk of cancer have been evaluated in prospective observational studies with inconsistent results. Whether the potential anticancer effects offered by soy were attributed to soy isoflavones and soy protein still needs to be elucidated. This study aimed to comprehensively quantify the association of soy, soy isoflavones and soy protein intake with risk of cancer incidence and cancer mortality by conducting a meta-analysis of all available studies.

Methods

PubMed, Embase, Web of Science, and Cochrane Library databases were searched up to 16 September 2021. Prospective cohort studies that examined the effect of soy, soy isoflavones and soy protein on cancer incidence and cancer mortality were identified. Random-effects models were used to pool the multivariable-adjusted relative risks (RRs) and corresponding 95% confidence intervals (CIs). The potential dose-response relations were explored by using generalized least-squares trend estimation.

Results

Eighty one prospective cohort studies were included in the meta-analysis. A higher intake of soy was significantly associated with a 10% reduced risk of cancer incidence (RR, 0.90; 95% CI, 0.83–0.96). Each additional 25 g/d soy intake decreased the risk of cancer incidence by 4%. Intake of soy isoflavones was inversely associated with risk of cancer incidence (RR, 0.94; 95% CI, 0.89–0.99), whereas no significant association was observed for soy protein. The risk of cancer incidence was reduced by 4% with each 10 mg/d increment of soy isoflavones intake. Similar inverse associations were also found for soy in relation to site-specific cancers, particularly lung cancer (RR, 0.67; 95%CI, 0.52–0.86) and prostate cancer (RR, 0.88; 95%CI, 0.78–0.99). However, high intake of soy, soy isoflavones and soy protein were not associated with cancer mortality.

Conclusions

Higher intake of soy and soy isoflavones were inversely associated with risk of cancer incidence, which suggested that the beneficial role of soy against cancer might be primarily attributed to soy isoflavones. These findings support recommendations to include soy as part of a healthy dietary pattern for the prevention of cancer.

Phytoestrogens and lung cancer risk: a nested case-control study in never-smoking Chinese women

BACKGROUND

Since several lines of evidence suggest that estrogens may be involved in lung carcinogenesis, it has been hypothesized that intake of phytoestrogens, similar in molecular structure to mammalian estrogens, may be associated with lung cancer development.

OBJECTIVE

The aim was to prospectively evaluate the association between phytoestrogen exposure and lung cancer risk in never-smoking women.

METHODS

We conducted a nested case-control study within a population-based prospective cohort study of women. A total of 478 incident lung cancer cases and their individually matched controls were identified among never-smoking women after a mean follow-up of 15.6 years. Habitual intake of and internal exposure to phytoestrogens were assessed by repeated dietary surveys and urinary biomarkers, respectively. ORs and 95% CIs for lung cancer were estimated in conditional logistic regression models.

RESULTS

After adjustment for potential confounders, a moderate intake of dietary isoflavones was inversely associated with lung cancer risk in never-smoking women, with the OR for the second quartile vs. the lowest quartile of intake being 0.52 (95% CI: 0.35, 0.76). Further increasing intake did not convey additional benefits, with ORs (95% CI) for the third and fourth quartiles of 0.53 (0.36, 0.78) and 0.47 (0.31, 0.72), respectively (P-overall < 0.001 and P-nonlinearity = 0.006). A similar association was seen when exposure to isoflavones was assessed by urinary biomarkers. ORs (95% CI) for the second, third, and fourth quartiles compared with the lowest quartile of urinary isoflavone excretion were 0.57 (0.39, 0.83), 0.64 (0.44, 0.92), and 0.60 (0.41, 0.86), respectively. The inverse association reached a plateau beyond the second quartile, with P-overall = 0.04 and P-nonlinearity = 0.15. Urinary excretion of gut-microbiota-derived metabolites of lignans was not related to lung cancer risk.

CONCLUSIONS

This study suggests that moderately increasing intake of isoflavone-rich foods is associated with lower risk of lung cancer in never-smoking women.

Microarray analysis of differentially expressed long non-coding RNAs in daidzein-treated lung cancer cells

Daidzein has been found to significantly inhibit the proliferation of lung cancer cells, while its potential molecular mechanisms remain unclear. To determine the molecular mechanism of daidzein on lung cancer cells, the Capital Bio Technology Human long non-coding (lnc) RNA Array v4, 4×180K chip was used to detect the gene expression profiles of 40,000 lncRNAs and 34,000 mRNAs in a human cancer cell line. Reverse transcription-quantitative (RT-q) PCR analysis was performed to detect the expression levels of target lncRNA and mRNAs in the H1299 cells treated with and without daidzein, using the lncRNA and mRNA gene chip. Bioinformatics analysis was performed to determine the differentially expressed genes from the results of the chip assays. There were 119 and 40 differentially expressed lncRNAs and mRNAs, respectively, that had a 2-fold change in expression level. A total of eight lncRNAs were upregulated in the H1299 lung cancer cells, while 111 lncRNAs were downregulated. Furthermore, five mRNAs were upregulated, and 35 mRNAs were downregulated. A total of six differentially expressed lncRNAs (ENST00000608897.1, ENST00000444196.1, ENST00000608741.1, XR_242163.1, ENST00000505196.1 and ENST00000498032.1) were randomly selected to validate the microarray data, which were consistent with the RT-qPCR analysis results. Differentially expressed mRNAs were enriched in important Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways. Taken together, the results of the present study demonstrated that daidzein affected the expression level of lncRNAs in lung cancer cells, suggesting that daidzein may have potential effects on lung cancer cells.

Menstrual factors, reproductive history, and risk of lung cancer: a multi-center population-based cohort study in Chinese females

BACKGROUND

Female menstrual and reproductive factors, as remarkable indicators of hormone effect, were hypothesized to be associated with lung cancer risk, whereas the existed epidemiological evidence was inconsistent. Our study aims to investigate the association between menstrual and reproductive factors and lung cancer risk based on the Chinese Lung Cancer Screening Program.

METHODS

This study was based on a large-scale multi-center population cohort across China recruiting individuals aged 40-74 years old between 2013-2018. Cox regression model was applied to estimate the HRs and 95% CIs. Restricted cubic spline (RCS) analysis was used to estimate dose-response relationships and test for nonlinear associations.

RESULTS

Among 553,434 female participants, 1,529 incident lung cancer cases were identified with a median follow-up of 3.61 years. With adjustment for multiple covariates and all significant hormonal factors, elevated lung cancer risk was associated with later age (15, or ≥16 years) at menarche (HR =1.27, 95% CI: 1.04-1.56; HR =1.45, 95% CI: 1.19-1.76), later age (25-29, or ≥30 years) at first live birth (HR =1.27, 95% CI: 1.13-1.43; HR =1.23, 95% CI: 1.00-1.51), and benign breast disease history (HR =1.25, 95% CI: 1.10-1.41). For postmenopausal females specifically, surgical menopause (HR =1.62; 95% CI: 1.29-2.05) and other surgeries on the reproductive system (HR =1.19; 95% CI: 1.01-1.40) both appeared to be predictive of elevated lung cancer risk. Concerning age at menopause, a nonlinear association was observed (P-nonlinear =0.0126). Increased lung cancer risk was observed among females with age at menopause especially above 50. Although we observed no significant associations between longer time (≥13 months) of breastfeeding and lung cancer risk among all participants (HR =0.86; 95% CI: 0.71-1.04), significant decreased adenocarcinoma risk (HR =0.65; 95% CI: 0.53-0.81) was noted among nonsmoking females.

CONCLUSIONS

Our findings add some support for the role of menstrual and reproductive factors in lung carcinogenesis. However, these relationships were complex, and required further investigations addressing the biological mechanisms.

Dietary phytoestrogen intake and lung cancer risk: an analysis of the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial

Phytoestrogens (PEs) have estrogen-like activity and were found to lower incidences of several hormone-dependent cancers. Emerging evidence suggests that estrogen may play a role in lung cancer carcinogenesis. We aim to evaluate dietary PE intake and lung cancer risk using data from the Prostate, Lung, Colorectal, and Ovarian cancer screening trial. A total of 1,706 lung cancer cases were identified. The association between lung cancer risk and PE intake (in quartiles) was calculated using the Cox proportional hazard models adjusting for potential confounders. Stratified analyses by smoking status, sex, and histology were also performed. The highest quartile of total PE intake was associated with a reduced risk of lung cancer compared to the lowest quartile (HR=0.85, 95%CI: 0.73-0.99 for > 1,030 μg/day vs < 290 μg/day) (P trend=0.56). Similar patterns were observed among ever smokers (HR=0.84, 95%CI: 0.71-0.98), non-small cell histology (HR=0.84, 95CI: 0.72-0.99), male (HR=0.84, 95%CI: 0.69-1.03) and female (HR=0.80, 95%CI: 0.64-0.99 for 510-1,030 μg/day, HR=0.84, 95%CI: 0.67-1.06 for > 1,030 μg/day vs < 290 μg/day) subjects with no significant linear trend observed. Despite a lower consumption compared to the Asian population, increased PE intake still appears to decrease lung cancer risk in a Caucasian-dominant population. Future studies are needed to replicate these results in independent cohorts and shed a light on the potential mechanism of the protective effect of PEs on lung carcinogenesis and the interaction between PEs, smoking, and endogenous estrogens.

Association of various dietary habits and risk of lung cancer: an updated comprehensive literature review

Lung cancer remains the leading cause of cancer death in both men and women worldwide. Tobacco smoking remains the single most important factor. Recent research has focused on the role of nutrition and dietary habits on lung tumorigenesis. With many individual reports on separate dietary aspects, no single review is available in the literature that summarizes the updated studies. To our knowledge, this is the first review that comprehensively reviews the updated literature on the effect of dietary habits on lung cancer. This review was concluded in February 2019 and included all meta-analyses, systematic reviews, and literature reviews. Thirty studies were retrieved in total. Items in the diet that offer a protective effect on lung parenchyma are fruits, vegetables, fish, nuts, soy, B vitamins, vitamin D, vitamin E, vitamin C, and zinc. Changing dietary habits to decrease the risk of lung cancer can be performed in parallel with smoking cessation programs. There is a need for future studies with large sample sizes to accurately evaluate some aspects of nutrition and their effect on lung cancer risk. Physicians are encouraged to provide nutritional advice to their patients.

Soy and Isoflavone Consumption and Multiple Health Outcomes: Umbrella Review of Systematic Reviews and Meta-Analyses of Observational Studies and Randomized Trials in Humans

SCOPE

To assess the existing evidence of associations between consumption of soy and isoflavone and multiple health outcomes.

METHODS AND RESULTS

This is an umbrella review of meta-analyses and systematic reviews of randomized trials and observational studies in humans. 114 Meta-analyses and systematic reviews are identified with 43 unique outcomes. Soy and isoflavone consumption seems more beneficial than harmful for a series of health outcomes. Beneficial associations are identified for cancers, cardiovascular disease, gynecological, metabolic, musculoskeletal, endocrine, neurological, and renal outcomes, particularly in perimenopausal women. Harmful association is only found for gastric cancer (RR: 1.17, 95% CI: 1.02-1.36) for high intake of miso soup (1-5 cups per day) in male.

CONCLUSION

Generally, soy and isoflavone consumption is more beneficial than harmful. The results herein support promoting soy intake as part of a healthy diet. Randomized controlled trials are necessary to confirm this finding.

Association of Untargeted Urinary Metabolomics and Lung Cancer Risk Among Never-Smoking Women in China

IMPORTANCE

Chinese women have the highest rate of lung cancer among female never-smokers in the world, and the etiology is poorly understood.

OBJECTIVE

To assess the association between metabolomics and lung cancer risk among never-smoking women.

DESIGN, SETTING, AND PARTICIPANTS

This nested case-control study included 275 never-smoking female patients with lung cancer and 289 never-smoking cancer-free control participants from the prospective Shanghai Women's Health Study recruited from December 28, 1996, to May 23, 2000. Validated food frequency questionnaires were used for the collection of dietary information. Metabolomic analysis was conducted from November 13, 2015, to January 6, 2016. Data analysis was conducted from January 6, 2016, to November 29, 2018.

EXPOSURES

Untargeted ultra-high-performance liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance metabolomic profiles were characterized using prediagnosis urine samples. A total of 39 416 metabolites were measured.

MAIN OUTCOMES AND MEASURES

Incident lung cancer.

RESULTS

Among the 564 women, those who developed lung cancer (275 participants; median [interquartile range] age, 61.0 [52-65] years) and those who did not develop lung cancer (289 participants; median [interquartile range] age, 62.0 [53-66] years) at follow-up (median [interquartile range] follow-up, 10.9 [9.0-11.7] years) were similar in terms of their secondhand smoke exposure, history of respiratory diseases, and body mass index. A peak metabolite, identified as 5-methyl-2-furoic acid, was significantly associated with lower lung cancer risk (odds ratio, 0.57 [95% CI, 0.46-0.72]; P < .001; false discovery rate = 0.039). Furthermore, this peak was weakly correlated with self-reported dietary soy intake (ρ = 0.21; P < .001). Increasing tertiles of this metabolite were associated with lower lung cancer risk (in comparison with first tertile, odds ratio for second tertile, 0.52 [95% CI, 0.34-0.80]; and odds ratio for third tertile, 0.46 [95% CI, 0.30-0.70]), and the association was consistent across different histological subtypes and follow-up times. Additionally, metabolic pathway analysis found several systemic biological alterations that were associated with lung cancer risk, including 1-carbon metabolism, nucleotide metabolism, oxidative stress, and inflammation.

CONCLUSIONS AND RELEVANCE

This prospective study of the untargeted urinary metabolome and lung cancer among never-smoking women in China provides support for the hypothesis that soy-based metabolites are associated with lower lung cancer risk in never-smoking women and suggests that biological processes linked to air pollution may be associated with higher lung cancer risk in this population.

Drug Resistance in Non-Small Cell Lung Cancer: A Potential for NOTCH Targeting?

Drug resistance is a major cause for therapeutic failure in non-small cell lung cancer (NSCLC) leading to tumor recurrence and disease progression. Cell intrinsic mechanisms of resistance include changes in the expression of drug transporters, activation of pro-survival, and anti-apoptotic pathways, as well as non-intrinsic influences of the tumor microenvironment. It has become evident that tumors are composed of a heterogeneous population of cells with different genetic, epigenetic, and phenotypic characteristics that result in diverse responses to therapy, and underlies the emergence of resistant clones. This tumor heterogeneity is driven by subpopulations of tumor cells termed cancer stem cells (CSCs) that have tumor-initiating capabilities, are highly self-renewing, and retain the ability for multi-lineage differentiation. CSCs have been identified in NSCLC and have been associated with chemo- and radiotherapy resistance. Stem cell pathways are frequently deregulated in cancer and are implicated in recurrence after treatment. Here, we focus on the NOTCH signaling pathway, which has a role in stem cell maintenance in non-squamous non-small lung cancer, and we critically assess the potential for targeting the NOTCH pathway to overcome resistance to chemotherapeutic and targeted agents using both preclinical and clinical evidence.

Soy and the risk of type 2 diabetes mellitus: A systematic review and meta-analysis of observational studies

BACKGROUND

Increasing studies have focused on the relationship between soy intake and type 2 diabetes mellitus risk, but the results are inconsistent. We conduct a meta-analysis to evaluate the relationship.

METHODS

The databases of PubMed, Web of Science and Embase were searched up to Dec 2016. A random-effect model was used to pool the results of included studies.

RESULTS

Eight studies with 19 reports met the inclusion criteria. A significant inverse association was shown between soy intake and type 2 diabetes mellitus risk with an overall RR of 0.77 (95% CI = 0.66-0.91) with high heterogeneity. Besides, there was an obvious relationship between soy protein and isoflavones intake and risk of T2DM with the summary RR was 0.88 (95% CI = 0.80-0.97) with no heterogeneity. In the subgroup analysis, a statistically significant protective effect of soy consumption was observed in women (RR = 0.65; 95% CI = 0.49-0.87), cross-sectional studies (RR = 0.45; 95% CI = 0.30-0.67), and Asian populations (RR = 0.73; 95% CI = 0.61-0.88).

CONCLUSIONS

Soy products and soy constituents (soy protein and soy isoflavones) may be associated with a lower risk of type 2 diabetes mellitus. Future studies should focus on the dose-response effect and the mechanism.

Secular trend analysis of lung cancer incidence in Sihui city, China between 1987 and 2011

Background

With industrial and econom ic development in recent decades in South China, cancer incidence may have changed due to the changing lifestyle and environment. However, the trends of lung cancer and the roles of smoking and other environmental risk factors in the development of lung cancer in rural areas of South China remain unclear. The purpose of this study was to explore the lung cancer incidence trends and the possible causes of these trends.

Methods

Joinpoint regression analysis and the age–period–cohort (APC) model were used to analyze the lung cancer incidence trends in Sihui, Guangdong province, China between 1987 and 2011, and explore the possible causes of these trends.

Results

A total of 2,397 lung cancer patients were involved in this study. A 3-fold increase in the incidence of lung cancer in both sexes was observed over the 25-year period. Joinpoint regression analysis showed that while the incidence continued to increase steadily in females during the entire period, a sharp acceleration was observed in males starting in 2005. The full APC model was selected to describe age, period, and birth cohort effects on lung cancer incidence trends in Sihui. The age cohorts in both sexes showed a continuously significant increase in the relative risk (RR) of lung cancer, with a peak in the eldest age group (80–84 years). The RR of lung cancer showed a fluctuating curve in both sexes. The birth cohorts identified an increased trend in both males and females; however, males had a plateau in the youngest cohorts who were born during 1955–1969.

Conclusions

Increasing trends of the incidence of lung cancer in Sihui were dominated by the effects of age and birth cohorts. Social aging, smoking, and environmental changes may play important roles in such trends.

Soy food consumption and lung cancer risk: a meta-analysis using a common measure across studies

A published meta-analysis pooled individual studies by using the study-specific odds ratio (OR) or relative risk (RR) for the highest vs. lowest category of soy or isoflavone intake from each study, but it should be problematic to make comparison between studies/populations for lung cancer risk as the quantiles are so different from different studies/populations. Therefore, we conducted a meta-analysis to explore the association between exposure of estimated daily soy protein intake in grams and lung cancer risk. We extracted ORs or RRs and 95% confidence intervals (CIs), converted them to the estimated ones for daily soy protein intake and pooled them using fixed or random effects models from 11 epidemiologic studies. Overall, the inverse association between daily grams of soy protein intake and risk of lung cancer was borderline statistically significant (OR = 0.98, 95% CI = 0.96 to 1.00); the inverse association was statistically significant in nonsmokers (OR = 0.96; 95% CI = 0.93 to 0.99) and stronger than in smokers (P for difference <0.05). No statistical significance for the associations was observed between genders, the origin of the participants, study design and types of soy intake. This study suggests a borderline reduction in risk of lung cancer with daily soy protein intake in grams, and a significant inverse association in nonsmokers.

Habitual consumption of soy products and risk of nasopharyngeal carcinoma in Chinese adults: a case-control study

BACKGROUND AND OBJECTIVES

Many 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.

METHODS

This 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.

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. 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.

CONCLUSION

Habitual consumption of soy products had no significant effect on the risk of nasopharyngeal carcinoma in Chinese adults with a relatively low intake.

Prediagnosis soy food consumption and lung cancer survival in women

PURPOSE

We recently reported an inverse association between soy food intake and lung cancer risk among nonsmoking women. The effect size for aggressive lung cancers was larger than that observed for other types of lung cancer. Therefore, we hypothesized that soy consumption may favorably affect the overall survival of patients with lung cancer.

PATIENTS AND METHODS

This analysis included 444 women with incident lung cancer identified from the Shanghai Women's Health Study. Prediagnosis soy food intake was assessed at enrollment and reassessed 2 years later. Proportional hazards models were used to evaluate the association between soy food intake and overall survival.

RESULTS

Of the 444 patients with lung cancer, 318 died during follow-up. Initial analyses including all patients showed that higher intake of soy food was associated with better overall survival after adjusting for demographic and lifestyle characteristics and other nonclinical factors. Larger effect sizes for the association were found after additional adjustment for tumor stage and treatment in analyses including 301 patients with data available on these clinical factors. Compared with the median intake of soy food, fully adjusted hazard ratios for total mortality associated with the 10th, 30th, 70th, and 90th percentiles of intake were 1.81 (95% CI, 1.26 to 2.59), 1.25 (95% CI, 1.09 to 1.42), 0.88 (95% CI, 0.80 to 0.97), and 0.89 (95% CI, 0.68 to 1.16), respectively. Similar inverse associations were observed for dietary isoflavone intake.

CONCLUSION

This study suggests, to the best of our knowledge for the first time, that, among women with lung cancer, prediagnosis intake of soy food is associated with better overall survival.

Calcium intake and lung cancer risk among female nonsmokers: a report from the Shanghai Women's Health Study

BACKGROUND

Calcium has been implicated in carcinogenesis and linked to the risk of several cancers in epidemiologic studies; however, few studies have investigated the association of calcium intake with lung cancer risk, particularly among nonsmokers.

METHODS

We evaluated the association of intakes of calcium and related minerals, assessed through a food frequency questionnaire, with lung cancer risk among 71,267 female nonsmokers who were cancer free at baseline in the Shanghai Women's Health Study, a population-based, prospective cohort study. Multivariate Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI).

RESULTS

During follow-up through December 2009 (median follow-up time: 11.2 years), 428 incident lung cancer cases accrued. The median intakes of dietary calcium, magnesium, and phosphorus were 441, 266, and 935 mg/d, respectively. Intakes of calcium, phosphorus, and the calcium-to-magnesium (Ca:Mg) ratio were inversely associated with lung cancer risk. The corresponding HRs (95% CIs) for the highest compared with the lowest quartile were 0.66 (0.48, 0.91) for calcium, 0.55 (0.36, 0.85) for phosphorus, and 0.62 (0.47, 0.82) for the Ca:Mg ratio. No association was observed for dietary magnesium intake or the use of calcium- or vitamin D-containing supplements.

CONCLUSIONS AND IMPACT

Our study provides some of the first evidence suggesting a possible role for increasing dietary calcium intake in lung cancer prevention among female nonsmokers, especially in populations with relatively low calcium intake.

Dietary B vitamin and methionine intakes and lung cancer risk among female never smokers in China

PURPOSE

B vitamins and methionine have been postulated to have potential effects on carcinogenesis; however, findings from previous epidemiologic studies on B vitamins, methionine, and lung cancer risk are inconsistent. We investigated associations of dietary intakes of B vitamins (i.e., riboflavin, niacin, vitamin B6, folate, and vitamin B12) and methionine with lung cancer risk among female never smokers.

METHODS

The Shanghai Women's Health Study, a population-based, prospective cohort study, included 74,941 women. During a median follow-up of 11.2 years, 428 incident lung cancer cases accrued among 71,267 women with no history of smoking or cancer at baseline. Baseline dietary intakes were derived from a validated, interviewer-administered food frequency questionnaire. Cancer incidence and vital status were ascertained through annual linkage to the Shanghai Cancer Registry and Shanghai Vital Statistics Registry databases and through biennial in-person follow-ups with participants. Adjusted hazard ratios (HR) and 95 % confidence intervals (CI) were calculated using Cox regression.

RESULTS

Dietary riboflavin intake was inversely associated with lung cancer risk (HR = 0.62; 95 % CI = 0.43-0.89; p trend = 0.03 for the highest quartile compared with the lowest). A higher than median intake of methionine was associated with lower risk of lung cancer (HR = 0.78; 95 % CI = 0.60-0.99); however, there was no dose-response relation. Intakes of other B vitamins were not associated with lung cancer risk.

CONCLUSIONS

Our study suggests that dietary riboflavin intake may be inversely associated with lung cancer risk among female never smokers, which warrants further investigation.