Tofu intake is inversely associated with risk of breast cancer: A meta-analysis of observational studies

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.

Common Misconceptions about Diet and Breast Cancer: An Unclear Issue to Dispel

Breast cancer (BC) constitutes a prevalent health condition among women. Recent years have witnessed the identification of dietary proto-oncogenic factors that deserve attention. Besides the well-known role of alcohol and red and processed meat in BC development, the impact of other dietary components remains unclear. Our narrative review aims to explore the diet-BC relationship, focusing on sugar, dairy, and soy consumption. We conducted a PubMed literature search covering the last decade (2013-2023) and included 35 papers. We found limited evidence on the association between high sugar intake and BC incidence. On the other hand, dairy and soy consumption displayed a protective effect in the majority of the analyzed papers. However, a significant degree of heterogeneity was reported among the results. Menopausal status and the specific BC molecular subtypes were the main factors influencing the interpretation of the results. Exploring dietary factors and BC revealed inconsistencies: high glycemic index post-menopause may be a risk factor, while sugar-sweetened drinks and artificial sweeteners yielded conflicting results; fermented dairy showed potential benefits, non-fermented dairy presented inconsistent findings; soy impact on BC varied according to molecular subtype, with some studies suggesting a positive association in luminal-like BC. Hence, further investigation is crucial to obtain a uniform consensus on the diet-BC relationship.

A Randomized Controlled Trial of Soy Isoflavone Intake on Mammographic Density among Malaysian Women

Soy intake is associated with lower breast cancer risk in observational studies concerning Asian women, however, no randomized controlled trials (RCT) have been conducted among Asian women living in Asia. This three-armed RCT assessed the effects of one-year soy isoflavone (ISF) intervention on mammographic density (MD) change among healthy peri- and postmenopausal Malaysian women. This study was registered at ClinicalTrials.gov (NCT03686098). Participants were randomized into the 100 mg/day ISF Supplement, 50 mg/day ISF Diet, or control arm, and assessed for change in absolute and relative dense area from digital mammograms conducted at enrolment and after 12 months, compared over time across study arms using Kruskal-Wallis tests. Out of 118 women enrolled, 91 women completed the intervention, while 27 women (23%) were lost in follow up. The ISF supplement arm participants observed a larger decline in dense area (−1.3 cm2), compared to the ISF diet (−0.5 cm2) and control arm (−0.8 cm2), though it was not statistically significant (p = 0.48). Notably, among women enrolled within 5 years of menopause; dense area declined by 6 cm2 in the ISF supplement arm, compared to <1.0 cm2 in the control arm (p = 0.13). This RCT demonstrates a possible causal association between soy ISF intake and MD, a biomarker of breast cancer risk, among Asian women around the time of menopause, but these findings require confirmation in a larger trial.

LINC00261/microRNA-550a-3p/SDPR axis affects the biological characteristics of breast cancer stem cells

Long non-coding RNAs (lncRNAs) have been shown to play key roles in the pathogenesis of breast cancer (BC). The study was to explore the effect of long non-coding RNA LINC00261/microRNA (miR)-550a-3p/serum deprivation response (SDPR) axis on the biological characteristics of BC stem cells (BCSCs). BC and adjacent normal tissues of patients were collected. LINC00261, miR-550a-3p and SDPR expression in BC tissues and cell lines and CD24 and CD44 expression in BC tissues was detected. CD44⁺ /CD24^-/low BCSCs were sorted. CD44⁺ /CD24^-/low MDA-MB-231 and MCF-7 cells were screened and transfected with altered expression of LINC00261 or miR-550a-3p to explore their roles in cell viability, microsphere (MS) formation ability, migration and invasion of CD44⁺ /CD24^-/low BCSCs. The targeting relationships of LINC00261, miR-550a-3p and SDPR were detected. Reduced LINC00261, decreased SDPR and elevated miR-550a-3p exhibited in BC tissues of patients and cell lines. Elevated CD44^+/ CD24^- were present in BC tissues. LINC00261 up-regulated SDPR expression as a sponge of miR-550a-3p. Elevated LINC00261 suppressed BC cell viability, MS formation ability, migration and invasion of CD44⁺ /CD24^-/low BCSCs. Moreover, up-regulated miR-550a-3p reversed the inhibitive effect of elevated LINC00261 on BCSCs, and reduced SDPR reversed the promotive effect of decreased miR-550a-3p on BCSCs. The study highlights that LINC00261 can adsorb miR-550a-3p to modulate SDPR, thus inhibiting the viability and MS formation of BC cells, reducing migration and invasion of CD44⁺ /CD24^-/low BCSCs, exerting a potential effect on therapy.

Current Resources for Evidence-Based Practice, September 2020

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of “spin” in scientific reporting and its effect on summaries and syntheses of the literature and commentaries on reviews about early versus late amniotomy as part of labor induction protocols and the economic burden associated with maternal morbidity.

Dietary Fiber and Survival in Women with Breast Cancer: A Dose-Response Meta-Analysis of Prospective Cohort Studies

We aimed to investigate the association of dietary fiber consumption with mortality risk in women with breast cancer. A systematic search was undertaken in PubMed, Scopus, and ISI Web of Science till March 2020 to find cohort studies investigating the association of dietary fiber consumption with mortality risk in women with breast cancer. A random-effects model was used to combine study-specific results. The quality of evidence was rated by NutriGrade score. Seven prospective cohort studies with 1,426 cases of all-cause mortality and 679 cases of breast cancer-specific mortality among 11,295 patients with breast cancer were included. The relative risks for the highest compared to the lowest category of dietary fiber consumption were 0.63 (95%CI: 0.52, 0.77; I² = 0%, n = 5) for all-cause mortality, and 0.72 (95%CI: 0.54, 0.96; I² = 0%, n = 5) for breast cancer-specific mortality. There was a strong linear association between fiber intake and all-cause mortality risk. The quality of evidence was rated moderate for all-cause mortality, and low for breast cancer-specific mortality. Higher dietary fiber consumption may improve survival in patients with breast cancer. More research is needed to confirm the present results, considering types of fiber consumed and tumor estrogen receptor status.