The effects of soy consumption before diagnosis on breast cancer survival: the Multiethnic Cohort Study

Phytonutrients and outcomes following breast cancer: a systematic review and meta-analysis of observational studies

BACKGROUND

Phytonutrient intakes may improve outcomes following breast cancer, but the impact of postdiagnosis introduction vs established prediagnostic exposure as well as optimum doses has not been established. Evidence from observational studies for key exposures was evaluated, including dosage and intake time frames.

METHODS

MEDLINE, EMBASE, CINAHL, Cochrane Library, ClinicalTrials.gov, and the ISRCTN registry were searched for prospective and retrospective observational studies investigating the impact of soybean, lignans, cruciferous (cabbage-family) vegetables, green tea, or their phytonutrients on breast cancer survival outcomes. A random-effects model was used to calculate summary hazard ratios (HRs) and 95% confidence intervals (CIs). Nonlinear dose-response analyses were conducted using restricted cubic splines.

RESULTS

Thirty-two articles were included. Soy isoflavones were associated with a 26% reduced risk of recurrence (HR = 0.74, 95% CI = 0.60 to 0.92), particularly among postmenopausal (HR = 0.72, 95% CI = 0.55 to 0.94) and estrogen receptor-positive survivors (HR = 0.82, 95% CI = 0.70 to 0.97), with the greatest risk reduction at 60 mg/day. In mortality outcomes, the reduction was mostly at 20 to 40 mg/day. Soy protein and products were inversely associated with cancer-specific mortality for estrogen receptor-positive disease (HR = 0.75, 95% CI = 0.60 to 0.92). An inverse association was observed for serum or plasma enterolactone, measured prediagnosis and early postdiagnosis, with cancer-specific mortality (HR = 0.72, 95% CI = 0.58 to 0.90) and all-cause mortality (HR = 0.69, 95% CI = 0.57 to 0.83). No effects were observed for cruciferous vegetables. There was a 44% reduced risk of recurrence with prediagnostic green tea for stage I and II breast cancer (HR = 0.56, 95% CI = 0.38 to 0.83).

CONCLUSIONS

Soy, enterolactone, and green tea demonstrated significant risk reductions in outcomes following breast cancer. Evidence is needed regarding the impact of postdiagnostic introduction or substantial increase of these exposures.

Dietary Isoflavone Intake and Breast Cancer Prognosis: A Prospective Analysis and Meta-Analysis

We aimed to examine the association between dietary isoflavone intake and the risk of breast cancer recurrence and summarize evidence on the role of dietary isoflavone intake in breast cancer prognosis. This prospective study included 592 breast cancer survivors who completed a dietary assessment. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. Of the studies published until May 31, 2023, that were searched in PUBMED and EMBASE databases, 14 studies were selected. Adjusted HRs were combined using fixed- or random-effects models. During the median follow-up of 4.3 years, 47 recurrences were identified. The HR (95% CI) for recurrence comparing the highest versus the lowest tertile of isoflavones intake was 1.29 (0.60-2.78). In a meta-analysis of previously published data and ours, dietary isoflavone intake was associated with a better breast cancer prognosis. The combined HRs (95% CIs) comparing the extreme categories were 0.81 (0.67-0.98) for recurrence and 0.85 (0.76-0.96) for all-cause mortality. A nonlinear inverse association was observed between isoflavone intake and the risk of recurrence and all-cause mortality. Our study suggests that dietary isoflavone intake is associated with a favorable prognosis in breast cancer survivors and warrants further investigation.

Gender-specific effects of soybean consumption on cardiovascular events in elderly individuals from rural Northeast China - a prospective cohort study

BACKGROUND

The impact of consuming soybean and its products on cardiovascular events (CVEs), cardiovascular mortality, and all-cause mortality remains unclear. This study aimed to examine the prospective association of soybean consumption with CVEs, cardiovascular mortality, and all-cause mortality among the elderly population in rural China.

METHODS

The Northeast China Rural Cardiovascular Health Study included 2477 elderly individuals (mean age 67 ± 6 years, 49.97% men) in the initial phase of the study from 2012 to 2013, with a follow-up period between 2015 and 2017. Soybean consumption was categorized as follows: low-frequency consumption: rare consumption; moderate-frequency consumption: two to three times/week; high-frequency consumption: ≥ four times/week. Cox proportional hazard analysis assessed the potential relationship of soybean consumption with CVEs, cardiovascular mortality, and all-cause mortality.

RESULTS

The prevalence of soybean and its product consumption was as follows: 38.3% for low-frequency consumption (43.8% for women; 32.8% for men), 49.7% for moderate-frequency consumption (45.8% for women; 53.7% for men), and 11.9% for high-frequency consumption (10.4% for women; 13.5% for men). After adjusting for possible confounders, Cox proportional hazard analysis revealed that the frequency of soybean consumption was an effective predictor of CVEs [Hazard ratio (HR) high (95% CI): 0.555 (0.348, 0.883)], stroke [HR moderate (95% CI): 0.672 (0.494, 0.913); HR high (95% CI): 0.483 (0.276, 0.842)], and all-cause mortality [HR high (95% CI): 0.540 (0.310, 0.942)] in the overall older population. High-frequency consumption of soybean [HR (95% CI): 0.467 (0.225, 0.968)] and moderate-frequency consumption [HR (95% CI): 0.458 (0.270, 0.779)] were associated with stroke events in older men and women, respectively. In addition, high-frequency consumption of soybean [HR (95% CI): 0.437 (0.197, 0.968)] decreased the risk of CVEs in older women.

CONCLUSION

Soybean consumption is closely associated with CVEs and all-cause mortality in older individuals residing in rural areas, with a significant gender discrepancy in this relationship. These findings provide new insights into the impact of soybean consumption on cardiovascular well-being in the elderly rural population, thus enhancing our understanding of this field of interest.

Phytoestrogens and Breast Cancer: Should French Recommendations Evolve?

Breast cancer (BC) occurs less frequently in Asia, where there is high soy consumption. It has been hypothesized that soy isoflavones could be protective against BC recurrence and mortality. At the same time, health organizations in several countries have differing recommendations for soy consumption (soy foods or dietary supplements) in BC survivors. The objective of this review is to analyze the literature and to determine whether it is justified to advise avoiding soy in dietary supplements and/or food in women with a history of BC. We conducted a systematic literature search with the Medline/Pubmed and Web of Science databases. Only prospective cohort studies published since 2009 were retained. The endpoint of studies was BC recurrence and/or mortality, and the association with soy isoflavone intake was specifically targeted. Seven studies were included. None of these studies found statistically significant adverse effects of soy consumption on BC recurrence or mortality (specific or all-cause). Overall, only one study was not able to find beneficial effects of soy intake on BC patients. The other studies concluded that there were positive associations but in very variable ways. Two studies found a decrease in BC recurrence associated with a higher isoflavone intake only for post-menopausal women. The other four studies concluded that there were positive associations regardless of menopausal status. Four studies showed better results on women with hormonal-sensitive cancer and/or patients receiving hormonal treatment. Only one found a stronger association for patients with ER-negative BC. No adverse effects of soy isoflavones on BC mortality/recurrence were found. Soy isoflavones may exert beneficial effects. These results coincide with other recent works and suggest that soy isoflavone intake is safe for BC survivors. Thus, these data no longer seem to coincide with the French recommendations, which could then be brought to evolve. However, in order to confirm the current results, larger studies are needed.

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.

Intake of isoflavones reduces the risk of all-cause mortality in middle-aged Japanese

BACKGROUND/OBJECTIVES

To clarify the effects of intake of legumes and isoflavones on all-cause mortality in middle-aged and older Japanese.

SUBJECT/METHODS

The subjects were 2136 randomly chosen community-dwelling Japanese men and women aged 40-79 years who participated in a first-wave survey (1997-2000; baseline). The subjects were followed from baseline to December 31, 2017 (mean period of 16.6 ± 4.2 years). Intake of legumes, soybeans, and isoflavones at baseline was assessed using a 3-day dietary record with photographs. The relationships of intake amounts of legumes and isoflavones to mortality were assessed using Cox proportional hazards regression controlling for age, sex, education, employment, body mass index, smoking habits, medical histories, drinking, and energy intake.

RESULTS

There were 491 deaths during the follow-up period. We found inverse associations of the intake of total soy products and intake of each of the isoflavones with all-cause mortality (p for trend < 0.05) in subjects aged < 60 years: the multivariate-adjusted hazard ratios (95% confidence intervals) for all-cause mortality in the highest intake group (third tertile) of total soy products and total isoflavones were 0.32 (0.13-0.78) and 0.35 (0.17-0.73), respectively, compared with the reference group (first tertile). In contrast, there were no significant associations of intake amounts of legumes, soybeans, and isoflavones with all-cause mortality in subjects aged 60 years or older.

CONCLUSIONS

The findings suggest that a higher intake of isoflavones might decrease the risk of all-cause mortality, especially in middle-aged Japanese.

Dietary Factors and Breast Cancer Prognosis among Breast Cancer Survivors: A Systematic Review and Meta-Analysis of Cohort Studies

Simple Summary

While most systematic reviews have focused on the association between dietary factors and breast cancer incidence, this current study focuses on the association between comprehensive dietary factors and breast cancer prognosis among breast cancer survivors by systematic review and meta-analysis. We reviewed a total of 63 cohort studies to assess the association between dietary factors and breast cancer prognosis by subgroup analysis with prediagnostic or postdiagnostic dietary intake, menopausal status, and dietary or supplementary micronutrient intake. We found that unhealthy dietary patterns, including the intake of beer and saturated fat, exacerbated the risk of breast cancer prognosis; however, the supplementation of most vitamins was desirable for breast cancer prognosis. Therefore, this study’s systematic review and meta-analysis provide useful dietary information for the development of dietary guidelines/recommendations to improve prognosis among breast cancer survivors.

Abstract

Few studies have summarized the association between dietary factors and breast cancer (BC) prognosis among breast cancer survivors (BCS). Therefore, we carried out a systematic review and meta-analysis to determine the associations between dietary factors and BC prognosis among BCS. We performed a literature search in PubMed and Embase to investigate the association between dietary factors and BC prognosis. We applied a random-effects model to compute the hazard ratio/relative risk and their 95% confidence intervals and heterogeneity (Higgins I²) and to generate forest plots using STATA. Among the 2279 papers identified, 63 cohort studies were included in the systematic review and meta-analysis. Our main finding was that higher consumption of beer and saturated fat negatively affected BC prognosis. However, the intake of lignans, fiber, multivitamins, and antioxidants was negatively associated with the risk of mortality. Furthermore, we performed subgroup analyses by menopausal status and dietary or supplementary micronutrient intake. Most trends were similar to the main findings; in particular, the vitamin C, vitamin D, and vitamin E supplements decreased the risk of mortality. This study’s current systematic review and meta-analysis provide comprehensive dietary information for the development of dietary guidelines/recommendations to improve prognosis among BCS.

Dietary phytoestrogens and biomarkers of their intake in relation to cancer survival and recurrence: a comprehensive systematic review with meta-analysis

CONTEXT

Recent studies have outlined the potential role of dietary factors in patients who have survived cancer.

OBJECTIVE

The aim of this study was to summarize the evidence of the relation between dietary intake of phytoestrogens and their blood biomarkers and, overall, cancer-specific mortality and recurrence in patients with cancer.

DATA SOURCES

A systematic search of PubMed, EMBASE, and Web of Science databases of studies published up to September 2019 was performed. Databases were searched for prospective and retrospective cohort studies reporting on dietary phytoestrogen intake and/or blood biomarkers and the outcomes investigated.

DATA EXTRACTION

Data were extracted from each identified study using a standardized form.

DATA ANALYSIS

Twenty-eight articles on breast, lung, prostate, and colorectal cancer, and glioma were included for systematic review. Given the availability of studies, a quantitative meta-analysis was performed solely for breast cancer outcomes. A significant inverse association among higher dietary isoflavone intake, higher serum/plasma enterolactone concentrations, and overall mortality and cancer recurrence was found. Among other cancer types, 2 studies reported that higher serum enterolactone and higher intake of lignans were associated with cancer-specific survival for colorectal cancer and glioma, respectively.

CONCLUSIONS

Dietary phytoestrogens may play a role in survival from breast cancer ; evidence regarding other cancers is too limited to draw any conclusions.

Pre-diagnosis and early post-diagnosis dietary soy isoflavone intake and survival outcomes: A prospective cohort study of early stage breast cancer survivors

BACKGROUND

There is concern that the estrogen-like effects of soy isoflavones may stimulate mammary tumor growth and interfere with the efficacy of breast cancer treatment. This study aimed to examine prospectively the associations of dietary soy isoflavone intake with all-cause mortality and breast cancer (BC) specific mortality and recurrence among BC survivors.

DESIGN

The study included 1460 Chinese women with early-stage incident BC. Pre-diagnosis and early post-diagnosis soy food intakes were assessed at study entry, and at 18-month follow-up using validated soy food frequency questionnaire. Associations of soy isoflavone intake with prognostic outcomes within 48 months were examined using multivariable adjusted Cox proportional hazards models.

RESULTS

We observed increasing pre-diagnosis and early post-diagnosis soy isoflavone intakes up to the third quartile (Q3) were associated with reductions for adverse prognostic outcomes. Relative to the lowest quartile (Q1), the hazard ratios (HRs) for all-cause mortality for pre-diagnosis and post-diagnosis Q3 intake were respectively 0.34 (95% CI, 0.16-0.74), and 0.44 (95% CI, 0.22-0.89). A similar risk reduction was observed for pre- and post-diagnosis intakes and BC-specific mortality when comparing Q3 versus Q1 with the respective HRs 0.36 (95% CI, 0.16-0.82), and 0.49 (95% CI, 0.23-1.01). Subgroup analyses showed more favourable prognostic outcomes in association with moderate soy intake among premenopausal women, those with triple negative cancer and recipients of tamoxifen treatment.

CONCLUSION

Moderate soy isoflavone intake was associated with favourable prognostic outcomes in Chinese early stage BC survivors.

Effect of isoflavones on breast cancer cell development and their impact on breast cancer treatments

PURPOSE

Epidemiological studies have suggested that intake of soy isoflavones is associated with a reduced risk of development of breast cancer and an improved prognosis in patients with breast cancer. In addition, basic research has demonstrated the antitumor effects of these compounds on breast cancer cell lines. However, the detailed effects of the intake of equol, which is one of the metabolites of the soy isoflavones, are yet to be clarified on the risk of development and recurrence of breast cancer and its interactions with drugs used for treating breast cancer. This study aimed to determine the antitumor effects of equol and investigate the impact of adding equol to therapeutic agents for breast cancer using breast cancer cell lines.

METHODS

We examined the antitumor effect of equol on breast cancer cell lines using MTS assay. We also studied the combined effect of equol and the existing hormonal or chemotherapeutic agents using combination index. We evaluated the expressions of the related proteins by Western blot analysis and correlated the findings with the antitumor effect.

RESULTS

Equol showed bi-phasic protumor and antitumor effects; at a low concentration, it promoted the tumor growth in hormone receptor-positive cell lines, whereas antitumor effects were generally observed when an excessive amount of dose unexpected in the blood and the tissue was administered. When used with tamoxifen, equol might have some antagonistic effect, although it depends on equol concentration and the type of cancer cells.

CONCLUSIONS

We confirmed that equol has dual action, specifically a tumor growth-promoting effect and an antitumor effect. Although the results suggested that equol might exert an antagonistic effect against tamoxifen depending on the concentration, equol did not exert an antagonistic effect on other therapeutic agents.

Legume and Nuts Consumption in Relation to Odds of Breast Cancer: A Case-Control Study

Previous studies on the association between legume and nuts intake and risk of breast cancer have mainly been focused on individual components of legume or nuts, rather than consumption of the whole food group. This study aimed to investigate the relation between legume and nuts intake in relation to breast cancer in Iranian women. In this population-based case-control study, we enrolled 350 pathologically confirmed new cases of breast cancer and 700 controls which were matched with cases in terms of age and socioeconomic status. Dietary intakes were assessed using a validated block-format 168-item semi-quantitative food frequency questionnaire. Legume intake was computed by summing up the consumption of lentils, peas, chickpeas, and different kinds of beans, including red beans and pinto beans. To calculate nuts consumption, we summed up intake of mixed nuts, almond, peanut, walnut and hazelnut. Data on potential confounding variables were also collected using pre-tested questionnaires. Mean consumption of legume and nuts among cases and controls were 14.7 ± 15.0 and 2.3 ± 5.6, respectively. A significant inverse association was found between legume intake and breast cancer (OR: 0.41, 95% CI: 0.30-0.57); such that after adjusting for confounders, participants in the top tertile of legume intake had 46% lower odds of breast cancer compared with those in the bottom tertile (OR: 0.54, 95% CI: 0.36-0.88). Such inverse association was seen among postmenopausal women (OR: 0.51, 95% CI: 0.31-0.85) and also among normal-weight participants (OR: 0.49, 95% CI: 0.29-0.82). In terms of nuts intake, it was inversely associated with odds of breast cancer (OR: 0.16, 95% CI: 0.11-0.23). This association remained significant even after taking potential confounders into account (OR: 0.15, 95% CI: 0.09-0.26). The same association was also seen in premenopausal women (OR: 0.21, 95% CI: 0.14-0.31), postmenopausal women (OR: 0.23, 95% CI: 0.13-0.42), normal-weight (OR: 0.15, 95% CI: 0.08-0.28), and overweight or obese people (OR: 0.27, 95% CI: 0.10-0.71). Our findings on the inverse association of legume and nuts intake with odds of breast cancer support the current recommendations on these foods. Prospective studies are needed to further examine this link.

Soy, Soy Isoflavones, and Protein Intake in Relation to Mortality from All Causes, Cancers, and Cardiovascular Diseases: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

OBJECTIVE

We conducted a systematic review and dose-response meta-analysis of prospective studies to summarize findings on the associations between intakes of soy, soy isoflavones, and soy protein and risk of mortality from all causes, cancers, and cardiovascular diseases.

METHODS

Online databases were systematically searched to identify relevant articles published earlier than May 2018. We applied restricted cubic splines using random-effects analysis to assess dose-response associations. Between-study heterogeneity was assessed by I2 value and Cochrane Q test. Potential publication bias was assessed by visual inspection of funnel plots and Begg regression test.

RESULTS

In total, 23 prospective studies with an overall sample size of 330,826 participants were included in the current systematic review and the meta-analysis. Soy/soy products consumption was inversely associated with deaths from cancers (pooled relative risk 0.88, 95% CI 0.79 to 0.99; P=0.03; I2=47.1%, 95% CI 0.0% to 75.4%) and cardiovascular diseases (pooled effect size: 0.85, 95% CI 0.72 to 0.99; P=0.04; I2=50.0%, 95% CI 0.0% to 77.6%). Such significant associations were also observed for all-cause mortality in some subgroups of the included studies, particularly those with higher quality. In addition, higher intake of soy was associated with decreased risk of mortality from gastric, colorectal, and lung cancers as well as ischemic cardiovascular diseases. Participants in the highest category of dietary soy isoflavones intake had a 10% lower risk of all-cause mortality compared with those in the lowest category. We also found that a 10-mg/day increase in intake of soy isoflavones was associated with 7% and 9% decreased risk of mortality from all cancers and also breast cancer respectively. Furthermore, a 12% reduction in breast cancer death was indicated for each 5-g/day increase in consumption of soy protein. However, intake of soy protein was not significantly associated with all-cause and cardiovascular diseases mortality.

CONCLUSIONS

Soy and its isoflavones may favorably influence risk of mortality. In addition, soy protein intake was associated with a decreased risk in the mortality of breast cancer. Our findings may support the current recommendations to increase intake of soy for greater longevity.

Dietary Natural Products for Prevention and Treatment of Breast Cancer

Breast cancer is the most common cancer among females worldwide. Several epidemiological studies suggested the inverse correlation between the intake of vegetables and fruits and the incidence of breast cancer. Substantial experimental studies indicated that many dietary natural products could affect the development and progression of breast cancer, such as soy, pomegranate, mangosteen, citrus fruits, apple, grape, mango, cruciferous vegetables, ginger, garlic, black cumin, edible macro-fungi, and cereals. Their anti-breast cancer effects involve various mechanisms of action, such as downregulating ER-α expression and activity, inhibiting proliferation, migration, metastasis and angiogenesis of breast tumor cells, inducing apoptosis and cell cycle arrest, and sensitizing breast tumor cells to radiotherapy and chemotherapy. This review summarizes the potential role of dietary natural products and their major bioactive components in prevention and treatment of breast cancer, and special attention was paid to the mechanisms of action.

Dietary isoflavone intake and all-cause mortality in breast cancer survivors: The Breast Cancer Family Registry

BACKGROUND

Soy foods possess both antiestrogenic and estrogen-like properties. It remains controversial whether women diagnosed with breast cancer should be advised to eat more or less soy foods, especially for those who receive hormone therapies as part of cancer treatment.

METHODS

The association of dietary intake of isoflavone, the major phytoestrogen in soy, with all-cause mortality was examined in 6235 women with breast cancer enrolled in the Breast Cancer Family Registry. Dietary intake was assessed using a Food Frequency Questionnaire developed for the Hawaii-Los Angeles Multiethnic Cohort among 5178 women who reported prediagnosis diet and 1664 women who reported postdiagnosis diet. Cox proportional-hazard models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

During a median follow-up of 113 months (approximately 9.4 years), 1224 deaths were documented. A 21% decrease was observed in all-cause mortality for women who had the highest versus lowest quartile of dietary isoflavone intake (≥1.5 vs < 0.3 mg daily: HR, 0.79; 95% confidence interval CI, 0.64-0.97; P_trend  = .01). Lower mortality associated with higher intake was limited to women who had tumors that were negative for hormone receptors (HR, 0.49; 95% CI, 0.29-0.83; P_trend  = .005) and those who did not receive hormone therapy for their breast cancer (HR, 0.68; 95% CI, 0.51-0.91; P_trend  = .02). Interactions, however, did not reach statistical significance.

CONCLUSIONS

In this large, ethnically diverse cohort of women with breast cancer living in North America, a higher dietary intake of isoflavone was associated with reduced all-cause mortality. Cancer 2017;123:2070-2079. © 2017 American Cancer Society.

Impact of Elimination or Reduction of Dietary Animal Proteins on Cancer Progression and Survival: Protocol of an Online Pilot Cohort Study

Background

Current evidence suggests that the incidence of cancer is low in vegan populations, and experimental studies have revealed a significant role of dietary proteins in cancer development and progression. However, little data currently exists regarding the effect of a plant-based diet on the progression of diagnosed cancer.

Objective

The main objective of this study is to determine if a reduction or total elimination of animal protein from the diet can positively influence the outcome of an existing cancer and, in addition to standard oncological therapies, increase remission rates.

Methods

The primary aim of this online study is to test the effect on remission rates in cancer patients (primary outcome) with distinct self-selected dietary patterns (omnivore, lacto-ovo-vegetarian, vegan), and allow for an estimation of the effect size. Secondary outcomes are tumor behavior, relapse-free interval, therapies, therapy tolerability and side-effects, comorbidities, medication, quality of life, acceptance, and feasibility of the selected diet. Safety concerns exist for vegan diets (especially in cancer patients) and the study will carefully monitor for deterioration of health, tumor progression, or malnutrition. Furthermore, the study will evaluate the online portal as a study platform (technical and safety aspects, and sequence of displayed questionnaires) as well as the validity of self-reported and online-generated data.

Results

The study was performed between April, 2015 and June, 2016, and a preliminary evaluation of safety aspects was undertaken after June, 2016. Primary and secondary outcomes will be evaluated when the final patients complete the study in December, 2016.

Conclusions

This study will reveal information about the effects of dietary patterns on cancer disease and progression. The methodology of the study addresses several aspects and limitations of nutrition studies in cancer patients, such as precision of nutrition data, acceptance criteria, online methodology, and safety aspects.

ClinicalTrial

Clinicaltrials.gov NCT02437474; https://clinicaltrials.gov/ct2/show/NCT02437474 (Archived by WebCite at http://www.webcitation.org/6jL7UUCVq)