Plant-based diets have been associated with lower risk of various diseases, including type 2 diabetes, cardiovascular disease, and other cardiometabolic risk factors. However, the association between ...plant-based diet quality and breast cancer remains unclear.
We prospectively followed 76,690 women from the Nurses' Health Study (NHS, 1984-2016) and 93,295 women from the NHSII (1991-2017). Adherence to an overall plant-based diet index (PDI), a healthful PDI (hPDI), and an unhealthful PDI (uPDI) was assessed using previously developed indices. Cox proportional hazards models were used to estimate HR and 95% confidence intervals (CI) for incident invasive breast cancer.
Over 4,841,083 person-years of follow-up, we documented 12,482 incident invasive breast cancer cases. Women with greater adherence to PDI and hPDI were at modestly lower risk of breast cancer (HR
, 0.89; 95% CI, 0.84-0.95); (HR
, 0.89; 95% CI, 0.83-0.94). We observed significant heterogeneity by estrogen receptor (ER) status, with the strongest inverse association between hPDI and breast cancer observed with ER-negative tumors HR
, 0.77; 95% CI, 0.65-0.90;
< 0.01. We also found an inverse association between extreme quintiles of healthy plant foods and ER-negative breast cancer HR, 0.74; 95% CI, 0.61-0.88;
< 0.01.
This study provides evidence that adherence to a healthful plant-based diet may reduce the risk of breast cancer, especially those that are more likely to be aggressive tumors.
This is the first prospective study investigating the relation between healthful and unhealthful plant-based dietary indices and risk of total and subtype-specific breast cancer.
The pregnancy-lactation cycle (PLC) is a period in which the breast is transformed from a less-developed, nonfunctional organ into a mature, milk-producing gland that has evolved to meet the ...nutritional, developmental, and immune protection needs of the newborn. Cessation of lactation initiates a process whereby the breast reverts to a resting state until the next pregnancy. Changes during this period permanently alter the morphology and molecular characteristics of the breast (molecular histology) and produce important, yet poorly understood, effects on breast cancer risk. To provide a state-of-the-science summary of this topic, the National Cancer Institute invited a multidisciplinary group of experts to participate in a workshop in Rockville, Maryland, on March 2, 2012. Topics discussed included: 1) the epidemiology of the PLC in relation to breast cancer risk, 2) breast milk as a biospecimen for molecular epidemiological and translational research, and 3) use of animal models to gain mechanistic insights into the effects of the PLC on breast carcinogenesis. This report summarizes conclusions of the workshop, proposes avenues for future research on the PLC and its relationship with breast cancer risk, and identifies opportunities to translate this knowledge to improve breast cancer outcomes.
•Conventionally grown FVs are the main source of exposure to pesticides.•Overall exposure to pesticides through FV intake is not related to cancer risk.•We cannot dismiss other associations with ...sub-types of specific cancers.•We cannot rule out other relationships with specific chemicals.
Conventionally grown fruits and vegetables (FVs) are the main source of general population exposure to pesticide residues.
To evaluate the relation of intake of high- and low-pesticide-residue FVs with cancer risk.
We followed 150,830 women (Nurses’ Health Study, 1998–2016, and Nurses’ Health Study II, 1999–2017) and 29,486 men (Health Professionals Follow-up Study, 1998–2016) without a history of cancer. We ascertained FV intake via validated food frequency questionnaires and categorized FVs as having high or low pesticide residue levels based on USDA surveillance data. We used Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CI) of total and site-specific cancer related to quintiles of high- and low-pesticide-residue FV intake.
We documented 23,678 incident cancer cases during 2,862,118 person-years of follow-up. In the pooled multivariable analysis, neither high- nor low-pesticide-residue FV intake was associated with cancer. The HRs (95% CI) per 1 serving/day increase in intake were 0.99 (0.97–1.01) for high- and 1.01 (0.99–1.02) for low-pesticide-residue FVs. Additionally, we found no association between high-pesticide-residue FV intake and risk of specific sites, including malignancies previously linked to occupational pesticide exposure (HR, 95% CI comparing extreme quintiles of intake lung 1.17 (0.95–1.43), non-Hodgkin lymphoma 0.89 (0.72–1.09), prostate 1.31 (0.88–1.93)) or inversely related to intake of organic foods (breasts 1.03 (0.94–1.31)).
These findings suggest that overall exposure to pesticides through FV intake is not related to cancer risk, although they do not rule out associations with specific chemicals or sub-types of specific cancers.
Understanding how the timing of exposure to endogenous hormones influences cancer development is critical to elucidating disease etiology. Prolactin increases proliferation and cell motility, ...processes important in later stage tumor development, suggesting that levels proximate (versus distant) to diagnosis may better predict risk. Thus, we calculated relative risks (RR) and 95% confidence intervals (CI) for prolactin levels on samples collected <10 (proximate) versus ≥10 (distant) years before diagnosis in the Nurses' Health Study (NHS) and NHSII with breast cancer risk, including in a subset of NHS women providing two samples 10 years apart. We measured prolactin via immunoassay in cases diagnosed from 1990 to 2010 (NHS) and 1999 to 2009 (NHSII) and matched controls. Overall, 2,468 cases and 4,021 controls had prolactin measured <10 years and 953 cases and 1,339 controls >10 years before diagnosis/reference date. There was an increased risk for higher proximate prolactin levels RR, >15.7 vs. ≤8.1 ng/mL (i.e., top vs. bottom quartiles) = 1.20; 95% CI, 1.03-1.40; Ptrend = 0.005, but not for distant levels (RR = 0.97; Ptrend = 0.94); results were similar among women with two blood samples (Pinteraction, proximate vs. distant = 0.07). The positive association was stronger for ER(+) disease (RR = 1.28; Ptrend = 0.003) and postmenopausal women (RR = 1.37; Ptrend = 0.0002). Among postmenopausal women, the association was strongest for ER(+) disease (RR = 1.52) and lymph node-positive cases (RR = 1.63). Our data suggest that prolactin levels measured <10 years before diagnosis are most strongly associated with postmenopausal breast cancer risk, especially for ER(+) tumors and metastatic disease. This corresponds with biologic data that prolactin is etiologically important in tumor promotion.
We evaluated fiber intake during adolescence and early adulthood in relation to breast cancer (BC) risk in the Nurses' Health Study II.
Among 90,534 premenopausal women who completed a dietary ...questionnaire in 1991, we documented 2833 invasive BC cases during 20 years of follow-up. In 1998, 44,263 of these women also completed a questionnaire about their diet during high school; among these women, we documented 1118 cases of BC by end of follow-up. Multivariable-adjusted Cox proportional hazards regression was used to model relative risks (RRs) and 95% confidence intervals (CIs) for BC across categories of dietary fiber.
Among all women, early adulthood total dietary fiber intake was associated with significantly lower BC risk (RR for highest versus lowest quintile 0.81; 95% CI 0.72-0.91; Ptrend = .002). Higher intakes of soluble fiber (RR for highest versus lowest quintile 0.86; 95% CI 0.77-0.97; Ptrend = .02) and insoluble fiber (RR for highest versus lowest quintile 0.80; 95% CI 0.71-0.90; Ptrend < .001) were each associated with lower BC risk. Total dietary fiber intake in adolescence was also associated with lower BC risk (RR for highest versus lowest quintile 0.84; 95% CI 0.70-1.01; Ptrend = .04). For the average of fiber intake during adolescence and early adult life, the RR comparing highest with lowest quintiles was 0.75 (95% CI 0.62-0.91, Ptrend = .004).
Our findings support the hypothesis that higher fiber intakes reduce BC risk and suggest that intake during adolescence and early adulthood may be particularly important.
Hyperinsulinemia and higher insulin-like growth factors may increase breast cancer risk. We evaluated a diabetes risk reduction diet (DRRD) and breast cancer risk.
We prospectively evaluated the ...association between adherence to a DRRD and the incidence of breast cancer.
We followed 88,739 women from the Nurses’ Health Study (NHS; 1980–2016) and 93,915 women from the NHSII (1991–2017). Incident breast cancer cases (n = 11,943) were confirmed with medical records, and subtypes were determined by tissue microarray data and pathology reports. Information on diet and breast cancer risk factors was repeatedly ascertained in follow-up questionnaires. A DRRD score was derived with 9 factors: lower glycemic index of diet; lower intakes of trans fat, sugar-sweetened beverages/fruit juices, and red/processed meat; higher intakes of cereal fiber, coffee, nuts, and whole fruits; and a higher ratio of polyunsaturated to saturated fat (score range: 9–45). Multivariable-adjusted hazard ratios (MVHRs) and 95% CIs were calculated with Cox proportional hazards models.
Being in the highest compared with the lowest DRRD adherence quintile was associated with a modestly lower breast cancer risk (MVHRQ5vsQ1: 0.89; 95% CI: 0.84, 0.95; P-trend = 0.0002); this was attenuated after adjusting for weight change since age 18 y (MVHRQ5vsQ1: 0.92; 95% CI: 0.87, 0.98; P-trend = 0.01). The inverse association was strongest among women with current BMI < 25 kg/m2 (MVHRQ5vsQ1: 0.89; 95% CI: 0.81, 0.98; P-trend = 0.004; P-interaction = 0.04). Among tumor molecular subtypes, the strongest inverse association was observed with basal-type tumors (MVHRQ5vsQ1: 0.67; 95% CI: 0.45, 1.01; P-trend = 0.04).
Greater DRRD-adherence was associated with lower breast cancer risk, likely mediated by less weight gain with a DRRD; however, independently of weight change, DRRD-adherence was modestly associated with lower breast cancer risk, particularly among lean women.
Although several dietary patterns have been associated with incident colorectal cancer (CRC), it is unclear which diet is optimal.
Participants included 48 409 men and 169 772 women from three ...USA-based prospective cohort studies. We compared the associations of 18 dietary patterns with CRC risk, including two reference scores. The reference scores were derived based on the dietary recommendations for cancer prevention and CRC-specific dietary risk factors mentioned in the 2018 World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR) Third Expert Report. Multivariable Cox proportional hazards models were fitted to estimate hazard ratios (HRs) and 95% CIs.
Most dietary patterns showed moderate correlations with the WCRF dietary score (absolute values of Spearman correlation coefficients: 0.45-0.63), except the Plant-based diet index, low-carbohydrate diets, the Empirical dietary index for hyperinsulinemia (EDIH) and Empirical dietary inflammation pattern (EDIP). HR for the 10th-90th percentile difference in the score was 0.86 (95% CI: 0.78-0.94) for the Dietary Approaches to Stop Hypertension score (DASH), 1.15 (1.06-1.26) for Western dietary pattern, 1.20 (1.10-1.31) for EDIH and 1.23 (1.13-1.34) for EDIP. These associations between patterns and CRC risk persisted after adjusting for the two reference scores.
Although further research is needed to improve the WCRF/AICR dietary recommendations, our comprehensive assessment of dietary patterns revealed that the DASH, Western dietary pattern, EDIH and EDIP may be the most relevant diets for preventing CRC.
We evaluated the relation of fruit and vegetable consumption, including specific fruits and vegetables, with incident breast cancer characterized by menopausal status, hormone receptor status and ...molecular subtypes. Fruit and vegetable consumption, cumulatively averaged across repeated, validated questionnaires, was examined in relation to risk of invasive breast cancer among 182,145 women initially aged 27–59 years in the Nurses’ Health Study (NHS, 1980–2012) and NHSII (1991–2013). Cox proportional hazards regression, adjusted for known risk factors, was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) and assessed tumors by hormone receptor status and molecular subtypes. We prospectively documented 10,911 invasive breast cancer cases. Greater intake of total fruits and vegetables, especially cruciferous and yellow/orange vegetables, was associated with significantly lower breast cancer risk (>5.5 vs. ≤2.5 servings/day HR = 0.89, 95% CI = 0.83–0.96; ptrend = 0.006). Intake of total vegetables was especially associated with lower risk of estrogen receptor negative tumors (HR per 2 additional servings/day as a continuous variable = 0.84, 95%CI = 0.77–0.93; pheterogeneity = 0.02). Among molecular subtypes, higher intake of total fruits and vegetables (HR per 2 additional servings/day as a continuous variable) was most strongly associated with lower risk of human epidermal growth factor receptor 2 (HER2)‐enriched (HR = 0.79, 95%CI = 0.67–0.93), basal‐like (HR = 0.84, 95%CI = 0.72–0.97) and luminal A (HR = 0.94, 95%CI = 0.89–0.99), but not with luminal B tumors (pheterogeneity = 0.03). In conclusion, our findings support that higher intake of fruits and vegetables, and specifically cruciferous and yellow/orange vegetables, may reduce the risk of breast cancer, especially those that are more likely to be aggressive tumors.
What's new?
Fruits and vegetables are rich in potentially anti‐carcinogenic nutrients including fiber, vitamins C and E, carotenoids, and other bioactive substances. However, many studies found no association between fruit and vegetable consumption and risk of breast cancer. In this analysis based on two large prospective cohorts, the authors found that higher total fruit and vegetable consumption during adulthood was associated with a modest, statistically significant lower invasive breast cancer incidence, with the strongest associations for ER‐negative, HER2‐enriched and basal‐like tumors. Higher intake of fruits and vegetables, and specifically cruciferous and yellow/orange vegetables, may reduce the risk of breast cancer, especially aggressive tumors.
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