Prospective study of the dietary inflammatory index and risk of breast cancer in postmenopausal women

Meta-analysis of the association between dietary inflammatory index (DII) and cancer outcomes

Proinflammatory dietary patterns have been associated with increased cancer risk and mortality. We present a systematic review and meta-analysis of the current published literature on a dietary inflammatory index (DII) score and its association with cancer risk and mortality outcomes. Published articles from online databases (PubMed, Scopus, and Embase) examining the association between DII and any cancer risk, incidence, or mortality between 1980 and November 2016 were selected for review. Results of studies meeting inclusion criteria were summarized and meta-analyzed using STATA to generate summary measures of association across studies. Sixty-three published articles were identified from the search, and following title, abstract and full-text review, twenty-four studies met inclusion criteria. All articles calculated DII scores based on study-specific food-frequency questionnaires using methodology from the same article. Of the 24 included studies, 13 were case-control, 6 were prospective cohort, 1 was a retrospective cohort, 3 were RCTs, and 1 did not specify study design. The most common cancers examined were colorectal, breast, lung, and prostate. Individuals in the highest versus lowest DII categories had 25% increased risk of overall cancer incidence (RR: 1.25, 95% CI: 1.16-1.35), 75% higher odds of cancer (OR: 1.75, 95% CI: 1.43-2.16) and 67% increased risk of cancer mortality (RR: 1.67, 95% CI: 1.13-2.48). Upon stratification for cancer type, positive associations remained (RR_breast : RR: 1.12, 95% CI: 1.03-1.22) (RR_colorectal : 1.33, 95% CI: 1.22-1.46) (RR_lung : 1.30, 95% CI: 1.13-1.50). There were consistent and significant positive associations between higher DII and cancer incidence and mortality across cancer types, study populations, and study design.

Dietary inflammatory index and risk of renal cancer in the Iowa Women's Health Study

BACKGROUND

The association between inflammatory potential of diet and renal cancer risk has not been investigated.

METHODS

In this study, we explored the association between the dietary inflammatory index (DII) and risk of renal cancer in the Iowa Women's Health Study. From 1986 to 2011, 33,817 women initially recruited at 55-69 years of age were followed for incident renal cancers (n = 263). The DII was computed based on dietary intake assessed using a reproducible and valid 121-item food frequency questionnaire. Cox proportional hazards regression was used to estimate hazard ratios (HR) adjusting for age, body mass index, energy intake, smoking status, education, pack years of smoking, hypertension, and hormone replacement therapy.

RESULTS

Multivariable analyses revealed positive association between higher DII scores and renal cancer risk (HR for DII_continuous: 1.07 per unit increase in DII (corresponding to 10% change in the DII range in the current study); 95% CI 1.00, 1.15; HR for DII_tertile3vs1 = 1.52; 95% CI 1.09, 2.13). Stratified analyses produced slightly stronger associations between DII and renal cancer risk among women with BMI <30 kg/m² (HR_Tertile3vs1 = 1.57; 95% CI = 1.04, 2.36) and ever smokers (HR_tertile3vs1 = 2.35; 95% CI = 1.22, 4.55), although the corresponding interaction p values were not significant.

CONCLUSION

Pro-inflammatory diet, as indicated by higher DII scores, was associated with increased renal cancer risk.