Dietary inflammatory index and ovarian cancer risk in a large Italian case–control study

Background: While inflammation has been shown to play an important etiologic role in ovarian carcinogenesis, little is known about the association between inflammatory properties of diet and ovarian cancer risk. Methods: We explored the association between the dietary inflammatory index (DII) and ovarian cancer risk in a multicentric Italian case–control study conducted between 1992 and 1999. Cases were 1,031 women with incident, histologically confirmed ovarian cancer from four areas in Italy. Controls were 2,411 women admitted to the same network of hospitals as the cases for acute, non-malignant and non-gynecological conditions, unrelated to hormonal or digestive-tract diseases or committed to long-term modifications of diet. DII scores were computed based on 31 nutrients and food items assessed using a reproducible and validated 78-item food frequency questionnaire. Odds ratios (ORs) were estimated through logistic regression models adjusting for age, total energy intake and other recognized confounding factors. Results: Subjects in the highest quartile of DII scores (i.e., with the most pro-inflammatory diets) had a higher risk of ovarian cancer compared to subjects in the lowest quartile (i.e., with an anti-inflammatory diet) (ORQuartile4vs1 1.47, 95% confidence interval, CI, 1.07, 2.01; ptrend = 0.009). When analyses were carried out using continuous DII, a significant positive association with ovarian cancer was observed: the OR for one-unit increment in DII score (corresponding to approximately 8 % of its range in the current study, +6.0 to −6.20) was 1.08 (95% CI 1.02, 1.14). Conclusion: A pro-inflammatory diet as indicated by higher DII scores is associated with increased ovarian cancer risk.