Dietary Inflammatory Index and risk of differentiated thyroid cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial
Exceptionally high incidence rates of differentiated thyroid cancer (DTC) have been reported. The incidence rates were ranging from approximately 1 to 5 per 100,000 men and 2 to 8 per 100,000 women in high-income countries. As around the world, improved sensitivity of tumor detection techniques was likely a major , albeit not the only , contributor to the spike in incidence. At the same time, striking ethnic and geographic disparities in DTC incidence rates can be observed. Lifestyle, genetic and environmental risk factors have been hypothesized. However, studies have yet to fully explain the elevated incidence rates observed. Research on the role of dietary factors in DTC etiology has largely focused on foods that interfere with thyroid function (e.g., foods with high iodine concentration or containing goitrogenic substances). But, so far, these studies have yielded inconsistent results . An area for further exploration of the possible impact of dietary habits on DTC risk is the inflammatory potential of overall diet. Chronic inflammation is known to play an integral part in tumor initiation, progression and malignant conversion. While a direct contribution of inflammation has been established for certain cancer types (e.g., gastric cancer), the relationship between inflammation and DTC appears particularly complex and is still under study. In line with the oft-reported observation of lymphocytic and macrophage infiltration of thyroid tumors, epidemiological evidence to date suggests an association between DTC and systemic inflammatory conditions, such as thyroid autoimmune diseases (e.g., Hashimoto’s thyroiditis) and obesity. Some serum inflammatory biomarkers have also been found linked to DTC (e.g., C-reactive protein, interleukin (IL)-6, IL-7, IL-8, IL-10, IL-13). However, primarily derived from relatively small casecontrol studies, many of these associations have been inconsistently reported. There is growing evidence on the impact of diet on chronic inflammation. Dietary components have been shown to have pro- or anti-inflammatory properties via modulation of inflammatory biomarker levels. Based on such observations, the Dietary Inflammatory Index was developed as a tool for quantifying inflammation derived from an individual’s overall diet. This study is the first attempt to assess dietary inflammation in relation to thyroid carcinoma risk. Its objective was to examine the association between the Dietary Inflammatory Index (DII) and DTC risk in a prospective cohort study. The PLCO is a well characterized and diverse study population with large number of cancer cases that would provide ample power to conduct subgroup analysis.
1) To examine the association between inflammatory potential of diet, as estimated by the DII, and differentiated thyroid cancer (DTC) risk using data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial prospective cohort
2) To evaluate the association of the inflammatory potential of diet and risk of thyroid cancer by the tumor subtypes.
The Department of the Endocrine and Breast Surgery, The First Affiliated hospital of Chongqing Medical university, Chongqing, China;