Self-Reported Eating-Occasion Frequency and Timing are Reproducible and Relatively Valid in the American Cancer Society Cancer Prevention Study-3 Diet Assessment Substudy

BACKGROUND

Accurate assessment of eating-occasion behaviors, such as timing, frequency, and consumption intervals, is important for evaluating associations with obesity and other chronic diseases.

OBJECTIVES

The main objective of this study was to assess the relative validity of a 24-hour grid approach to assess eating-occasion timing and frequency in comparison to data derived from repeated 24-hour dietary recalls (DRs). A second objective was to assess the 1-year test-retest reproducibility of the 24-hour grid.

METHODS

Between 2015 and 2016, 626 participants in the Cancer Prevention Study-3 (CPS-3) Diet Assessment Substudy (mean age, 52 years; age range, 31-70 years; 64% female; 64% non-Hispanic white, 22% non-Hispanic black, 14% Hispanic) completed 2 grids and up to 6 unannounced, telephone, interviewer-administered DRs over 1 year. Spearman correlations (ρ; 95% CIs) were calculated to assess reproducibility between the repeated eating-occasion grid-derived variables (e.g., numbers of snacks and meals per day, timing of eating occasions) and to assess relative validity by comparing the meal grid and DR-derived summary data separately for weekdays and weekend days.

RESULTS

Reproducibility correlations for eating-occasion variables derived from the eating-occasion grids completed 1 year apart were ≥0.5 for the majority of variables analyzed for both weekdays and weekend days, including numbers of snacks and meals per day and timing of the first and last eating occasions of the day. Relative validity was highest among weekday variables and was ≥0.5 for the majority of variables, with correlations ranging from ρ values of 0.32 (number of meals per day) to 0.68 (hour of the first eating occasion).

CONCLUSIONS

These findings suggest the eating-occasion grid used in CPS-3 has good reproducibility over 1 year and yields estimates comparable to those from a more detailed method of assessment of eating timing and frequency.

Sugar- and Artificially-Sweetened Beverages and Cancer Mortality in a Large U.S. Prospective Cohort

Objectives

Consumption of sugar-sweetened beverages (SSB) may be related to risk of cancer mortality independent of, or indirectly through, its established association with increased body mass, but evidence is inconsistent. We evaluated the association of both SSBs and artificially-sweetened beverages (ASB) with mortality from all cancers combined, BMI-related cancers combined, and 22 individual cancers, with and without adjustment for BMI, among U.S. men and women.

Methods

In 1982,934,777 cancer-free participants in the Cancer Prevention Study-II cohort completed questionnaires including information on usual SSB and ASB consumption. Causes of death were identified through 2016. Multivariable Cox proportional hazards regression models were used to examine associations of both beverage types with cancer mortality.

Results

During follow-up, 135,093 CPS-II participants died from cancer. Consumption of ≥2 SSB drinks/day vs never was associated with obesity-related cancers combined (HR = 1.05, 95% CI 1.01–1.08, p_trend = 0.057), which became null when BMI was included in statistical models. SSBs were associated with increased risks of colorectal (HR = 1.09, 95% CI, 1.02–1.17, p_trend = 0.011), and kidney (HR = 1.17, 95% CI 1.03–1.34, p_trend = 0.06) cancer mortality, even after BMI adjustment, although for kidney cancer the association remained statistically significant only in continuous models. A positive association of ASB consumption with risk of obesity-related cancers combined (HR = 1.05, 95% CI 1.01–1.08, p_trend = .001) became null after controlling for BMI; however, an increased risk of pancreatic cancer remained after BMI adjustment (HR = 1.16, 95% CI 1.07–1.26, p_trend < 0.0001).

Conclusions

SSB consumption may increase risk of obesity-related cancers indirectly through excess body fatness, and of colorectal and kidney cancer mortality independent of obesity. Increased risk of obesity-related cancers with greater ASB intake prior to adjustment for body fatness may reflect confounding by BMI, as ASBs are not considered convincingly related to weight gain. An association of ASB consumption and increased risk of pancreatic cancer deserves further study.

Funding Sources

The American Cancer Society funds the creation, maintenance, and updating of the Cancer Prevention Study-II cohort.

Identifying Novel Susceptibility Genes for Colorectal Cancer Risk From a Transcriptome-Wide Association Study of 125,478 Subjects

BACKGROUND AND AIMS

Susceptibility genes and the underlying mechanisms for the majority of risk loci identified by genome-wide association studies (GWAS) for colorectal cancer (CRC) risk remain largely unknown. We conducted a transcriptome-wide association study (TWAS) to identify putative susceptibility genes.

METHODS

Gene-expression prediction models were built using transcriptome and genetic data from the 284 normal transverse colon tissues of European descendants from the Genotype-Tissue Expression (GTEx), and model performance was evaluated using data from The Cancer Genome Atlas (n = 355). We applied the gene-expression prediction models and GWAS data to evaluate associations of genetically predicted gene-expression with CRC risk in 58,131 CRC cases and 67,347 controls of European ancestry. Dual-luciferase reporter assays and knockdown experiments in CRC cells and tumor xenografts were conducted.

RESULTS

We identified 25 genes associated with CRC risk at a Bonferroni-corrected threshold of P < 9.1 × 10-6, including genes in 4 novel loci, PYGL (14q22.1), RPL28 (19q13.42), CAPN12 (19q13.2), MYH7B (20q11.22), and MAP1L3CA (20q11.22). In 9 known GWAS-identified loci, we uncovered 9 genes that have not been reported previously, whereas 4 genes remained statistically significant after adjusting for the lead risk variant of the locus. Through colocalization analysis in GWAS loci, we additionally identified 12 putative susceptibility genes that were supported by TWAS analysis at P < .01. We showed that risk allele of the lead risk variant rs1741640 affected the promoter activity of CABLES2. Knockdown experiments confirmed that CABLES2 plays a vital role in colorectal carcinogenesis.

CONCLUSIONS

Our study reveals new putative susceptibility genes and provides new insight into the biological mechanisms underlying CRC development.

Abstract 596: Association between an empirically-derived inflammatory lifestyle score and incident colorectal cancer

Inflammation is often suggested as major pathway by which lifestyle influences the development of colorectal cancer (CRC). In the present analysis, we empirically derived an inflammatory lifestyle score (ILS) based on associations of nine lifestyle factors with serum levels of high-sensitivity C-reactive protein (hsCRP) and subsequently examined its association with incident CRC in the Cancer Prevention Study-II Nutrition Cohort. Lifestyle factors other than smoking were chosen a priori from the American Cancer Society’s Guidelines on Nutrition and Physical Activity for Cancer Prevention to include body mass index, physical activity, sedentary time, fruit/vegetable intake, variety of fruits/vegetables consumed, red/processed meat intake, ratio of whole to refined grains consumed, alcohol consumption, and smoking status. Reduced rank regression was used to create sex-specific lifestyle scores that correlate the nine lifestyle factors with hsCRP in a testing subset of 2,707 men and women with no history of cancer at the time of blood draw. In a validation subset (n=540), the derived ILS was positively correlated with serum hsCRP levels (r=0.19, p-value&lt;0.001). Model weights from reduced rank regression in the testing subset were used to calculate the ILS among 114,974 men and women of the cohort for whom hsCRP levels were not available. The association between the ILS and incident CRC was examined using Cox proportional hazards regression to estimate hazard ratios and 95% confidence intervals adjusted for age, sex, education, non-steroidal anti-inflammatory drug use, multivitamin use, postmenopausal hormone therapy, and diabetes status. Starting at baseline in 1999, during a mean follow-up of 12.6 years, 2,082 incident CRC cases were identified (1,649 colon; 433 rectum). Participants in the third and fourth ILS quartiles had 15% (95% CI: 1%, 31%) and 34% (95% CI: 18%, 53%) higher risk of CRC, respectively, than those in the first ILS quartile. A 1-standard deviation increase in the score was associated with 10% higher risk of CRC (95% CI: 1.05, 1.15). The association between the ILS and CRC did not differ across strata of sex or age (&lt;70, ≥70 years). A Lunn-McNeil competing risk model showed no evidence of a differential association of the ILS on CRC organ subtypes (colon vs. rectal). Results support evidence that a lifestyle indicative of high inflammatory potential is associated with an increased risk of developing CRC. To examine other mechanisms by which lifestyle influences CRC risk, additional analyses will use serum levels of C-peptide and hemoglobin A1c. The biomarkers will be examined individually, together (i.e., glucose homeostasis), and in combination with hsCRP (poor metabolic function) to develop lifestyle scores.

Citation Format: Mark Guinter, Susan Gapstur, W. Dana Flanders, Ying Wang, Erika Rees-Punia, Marjorie McCullough, Kassandra I. Alcaraz, Michael Pollak, Peter Campbell. Association between an empirically-derived inflammatory lifestyle score and incident colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 596.

Index-based dietary patterns and colorectal cancer risk: a systematic review

Colorectal cancer (CRC) is the third most common cancer in both men and women in the United States. Various a priori dietary patterns that take into account diet complexity have been associated with CRC risk. This systematic review augments the evidence for an association between CRC risk and the Mediterranean Diet Score (MDS) and the Healthy Eating Index (HEI), and provides new evidence for a novel Dietary Inflammatory Index (DII). Human studies published in English after 31 December 2008 were reviewed. Five case-control studies and 7 prospective cohort studies conducted in the United States and Europe were identified. Five of the studies examined the MDS, 4 examined the HEI, and 4 examined the DII. Comparing highest to lowest score groups, higher MDSs were associated with an 8-54% lower CRC risk, and higher HEI scores were associated with a 20-56% lower CRC risk. More proinflammatory diet scores were associated with a 12-65% higher CRC risk compared with more anti-inflammatory diets in studies that used the DII. The results reported by sex suggested similar associations for men and women. This review builds upon the evidence supporting the association between higher overall diet quality and lower risk of CRC. Increasing scores of MDS and HEI and anti-inflammatory DII scores are characterized by high intake of plant-based foods and low intake of animal products. Future studies in more diverse populations and with consistent scoring calculations are recommended.