We conducted a systematic literature review and meta-analysis of observational studies investigating adherence to the 2007 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) lifestyle recommendations for cancer prevention and health outcomes. We searched PubMed and the in-house database of the WCRF Continuous Update Project for publications up to June 2019. Cross-sectional studies were only narratively reviewed given their heterogeneity while findings of cohort/case-control studies were synthesized in umbrella reviews and meta-analyses. Summary relative risks (RRs) and 95% confidence intervals (CI) were estimated using a random-effects model when at least two studies reported results on a specific outcome. Thirty-eight articles (17 prospective, 8 case-control, and 13 cross-sectional studies) were included. The summary RR per each point increment in the 2007 WCRF/AICR score was 0.90 (95% CI: 0.87-0.93, n = 11) for breast cancer, regardless of hormone receptor and menopausal status, 0.86 (95% CI: 0.82-0.89, n = 10) for colorectal cancer, and 0.93 (95% CI: 0.89-0.96, n = 2) for lung cancer risk. No statistically significant associations were reported for prostate (n = 6) and pancreatic cancers (n = 2). Adherence to the recommendations was associated with lower overall mortality (RR = 0.90, 95% CI 0.84-0.96, n = 3) and cancer-specific mortality (RR = 0.91, 95% CI 0.89-0.92; n = 3) in healthy populations, as well as with higher survival in cancer patients (n = 2). In cross-sectional studies, a healthier plasma marker profile and lower cancer risk factors in the general population and a better health status and quality of life in cancer patients/survivors were reported. Adhering to the 2007 WCRF/AICR recommendations is associated with lower risks of cancer incidence, namely breast and colorectal cancers, and mortality. Primary prevention of cancer should emphasize modification of multiple lifestyle factors. Upcoming studies examining the recently updated 2018 guidelines will further clarify such associations.

Diet is a modifiable risk factor for several neoplasms but evidence for chronic lymphocytic leukemia is sparse. Previous studies examining the association between single-food items and chronic lymphocytic leukemia risk have yielded mixed results, while few studies have been conducted on overall diet, reporting inconclusive findings. This study aimed to evaluate the association between adherence to three dietary patterns and chronic lymphocytic leukemia in the MCC-Spain case-control study. Anthropometric, sociodemographic, medical and dietary information was collected for 369 chronic lymphocytic leukemia cases and 1,605 controls. Three validated dietary patterns - Western, Prudent and Mediterranean - were reconstructed in the MCC-Spain data. The association between adherence to each dietary pattern and chronic lymphocytic leukemia was assessed, overall and by Rai stage, using mixed logistic regression models adjusted for potential confounders. High adherence to a Western dietary pattern (i.e high intakes of high-fat dairy products, processed meat, refined grains, sweets, caloric drinks, and convenience food) was associated with chronic lymphocytic leukemia (ORQ4vs.Q1=1.63 (95%CI 1.11; 2.39); p-trend=0.02; OR 1-SD increase=1.19 (95%CI 1.03; 1.37)), independently of Rai stages. No differences in the association were observed by sex, body mass index, energy intake, tobacco, physical activity, working on a farm and family history of hematologic malignancies. No associations were observed for Mediterranean and Prudent dietary patterns and chronic lymphocytic leukemia. This study provides the first evidence for an association between a Western dietary pattern and chronic lymphocytic leukemia, suggesting that a proportion of chronic lymphocytic leukemia cases could be prevented by modifying dietary habits. Further research, especially with a prospective design, is warranted to confirm these findings.

There are many different methods used to measure the degree of adherence to a Mediterranean diet (MD), limiting comparison and interpretation of their results. The concordance between different methodologies has been questioned and their evaluation recommended. The aim of this study was to evaluate the agreement among five indexes that measure adherence to a Mediterranean dietary pattern. The study population included healthy adults selected in the Multi-Case Control Spain (MCC-Spain) study recruited in 12 provinces. A total of 3640 controls were matched to cases by age and sex. To reach the aim, the following scores of adherence to a Mediterranean dietary pattern were calculated: Mediterranean diet score (MDS), alternative Mediterranean diet (aMED), relative Mediterranean diet (rMED), dietary score (DS) and literature-based adherence score (LBAS). The relative frequency of subjects with a high level of adherence to a MD varied from 22% (aMED index) to 37.2% (DS index). Similarly, a high variability was observed for the prevalence of a low level of MD: from 24% (rMED) to 38.4% (aMED). The correlation among MDS, aMED and rMED indexes was moderate, except for MDS and aMED with a high coefficient of correlation 0.75 (95% CI 0.74–0.77). The Cohen’s Kappa coefficient among indexes showed a moderate–fair concordance, except for MDS and aMED with a 0.56 (95% CI 0.55–0.59) and 0.67 (95% CI 0.66–0.68) using linear and quadratic weighting, respectively. The existing MD adherence indexes measured the same, although they were based on different constructing algorithms and varied in the food groups included, leading to a different classification of subjects. Therefore, concordance between these indexes was moderate or low.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults in Western countries. Its etiology is largely unknown but increasing incidence rates observed worldwide suggest that lifestyle and environmental factors such as diet might play a role in the development of CLL. Hence, we hypothesized that the consumption of ultra-processed food and drinks (UPF) might be associated with CLL. Data from a Spanish population-based case-control study (MCC-Spain study) including 230 CLL cases (recruited within three years of diagnosis) and 1634 population-based controls were used. The usual diet during the previous year was collected through a validated food frequency questionnaire and food and drink consumption was categorized using the NOVA classification scheme. Logistic regression models adjusted for potential confounders were used. Overall, no association was reported between the consumption of UPF and CLL cases (OR per each 10% increase of the relative contribution of UPF to total dietary intake = 1.09 (95% CI: 0.94; 1.25)), independently of the Rai stage at diagnosis. However, when analyses were restricted to cases diagnosed within <1 year (incident), each 10% increment in the consumption of UPF was associated with a 22% higher odds ratio of CLL (95% CI: 1.02, 1.47) suggesting that the overall results might be affected by the inclusion of prevalent cases, who might have changed their dietary habits after cancer diagnosis. Given the low number of cases in the subgroup analyses and multiple tests performed, chance findings cannot totally be ruled out. Nonetheless, positive associations found in CLL incident cases merit further research, ideally in well-powered studies with a prospective design.