Unhealthy dietary habits can contribute to the development of colorectal cancer (CRC). Such habits may also be associated with post-treatment symptoms experienced by CRC survivors. Therefore, we aimed to assess longitudinal associations of post-treatment unhealthy dietary habits, i.e. intake of ultra-processed foods (UPF), red and processed meat, alcohol and sugar-sweetened drinks, with health-related quality of life (HRQoL), fatigue and chemotherapy-induced peripheral neuropathy (CIPN) in CRC survivors from 6 weeks up to 24 months post-treatment. In a prospective cohort among stage I-III CRC survivors (n 396), five repeated home visits from diagnosis up to 24 months post-treatment were executed. Dietary intake was measured by 7-d dietary records to quantify consumption of UPF, red and processed meat, alcohol and sugar-sweetened drinks. HRQoL, fatigue and CIPN were measured by validated questionnaires. We applied confounder-adjusted linear mixed models to analyse longitudinal associations from 6 weeks until 24 months post-treatment. We applied a post hoc time-lag analysis for alcohol to explore the directionality. Results showed that higher post-treatment intake of UPF and sugar-sweetened drinks was longitudinally associated with worsened HRQoL and more fatigue, while higher intake of UPF and processed meat was associated with increased CIPN symptoms. In contrast, post-treatment increases in alcohol intake were longitudinally associated with better HRQoL and less fatigue; however, time-lag analysis attenuated these associations. In conclusion, unhealthy dietary habits are longitudinally associated with lower HRQoL and more symptoms, except for alcohol. Results from time-lag analysis suggest no biological effect of alcohol; hence, the longitudinal association for alcohol should be interpreted with caution.

Current cancer prevention recommendations advise limiting red meat intake to <500 g/week and avoiding consumption of processed meat, but do not differentiate the source of processed meat. We examined the associations of processed meat derived from red v. non-red meats with cancer risk in a prospective cohort of 26 218 adults who reported dietary intake using the Canadian Diet History Questionnaire. Incidence of cancer was obtained through data linkage with Alberta Cancer Registry with median follow-up of 13·3 (interquartile range (IQR) 5·1) years. Multivariable Cox proportional hazards regression models were adjusted for covariates and stratified by age and sex. The median consumption (g/week) of red meat, processed meat from red meat and processed meat from non-red meat was 267·9 (IQR 269·9), 53·6 (IQR 83·3) and 11·9 (IQR 31·8), respectively. High intakes (4th Quartile) of processed meat from red meat were associated with increased risk of gastrointestinal cancer adjusted hazard ratio (AHR): 1·68 (95 % CI 1·09, 2·57) and colorectal cancers AHR: 1·90 (95 % CI 1·12, 3·22), respectively, in women. No statistically significant associations were observed for intakes of red meat or processed meat from non-red meat. Results suggest that the carcinogenic effect associated with processed meat intake may be limited to processed meat derived from red meats. The findings provide preliminary evidence towards refining cancer prevention recommendations for red and processed meat intake.

The World Cancer Research Fund and American Institute for Cancer Research (WCRF/AICR) advise cancer survivors to follow their lifestyle recommendations for cancer prevention. Adhering to these recommendations may have beneficial effects on patient-reported outcomes after a cancer diagnosis, but evidence is scarce. We aimed to assess associations of the individual dietary WCRF/AICR recommendations regarding fruit and vegetables, fibre, fast foods, red and processed meat, sugar-sweetened drinks and alcohol consumption with patient-reported outcomes in colorectal cancer (CRC) survivors. Cross-sectional data of 150 stage I–III CRC survivors, 2–10 years post-diagnosis, were used. Dietary intake was measured by 7-d dietary records. Validated questionnaires were used to measure health-related quality of life (HRQoL), fatigue and neuropathy. Confounder-adjusted linear regression models were used to analyse associations of each WCRF/AICR dietary recommendation with patient-reported outcomes. Higher vegetable intake (per 50 g) was associated with better global QoL (β 2·6; 95 % CI 0·6, 4·7), better physical functioning (3·3; 1·2, 5·5) and lower levels of fatigue (−4·5; −7·6, −1·4). Higher fruit and vegetables intake (per 100 g) was associated with better physical functioning (3·2; 0·8, 5·5) and higher intake of energy-dense food (per 100 kJ/100 g) with worse physical functioning (−4·2; −7·1, −1·2). No associations of dietary recommendations with neuropathy were found. These findings suggest that adhering to specific dietary WCRF/AICR recommendations is associated with better HRQoL and less fatigue in CRC survivors. Although the recommendations regarding healthy dietary habits may be beneficial for the well-being of CRC survivors, longitudinal research is warranted to gain insight into the direction of associations.

Findings for the roles of dairy products, Ca and vitamin D on ovarian cancer risk remain controversial. We aimed to assess these associations by using an updated meta-analysis. Five electronic databases (e.g. PubMed and Embase) were searched from inception to 24 December 2019. Pooled relative risks (RR) with 95 % CI were calculated. A total of twenty-nine case–control or cohort studies were included. For comparisons of the highest v. lowest intakes, higher whole milk intake was associated with increased ovarian cancer risk (RR 1·35; 95 % CI 1·15, 1·59), whereas decreased risks were observed for higher intakes of low-fat milk (RR 0·84; 95 % CI 0·73, 0·96), dietary Ca (RR 0·71; 95 % CI 0·60, 0·84) and dietary vitamin D (RR 0·80; 95 % CI 0·67, 0·95). Additionally, for every 100 g/d increment, increased ovarian cancer risks were found for total dairy products (RR 1·03; 95 % CI 1·01, 1·04) and for whole milk (RR 1·07; 95 % CI 1·03, 1·11); however, decreased risks were found for 100 g/d increased intakes of low-fat milk (RR 0·95; 95 % CI 0·91, 0·99), cheese (RR 0·87; 95 % CI 0·76, 0·98), dietary Ca (RR 0·96; 95 % CI 0·95, 0·98), total Ca (RR 0·98; 95 % CI 0·97, 0·99), dietary vitamin D (RR 0·92; 95 % CI 0·87, 0·97) and increased levels of circulating vitamin D (RR 0·84; 95 % CI 0·72, 0·97). These results show that whole milk intake might contribute to a higher ovarian cancer risk, whereas low-fat milk, dietary Ca and dietary vitamin D might reduce the risk.

The lifestyle recommendations of the World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) are primarily intended for cancer prevention. In the absence of specific recommendations for cancer survivors, we investigated adherence of colorectal cancer (CRC) survivors to the WCRF/AICR lifestyle recommendations and associations with health-related quality of life (HRQoL). The cross-sectional part of the Energy for life after ColoRectal cancer (EnCoRe) study was conducted in 155 CRC survivors (stage I-III), 2–10 years post diagnosis. Dietary intake, physical activity and general body fatness were measured by 7-d food diaries, by questionnaires and accelerometers and BMI, respectively. Adherence to each of the ten WCRF/AICR recommendations was scored as 0 (no/low adherence), 0·5 (moderate adherence) or 1 point (complete adherence), and summed into an overall adherence score (range: 0–10). HRQoL, disability and distress were assessed by validated questionnaires. Associations of the overall WCRF/AICR adherence score with HRQoL outcomes were analysed by confounder-adjusted linear regression. The mean adherence score was 5·1 (sd 1·4, range: 1·5–8·5). In confounder-adjusted models, a higher adherence score was significantly associated with the HRQoL dimension better physical functioning (β per 1 point difference in score: 2·6; 95 % CI 0·2, 5·1) and with less fatigue (β: −3·3; 95 % CI −6·4, −0·1). In conclusion, higher adherence of CRC survivors to WCRF/AICR lifestyle recommendations for cancer prevention was associated with better physical functioning and with less fatigue. This study adds to the limited knowledge on adherence to lifestyle behaviours in CRC survivors and relationships with quality of life. Prospective studies are needed to investigate longitudinal associations.

The evidence on a cancer-protective effect of the Mediterranean diet (MD) is still limited. Therefore, we investigated the association between MD adherence and lung cancer risk. Data were used from 120 852 participants of the Netherlands Cohort Study (NLCS), aged 55–69 years. Dietary habits were assessed at baseline (1986) using a validated FFQ and alternate and modified Mediterranean diet scores (aMED and mMED, respectively), including and excluding alcohol, were calculated. After 20·3 years of follow-up, 2861 lung cancer cases and 3720 subcohort members (case-cohort design) could be included in multivariable Cox regression analyses. High (6–8) v. low (0–3) aMED excluding alcohol was associated with non-significantly reduced lung cancer risks in men and women with hazard ratios of 0·91 (95 % CI 0·72, 1·15) and 0·73 (95 % CI 0·49, 1·09), respectively. aMED-containing models generally fitted better than mMED-containing models. In never smokers, a borderline significant decreasing trend in lung cancer risk was observed with increasing aMED excluding alcohol. Analyses stratified by the histological lung cancer subtypes did not identify subtypes with a particularly strong inverse relation with MD adherence. Generally, the performance of aMED and World Cancer Research Fund/American Institute for Cancer Research dietary score variants without alcohol was comparable. In conclusion, MD adherence was non-significantly inversely associated with lung cancer risk in the NLCS. Future studies should focus on differences in associations across the sexes and histological subtypes. Furthermore, exclusion of alcohol from MD scores should be investigated more extensively, primarily with respect to a potential role of the MD in cancer prevention.

Diet, nutritional status and lifestyle practices are significant determinants of the risk of certain cancers. In 1997 The World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) developed a series of evidence-based recommendations to help reduce the population and individual risk of cancer. However, guidance for evaluating concordance or compliance with these recommendations is limited. To illustrate the challenges in evaluation, four publications were reviewed that explored the task of creating operative criteria from which to assess concordance with the tenets of the WCRF/AICR recommendations. Three documents dealt with secondary analysis, whereas one was a prospective inquiry, with procedures and instruments designed to obtain responses to WCRF/AICR cancer-prevention specification. One considered only population-goal criteria, and two dealt implicitly or explicitly with criteria at both population and individual levels. The assessment approaches used by the authors were compared with alternative semantic and conceptual interpretations of the WCRF/AICR population goals and individual guidelines. Attempts to develop operative criteria for assessment of concordance (reflecting either a more superficial or more in-depth parsing of recommendations) have been inconsistent. The results indicate that the language of the WCRF/AICR leaves a certain degree of semantic ambiguity for evaluation purposes. Future design of prospective studies for analyses of behaviours and relevant exposures (including those reported in the 2007 WCRF/AICR report) should carefully consider evaluation criteria and fully document detailed methodology.