Dietary intake of fiber, whole grains and risk of colorectal cancer: An updated analysis according to food sources, tumor location and molecular subtypes in two large US cohorts
HE X. et al (2019). Int J Cancer.
There is a long-standing hypothesis that higher intake of dietary fibre reduces the risk of colorectal cancer (CRC), however epidemiologic evidence remains inconclusive. Data are limited on the influence of the food source of the fibre and heterogeneity of the tumour. This study prospectively followed up 90,869 women for CRC incidence in from the Nurses’ Health Study (1980–2012) and 47,924 men from the Health Professionals Follow up Study (1986–2012). Participants completed a validated food frequency questionnaire every 4 years where participants were asked how often, on average, they consumed foods of a standard portion size during the previous 4 years. Cox proportional hazards regression was used to examine the associations with CRC risk for total dietary fibre, cereal, fruit and vegetable fibre and whole grains.
The study found that intake of total dietary fibre was not associated with reduced CRC risk, after multivariable adjustment, in women (HR:1.17; 95% CI:0.92–1.48) or men (HR:0.90; 95% CI:0.67–1.21). Higher intake of cereal fibre and whole grains was associated with reduced CRC
risk in men with an HR of 0.75(95% CI:0.57–1.00) and 0.72(95% CI:0.54– 0.96), respectively. No heterogeneity was detected by tumour subsite or molecular markers (p>0.05).
The authors concluded that higher intake of total dietary fibre within the range of a typical American diet is unlikely to substantially reduce CRC risk. The potential benefit of cereal fibre and whole grains in men warrants further investigation.
Association of Survival with Adherence to the American Cancer Society Nutrition and Physical Activity Guidelines for Cancer Survivors after Colon Cancer Diagnosis: The CALGB 89803/Alliance Trial
VAN BLARIGAN EL. et al (2018). JAMA Oncol.
The American Cancer Society (ACS) Nutrition and Physical Activity Guidelines for Cancer Survivors include; maintaining a healthy body weight, physical activity, and a diet that includes vegetables, fruits, and whole grains. This prospective cohort study examined 992 patients with stage III colon cancer who were enrolled in the CALGB 89803 randomized adjuvant chemotherapy trial from 1999 through 2001. Authors assigned an ACS guidelines score for each participant based on; body mass index, physical activity, and intake of vegetables, fruits, whole grains, and red/processed meats (score range, 0-6, with higher score indicating healthier behaviours). Secondarily, they examined a score that included alcohol intake in addition to the other factors (range, 0-8). Lifestyle was assessed during, and 6 months after, chemotherapy. Compared with patients with a 0 to 1 ACS guidelines score, patients with a 5 to 6 score had a 42% reduced risk of death during the study period (HR, 0.58; 95% CI, 0.34-0.99; P =0 .01) and improved disease-free survival (HR, 0.69; 95% CI, 0.45-1.06; P = 0.03). Results were strengthened when alcohol consumption was included in the score, comparing patients with high scores (6-8) vs patients with low scores (0-2), adjusted HRs were; overall survival 0.49 (95% CI, 0.32-0.76; P = 0.002), disease free survival 0.58 (95% CI, 0.40, 0.84; P = 0.01) and recurrence-free survival 0.64 (95% CI,0.44-0.94; P = 0.05).
The authors concluded that having a healthy body weight, being physically active, and eating a diet rich in vegetables, fruits, and whole grains after diagnosis of stage III colon cancer was associated with a longer survival.
Systematic review and meta analysis of maintenance of physical activity behavior change in cancer survivors
GRIMMETT C. et al (2019). IJBNPA
There is good evidence that regular physical activity can improve both health and wellbeing after a cancer diagnosis. Furthermore, accumulating observational evidence suggests regular physical activity may reduce cancer recurrence and mortality and prolong disease-free
survival. This systematic review and meta-analysis evaluated the effectiveness of interventions in supporting maintenance of physical activity behaviour change in adults diagnosed with cancer, and explores which intervention components and contextual features are associated
with effectiveness. Twenty seven randomised controlled trials (RCTs) were included, 19 of which were pooled in a meta-analysis. Within-group pre-post intervention analysis yielded a mean increase of 27.48 (95% CI = 11.48-43.49) mins/wk. of moderate to vigorous physical activity (MVPA) in control groups and 65.30 (95% CI = 45.59–85.01) mins/wk. of MVPA in the intervention groups. Ineffective interventions tended
to include older populations with existing physical limitations, fewer contacts with participants, and were less likely to include a supervised element or the behaviour change techniques (BCTs) of ‘action planning’, ‘graded tasks’ and ‘social support (unspecified)’. Included studies were biased towards inclusion of younger, female, well-educated and white populations who were already engaging in some physical activity.
The authors concluded that existing interventions are effective in achieving modest increases in physical activity, at least 3 months post-intervention completion. However, study samples were not representative of typical cancer populations.