Digital health behaviour change interventions targeting physical activity and diet in cancer survivors: a systematic review and meta-analysis

Purpose: The number of cancer survivors has risen substantially due to improvements in early diagnosis and treatment. Health behaviours such as physical activity (PA) and diet can reduce recurrence and mortality, and alleviate negative consequences of cancer and treatments. Digital behaviour change interventions (DBCIs) have the potential to reach large numbers of cancer survivors. Methods: We conducted a systematic review and meta-analyses of relevant studies identified by a search of Medline, EMBASE, PubMed and CINAHL. Studies which assessed a DBCI with measures of PA, diet and/or sedentary behaviour were included. Results: 15 studies were identified. Random effects meta-analyses showed significant improvements in moderate-vigorous PA (7 studies; mean difference (MD) = 41 minutes per week; 95% CI: 12, 71) and body mass index (BMI)/weight (standardised mean difference (SMD) = -0.23; 95% CI: -0.41, -0.05). There was a trend toward significance for reduced fatigue and no significant change in cancer-specific quality of life (QoL). Narrative synthesis revealed mixed evidence for effects on diet, generic QoL and self-efficacy and no evidence of an effect on mental health. Two studies suggested improved sleep quality. Conclusions: DBCIs may improve PA and BMI among cancer survivors and there is mixed evidence for diet. The number of included studies is small and risk of bias and heterogeneity was high. Future research should address these limitations with large, high-quality RCTs, with objective measures of PA and sedentary time. Implications for cancer survivors: Digital technologies offer a promising approach to encourage health behaviour change among cancer survivors

Sedentary Behaviour and Chronic Disease: Mechanisms and Future Directions

Recent updates to national physical activity guidelines now highlight the importance of reducing sedentary time. However, at present only general recommendations are possible (i.e. “Sit less, move more”). There remains a need to investigate the strength, temporality, specificity and dose-response nature of sedentary behaviour associations with chronic disease, along with potential underlying mechanisms. Stemming from a recent research workshop organised by the Sedentary Behaviour Council themed ‘‘Sedentary behaviour mechanisms—biological and behavioural pathways linking sitting to adverse health outcomes”, this paper aims to: 1) discuss existing challenges and scientific discussions within this advancing area of science, 2) highlight and discuss emerging areas of interest, and 3) point to pertinent future directions. A brief knowledge update is provided, reflecting upon current and evolving thinking/discussions, and the rapid accumulation of new evidence linking sedentary behaviour to chronic disease. Succinct research 'action-points' are made at the end of each section – spanning from measurement systems and analytic methods, genetic epidemiology, causal mediation and experimental studies, to biological and behavioural determinants and mechanisms. A better understanding of whether and how sedentary behaviour is causally related with chronic disease will allow for more meaningful conclusions in the future and assist in refining both clinical and public health policies/recommendations.This work was supported by the UK Medical Research Council [grant number MC_UU_12015/3 and MC_UU_12015/1]. PCD and DWD are supported by National Health and Medical Research Council of Australia (NHMRC) Fellowships (#1142685 and #1078360). E.H. van Roekel was financially supported by Wereld Kanker Onderzoek Fonds (WKOF), as part of the World Cancer Research Fund International grant programme (grant number 2016/1620). BL is supported by a Mid-Career Research Fellowship from the Victorian Cancer Agency. AD is supported by the National Institute for Health Research (NIHR) Oxford Biomedical Research Centre (BRC). The views expressed are those of the author(s) and not necessarily those of the UK NHS, NIHR or Department of Health

Linking Physical Activity to Breast Cancer via Sex Hormones, Part 1: The Effect of Physical Activity on Sex Steroid Hormones

The effect of physical activity on breast cancer risk may be partly mediated by sex steroid hormones. This review synthesized and appraised the evidence for an effect of physical activity on sex steroid hormones. Systematic searches were performed using MEDLINE (Ovid), EMBASE (Ovid), and SPORTDiscus to identify experimental studies and prospective cohort studies that examined physical activity and estrogens, progestins, and/or androgens, as well as sex hormone binding globulin (SHBG) and glucocorti-coids in pre- and postmenopausal women. Meta-analyses were performed to generate effect estimates. Risk of bias was assessed, and the GRADE system was used to appraise quality of the evidence. Twenty-eight randomized controlled trials (RCT), 81 nonrandomized interventions, and six observational studies were included. Estrogens, progesterone, and androgens mostly decreased, and SHBG increased, in response to physical activity. Effect sizes were small, and evidence quality was graded moderate or high for each outcome. Reductions in select sex steroid hormones following exercise supports the biological plausibility of the first part of the physical activity-sex hormone-breast cancer pathway. The con-firmed effect of physical activity on decreasing circulating sex steroid hormones supports its causal role in preventing breast cancer