Background and objective:
The COVID-19 pandemic significantly impacted behaviours and activities of daily life worldwide. Public health restrictions that were necessary to control the virus resulted in changes in health behaviours. This includes changes in established cancer risk factors, defined for this review as smoking, alcohol consumption, decreased physical activity, increased sedentary behavior, decreased consumption of fruits and vegetables, and increased red meat/meat intake. The objective of this umbrella review was to assess how the COVID-19 pandemic, compared to pre-pandemic, impacted the prevalence of behavioral cancer risk factors among community-based adults.

Methods:
On October 12th 2022, five databases (PubMed, Web of Science, MEDLINE, Embase and the Cochrane Database of Systematic Reviews) were searched onwards of January 2020. Studies were eligible for inclusion if they were a systematic review, with or without meta-analysis, and if they examined the change in an identified cancer risk factor during the COVID-19 pandemic. Studies were excluded if they did not focus on the general adult population. Five reviewers independently assessed the studies for eligibility, extracted data and conducted critical appraisal using the AMSTAR-2.

Results:
After screening, 31 reviews were included for smoking (n=3), alcohol (n=9), physical activity (n=14), sedentary behaviour (n=8), fruits and vegetables (n=6), and red meat/meat (n=5). Preliminary results based on low quality heterogeneous evidence did not suggest a consistent increase in smoking and alcohol use. Similarly, the evidence was mixed regarding fruit, vegetable and red meat/meat consumption and was dependent on study population. In contrast, the evidence consistently indicated a decrease in physical activity and an increase in sedentary behavior during the pandemic compared to the pre-pandemic period.

Conclusions:
The results of our review suggest the COVID-19 pandemic had a mixed impact on cancer risk factors. Public health interventions should concentrate on mitigating negative consequences of changes in cancer risk post-pandemic.