Table 1

Summary of evidence grading for meta-analyses of cohort studies associating physical activity and risk of developing or dying from cancer

EvidenceCriteria usedDecreased risk
Any physical activityRecreational physical activity
Strong*P<10−6; >1000 cases; P<0.05 of the largest study in a meta-analysis; I2<50%; no small study effect†; prediction interval excludes the null value; no excess significance bias‡NoneColon cancer, inc. or mort.
Highly suggestive*P<10−6; >1000 cases; P<0.05 of the largest study in a meta-analysisBreast cancer, inc. and all cancer, mort.None
Suggestive*P<10−3; >1000 casesColon cancer, inc. or mort, lung inc. and endometrial, inc.All cancer, mort. and lung, inc.
Weak*P<0.05Meningioma, inc. or mort, multiple cancer sites, inc. or mort, pancreas, inc.Oesophageal, inc. and meningioma, inc. or mort.
  • *P indicates the P values of the meta-analysis random effects model.

  • †Small study effect is based on the P value from the Egger’s regression asymmetry test (P≤0.1) where the random effects summary estimate was larger compared with the point estimate of the largest study (smallest SE) in a meta-analysis.

  • ‡Based on the P value (P>0.1) of the excess significance test using the largest study (smallest SE) in a meta-analysis as the plausible effect size.

  • inc., incidence; mort., mortality.