Summary of evidence grading for meta-analyses of cohort studies associating physical activity and risk of developing or dying from cancer
| Evidence | Criteria used | Decreased risk | |
| Any physical activity | Recreational 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‡ | None | Colon cancer, inc. or mort. |
| Highly suggestive | *P<10−6; >1000 cases; P<0.05 of the largest study in a meta-analysis | Breast cancer, inc. and all cancer, mort. | None |
| Suggestive | *P<10−3; >1000 cases | Colon cancer, inc. or mort, lung inc. and endometrial, inc. | All cancer, mort. and lung, inc. |
| Weak | *P<0.05 | Meningioma, 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.