TABLE 2.
Recreational physical activity after diagnosis and breast cancer‐specific mortality, summary of results
| Heterogeneity | Small‐study effects | ||||||
|---|---|---|---|---|---|---|---|
| Analysis | Number of studies (number of publications) | Number of events a | Summary HR (95% CI) random‐effects | Summary HR (95% CI) fixed‐effect | I 2% (95% CI) | Q value, df, Q P‐value | Egger's P‐value |
| Dose–response meta‐analyses (HR per 10 MET‐h/week) | |||||||
| Main analysis (all‐studies) | 11 (8) | 1632 | 0.86 (0.77‐0.96) | 0.93 (0.89‐0.96) | 65 (28‐83) | 22.7, 8, .01 | .05 |
| Stratified by menopausal status | |||||||
| Postmenopausal | 4 (4) | 476 | 0.84 (0.68‐1.04) | 0.97 (0.91‐1.03) | 65 (0‐88) | 8.6, 3, .04 | |
| Stratified by timing of physical activity assessment in relation to cancer treatment | |||||||
| After the end of primary cancer treatment | 3 (3) | 585 | 0.91 (0.80‐1.04) | 0.95 (0.90‐1.01) | 69 (0‐91) | 6.53, 2, .04 | |
| Stratified by adjustment variables | |||||||
| Adjusted for stage: Yes | 9 (6) | 1500 | 0.90 (0.82‐0.98) | 0.93 (0.89‐0.97) | 61 (3‐84) | 12.7, 5, .03 | – |
| Adjusted for stage: No | 2 (2) | 132 | 0.65 (0.37‐1.14) | 0.74 (0.56‐0.98) | 73 (10‐92) | 7.5, 2, .02 | – |
| Adjusted for treatments: Yes | 7 (4) | 1149 | 0.90 (0.85‐0.95) | 0.90 (0.85‐0.95) | 1 (0‐90) | 2, 2, .37 | – |
| Adjusted for treatments: No | 4 (4) | 483 | 0.70 (0.50‐0.96) | 0.79 (0.67‐0.93) | 63 (3‐86) | 11, 4, .03 | – |
| Adjusted for smoking: Yes | 6 (3) | 1323 | 0.90 (0.85‐0.95) | 0.90 (0.85‐0.95) | 0 (0‐86) | 1.4, 2, .49 | – |
| Adjusted for smoking: No | 5 (5) | 309 | 0.77 (0.59‐0.99) | 0.96 (0.90‐1.02) | 73 (39‐88) | 18.8, 5, .002 | – |
| Adjusted for alcohol: Yes | 2 (2) | 352 | 0.84 (0.69‐1.02) | 0.84 (0.69‐1.02) | 0 (NA) | 0.84, 1, .36 | – |
| Adjusted for alcohol: No | 9 (7) | 1280 | 0.87 (0.76‐0.98) | 0.93 (0.89‐0.97) | 71 (37‐87) | 20.8, 6, .002 | – |
| Stratified by median deaths | |||||||
| Less than median deaths | 4 (4) | 200 | 0.72 (0.50‐1.05) | 0.98 (0.92‐1.04) | 73 (32‐89) | 14.8, 4, .01 | – |
| More than median deaths | 8 (4) | 1432 | 0.89 (0.83‐0.94) | 0.89 (0.85‐0.94) | 5 (0‐85) | 3.2, 3, .37 | – |
| Highest vs lowest meta‐analyses | |||||||
| Main analysis (all‐studies) | 12 (9) | 1827 | 0.60 (0.47‐0.77) | 0.66 (0.57‐0.77) | 42 (0‐72) | 16, 9, .08 | 0.11 |
| Stratified by BMI | |||||||
| BMI < 25 (kg/m2) b | 3 (3) | 185 | 0.47 (0.20‐1.10) | 0.51 (0.35‐0.75) | 76 (21‐93) | 8.36, 2, .02 | – |
| BMI ≥ 25 (kg/m2) b | 3 (3) | 196 | 0.51 (0.35‐0.74) | 0.51 (0.36‐0.73) | 10 (0‐91) | 2.23, 2, .33 | – |
| Stratified by menopausal status | |||||||
| Premenopausal | 1 (1) | 58 | 0.58 (0.32‐1.05) | 0.58 (0.32‐1.05) | – | – | |
| Postmenopausal | 5 (5) | 682 | 0.71 (0.59‐0.87) | 0.71 (0.59‐0.87) | 0 (0‐67) | 2.5, 4, .65 | – |
| Stratified by adjustment variables | |||||||
| Adjusted for stage: Yes | 9 (6) | 1500 | 0.71 (0.60‐0.83) | 0.71 (0.60‐0.83) | 0 (0‐66) | 3.7, 5, .59 | – |
| Adjusted for stage: No | 3 (3) | 327 | 0.40 (0.17‐0.91) | 0.47 (0.33‐0.67) | 74 (28‐91) | 11, 3, .01 | – |
| Adjusted for treatments: Yes | 9 (5) | 1344 | 0.56 (0.38‐0.82) | 0.64 (0.53‐0.78) | 50 (0‐82) | 7.9, 4, .10 | – |
| Adjusted for treatments: No | 3 (4) | 483 | 0.58 (0.35‐0.97) | 0.68 (0.53‐0.87) | 66 (10‐87) | 12, 4, .02 | – |
| Adjusted for smoking: Yes | 6 (3) | 1323 | 0.74 (0.62‐0.87) | 0.74 (0.62‐0.87) | 0 (0‐79) | 0.98, 2, .61 | – |
| Adjusted for smoking: No | 6 (6) | 504 | 0.47 (0.30‐0.74) | 0.46 (0.34‐0.63) | 49 (0‐79) | 11.8, 6, .07 | – |
| Adjusted for alcohol: Yes | 2 (2) | 352 | 0.74 (0.56‐0.99) | 0.74 (0.56‐0.99) | 0 (NA) | 0.97, 1, .32 | – |
| Adjusted for alcohol: No | 10 (8) | 1475 | 0.52 (0.35‐0.77) | 0.62 (0.52‐0.75) | 60 (13‐82) | 17, 7, .01 | – |
| Stratified by median deaths | |||||||
| Less than median deaths | 5 (5) | 286 | 0.56 (0.34‐0.91) | 0.57 (0.42‐0.79) | 47 (0‐79) | 9.4, 5, .09 | – |
| More than median deaths | 7 (4) | 1541 | 0.60 (0.42‐0.85) | 0.68 (0.57‐0.81) | 68 (7‐89) | 9.33, 3, .03 | – |
| Stratified by timing of physical activity assessment after in relation to cancer treatment | |||||||
| After the end of primary cancer treatment | 4 (4) | 687 | 0.83 (0.61‐1.12) | 0.94 (0.90‐0.98) | 0 | 0.41, 3, .94 | – |
| Stratified by physical activity intensity | |||||||
| Moderate | 2 (2) | 211 | 0.59 (0.38‐0.90) | 0.59 (0.38‐0.89) | 4 | 1.04, 1, .31 | – |
| Moderate to vigorous | 3 (3) | 528 | 0.77 (0.60‐0.99) | 0.77 (0.60‐0.99) | 0 (0‐83) | 1.20, 2, .52 | – |
| Vigorous | 2 (2) | 211 | 1.10 (0.74‐1.63) | 1.10 (0.74‐1.63) | 0 (n/a) | 0.00, 1, 1.00 | – |
Note: Where the number of studies differs from the number of publications is because we have used the pooling project ABCPP in analyses.
Abbreviations: BMI, body mass index; CI, confidence interval; df, degrees of freedom; HR, hazard ratio; MET, metabolic equivalent of task.
a
Not all studies that are included in the analyses reported the number of events. Bradshaw 2014 (LIBCSP) did not provide the number of events for each BMI subgroup.
b
Bradshaw 2014 (LIBCSP) is used in analysis.