Table 2.
Colorectal cancer mortality according to postdiagnosis physical activity levels in all cases or in strata of quartiles of T cell densities
| Colorectal cancer-specific mortality HR for a quartile-unit increase of postdiagnosis physical activity levels |
Overall mortality HR for a quartile-unit increase of postdiagnosis physical activity levels |
||||||
|---|---|---|---|---|---|---|---|
| Characteristic | No. of cases | No. of events | Univariate HR (95% CI)* | Multivariable HR (95% CI)*† | No. of events | Univariate HR (95% CI)* | Multivariable HR (95% CI)*† |
| All colorectal cancer cases | 470 | 100 | 0.77 (0.64 to 0.92) | 0.78 (0.64 to 0.95) | 275 | 0.77 (0.69 to 0.86) | 0.83 (0.75 to 0.93) |
| CD3+ cell density | |||||||
| Quartile 1 (lowest) | 111 | 30 | 0.61 (0.42 to 0.88) | 0.56 (0.38 to 0.83) | 69 | 0.75 (0.59 to 0.95) | 0.76 (0.62 to 0.93) |
| Quartile 2 | 111 | 23 | 0.78 (0.53 to 1.15) | 0.80 (0.54 to 1.18) | 64 | 0.68 (0.55 to 0.84) | 0.72 (0.58 to 0.89) |
| Quartile 3 | 112 | 25 | 0.75 (0.49 to 1.14) | 0.73 (0.47 to 1.11) | 68 | 0.80 (0.63 to 1.02) | 0.83 (0.65 to 1.06) |
| Quartile 4 (highest) | 111 | 15 | 1.04 (0.73 to 1.49) | 1.14 (0.79 to 1.65) | 60 | 0.85 (0.67 to 1.08) | 0.96 (0.76 to 1.21) |
| Pinteraction‡ | .004 | <.001 | .35 | .17 | |||
| CD8+ cell density | |||||||
| Quartile 1 (lowest) | 110 | 34 | 0.67 (0.48 to 0.92) | 0.66 (0.47 to 0.94) | 66 | 0.72 (0.56 to 0.92) | 0.78 (0.59 to 1.02) |
| Quartile 2 | 109 | 23 | 0.84 (0.57 to 1.23) | 0.81 (0.56 to 1.18) | 65 | 0.81 (0.65 to 1.00) | 0.80 (0.65 to 0.99) |
| Quartile 3 | 109 | 18 | 0.58 (0.37 to 0.90) | 0.56 (0.33 to 0.95) | 59 | 0.62 (0.49 to 0.79) | 0.75 (0.59 to 0.95) |
| Quartile 4 (highest) | 109 | 19 | 1.03 (0.71 to 1.51) | 1.02 (0.67 to 1.56) | 64 | 0.87 (0.69 to 1.10) | 0.86 (0.70 to 1.05) |
| Pinteraction‡ | .060 | .14 | .22 | .45 | |||
| CD45RO+ cell density | |||||||
| Quartile 1 (lowest) | 113 | 33 | 0.95 (0.69 to 1.31) | 0.86 (0.62 to 1.19) | 73 | 0.73 (0.57 to 0.93) | 0.77 (0.62 to 0.95) |
| Quartile 2 | 113 | 34 | 0.70 (0.49 to 1.01) | 0.64 (0.44 to 0.95) | 69 | 0.77 (0.60 to 0.97) | 0.79 (0.62 to 0.99) |
| Quartile 3 | 113 | 19 | 0.61 (0.41 to 0.91) | 0.65 (0.42 to 1.02) | 63 | 0.74 (0.59 to 0.91) | 0.80 (0.65 to 1.00) |
| Quartile 4 (highest) | 112 | 10 | 0.87 (0.46 to 1.63) | 0.88 (0.44 to 1.72) | 60 | 0.82 (0.66 to 1.03) | 0.91 (0.74 to 1.13) |
| Pinteraction‡ | .81 | .84 | .76 | .80 | |||
| FOXP3+ cell density | |||||||
| Quartile 1 (lowest) | 107 | 32 | 0.71 (0.50 to 1.00) | 0.75 (0.51 to 1.10) | 76 | 0.67 (0.53 to 0.84) | 0.74 (0.58 to 0.94) |
| Quartile 2 | 106 | 23 | 0.69 (0.48 to 0.99) | 0.72 (0.48 to 1.08) | 67 | 0.71 (0.58 to 0.87) | 0.75 (0.61 to 0.92) |
| Quartile 3 | 106 | 20 | 0.94 (0.62 to 1.44) | 1.02 (0.68 to 1.51) | 56 | 0.98 (0.75 to 1.27) | 1.06 (0.85 to 1.33) |
| Quartile 4 (highest) | 107 | 13 | 0.66 (0.42 to 1.03) | 0.64 (0.40 to 1.03) | 49 | 0.73 (0.56 to 0.94) | 0.77 (0.61 to 0.98) |
| Pinteraction‡ | .46 | .33 | .73 | .31 | |||
IPW was applied to reduce a bias due to the availability of questionnaire data after cancer diagnosis (see Statistical Analysis subsection for details). CI = confidence interval; HR = hazard ratio; IPW = inverse probability weighting.
The multivariable sex-stratified IPW-adjusted Cox regression model initially included age, year of diagnosis, family history of colorectal cancer, body mass index, prediagnosis physical activity, tumor location, tumor differentiation, disease stage, microsatellite instability, CpG island methylator phenotype, long interspersed nucleotide element-1 methylation level, KRAS mutation, BRAF mutation, PIK3CA mutation, nuclear CTNNB1 (beta-catenin) expression, PTGS2 (cyclooxygenase-2) expression, and IRS1 expression. A backward elimination with a threshold of P equal to .05 was used to select variables for the final models. The variables that remained in the final models for analyses stratified by CD3+ cell density are described in Appendix Table A2.
P interaction was calculated using the Wald test for the cross-product of postdiagnosis physical activity levels (the median value of each decile category) and each T cell subset (the median value of each decile category) in the sex-stratified IPW-adjusted Cox regression model.