Table 3.
Multivariable logistic regression for secondary tumor.
| Secondary tumor=Yes |
|||||
|---|---|---|---|---|---|
| Covariate** | Level | N* | Odds ratio (95% CI) | OR P-value | Type 3 P-value |
| Treatment cohorts | Proton | 3416 | 0.49 (0.40-0.60) | <.001 | <.001 |
| SBRT | 9247 | 0.57 (0.51-0.63) | <.001 | ||
| IMRT | 121 027 | - | - | ||
| Race-ethnic groups | NH-White | 101 935 | 1.20 (1.13-1.28) | <.001 | <.001 |
| Asian-Indians-Pac | 2962 | 0.90 (0.77-1.06) | .211 | ||
| Hispanic | 5806 | 0.80 (0.70-0.90) | <.001 | ||
| Other/Unknown | 1658 | 0.48 (0.36-0.63) | <.001 | ||
| NH-Black | 21 329 | - | - | ||
| Facility type | Academic/Research program | 40 311 | 0.87 (0.83-0.91) | <.001 | <.001 |
| Nonacademic/Research program | 93 379 | - | - | ||
| Facility location | Pacific | 14 934 | 0.95 (0.89-1.03) | .199 | .005 |
| Mountain | 4072 | 0.87 (0.76-0.98) | .028 | ||
| Central | 49 281 | 1.04 (1.00-1.09) | .062 | ||
| Eastern | 65 403 | - | - | ||
| Charlson-Deyo score | 2+ | 4532 | 1.20 (1.08-1.33) | <.001 | <.001 |
| 1 | 16 071 | 1.15 (1.08-1.22) | <.001 | ||
| 0 | 113 087 | - | - | ||
| T stage | T2 | 38 940 | 1.14 (1.09-1.19) | <.001 | <.001 |
| Unknown | 510 | 1.02 (0.73-1.43) | .893 | ||
| T3 | 6299 | 1.00 (0.90-1.10) | .946 | ||
| T4 | 457 | 1.14 (0.82-1.59) | .433 | ||
| T1 | 87 484 | - | - | ||
| Gleason score | 7 | 60 554 | 0.87 (0.83-0.92) | <.001 | <.001 |
| 8-10 | 33 967 | 0.82 (0.77-0.87) | <.001 | ||
| Unknown | 2175 | 1.19 (1.03-1.36) | .015 | ||
| 2-6 | 36 994 | - | - | ||
| ADT | Unknown | 2015 | 1.05 (0.90-1.23) | .535 | <.001 |
| Yes | 62 618 | 1.11 (1.06-1.17) | <.001 | ||
| No | 69 057 | - | - | ||
| Census median income quartiles 2008-2012 | ≥$63 000 | 45 839 | 0.90 (0.84-0.96) | <.001 | .004 |
| $48 000-$62 999 | 35 880 | 0.95 (0.89-1.02) | .147 | ||
| $38 000-$47 999 | 29 898 | 0.97 (0.91-1.04) | .359 | ||
| <$38 000 | 22 073 | - | - | ||
| Years of follow-up time | 5-9 | 57 562 | 1.32 (1.26-1.39) | <.001 | <.001 |
| 10+ | 27 912 | 1.38 (1.31-1.46) | <.001 | ||
| 2-4 | 48 216 | - | - | ||
| Primary payor | Medicare | 79 264 | 1.16 (1.07-1.26) | <.001 | <.001 |
| Private | 42 183 | 1.03 (0.94-1.11) | .559 | ||
| Other government/Not Insured/Unknown | 12 243 | - | - | ||
| Urban/Rural 2013 | Unknown | 2792 | 1.01 (0.87-1.18) | .854 | <.001 |
| Rural | 2296 | 1.35 (1.16-1.56) | <.001 | ||
| Urban | 17 844 | 1.06 (1.00-1.13) | .070 | ||
| Metro | 110 758 | - | - | ||
| Great circle distance (miles) | Intermediate | 41 844 | 0.84 (0.80-0.88) | <.001 | <.001 |
| Long | 7447 | 0.58 (0.51-0.65) | <.001 | ||
| Short | 84 399 | - | - | ||
| Age at diagnosis | 133 690 | 1.02 (1.02-1.02) | <.001 | <.001 | |
Abbreviations: CI, confidence interval; OR, odds ratio; SBRT, stereotactic body radiation therapy; IMRT, intensity-modulated radiation therapy; NH, Non-Hispanic. Bold values represent statistical significance with p<0.05.
*Number of observations in the original data set = 133 898. Number of observations used = 133 690.
**Backward selection with an alpha level of removal of 0.05 was used. The following variables were removed from the model: percent no high school degree 2008-2012, PSA, and chemotherapy.