Table 2. Propensity-matched comparative use of SBRT and PBT by baseline characteristics.
| Characteristic | Photon (n=56), n (%) | Proton (n=56), n (%) | OR | 95% CI | P |
|---|---|---|---|---|---|
| Sex | |||||
| Male | 41 (73.2) | 39 (69.6) | 1 | Ref | |
| Female | 15 (26.8) | 17 (30.4) | 0.84 | 0.37–1.91 | 0.68 |
| Race | |||||
| White | 53 (94.6) | 52 (92.9) | 1 | Ref | |
| African American | 0 (0.0) | 1 (1.8) | – | – | 0.99 |
| Other | 3 (5.4) | 3 (5.4) | 1.02 | 0.20–5.29 | 0.98 |
| Comorbidity score | |||||
| 0 | 23 (41.1) | 17 (30.4) | 1 | Ref | |
| 1 | 21 (37.5) | 23 (41.1) | 1.48 | 0.63–3.50 | 0.37 |
| ≥2 | 12 (21.4) | 16 (28.6) | 1.80 | 0.68–4.79 | 0.24 |
| Age, years | |||||
| ≤65 | 35 (62.5) | 35 (62.5) | 1 | Ref | |
| >65 | 21 (37.5) | 21 (37.5) | 0.79 | 0.36–1.75 | 0.79 |
| Insurance | |||||
| Private payer | 13 (23.2) | 10 (17.9) | 0.77 | 0.13–4.65 | 0.77 |
| Government/uninsured | 43 (76.8) | 44 (78.6) | 1.03 | 0.20–5.38 | 0.98 |
| Education | |||||
| ≥29% | 17 (30.9) | 27 (49.1) | 1 | Ref | |
| 20% to 28.9% | 15 (27.3) | 13 (23.6) | 0.55 | 0.21–1.42 | 0.22 |
| 14% to 19.9% | 12 (21.8) | 9 (16.4) | 0.47 | 0.16–1.36 | 0.16 |
| <14% | 11 (20.0) | 6 (10.9) | 0.34 | 0.11–1.10 | 0.07 |
| Facility type | |||||
| Non-academic/research program | 7 (12.5) | 3 (5.4) | 1 | Ref | |
| Academic/research program | 49 (87.5) | 53 (94.6) | 2.16 | 0.51–9.12 | 0.29 |
| Facility geographic location | |||||
| East | 6 (10.7) | 4 (7.1) | 1 | Ref | |
| Midwest | 3 (5.4) | 1 (1.8) | 0.5 | 0.04–6.68 | 0.60 |
| West | 47 (83.9) | 51 (91.1) | 1.63 | 0.43–6.13 | 0.47 |
| Patient residence | |||||
| Metro | 53 (94.6) | 56 (100.0) | 1 | Ref | |
| Urban/rural | 3 (5.4) | 0 (0.0) | – | – | 0.98 |
| Income, USD | |||||
| ≤48,000 | 26 (46.4) | 24 (42.9) | 1 | Ref | |
| >48,000 | 30 (53.6) | 32 (57.1) | 1.16 | 0.55–2.44 | 0.70 |
| Distant to facility, miles | |||||
| ≤20 | 22 (39.3) | 29 (51.8) | 1 | Ref | |
| >20 | 34 (60.7) | 27 (48.2) | 0.60 | 0.28–1.28 | 0.19 |
| T stage | |||||
| T1 | 39 (69.6) | 36 (64.3) | 1 | Ref | |
| T2 | 17 (30.4) | 20 (35.7) | 1.28 | 0.58–2.82 | 0.55 |
| Tumor size, cm | |||||
| ≤2 | 11 (19.6) | 9 (16.1) | 1 | Ref | |
| 2–5 | 37 (66.1) | 35 (62.5) | 1.16 | 0.43–3.13 | 0.78 |
| >5 | 8 (14.3) | 12 (21.4) | 1.83 | 0.52–4.44 | 0.34 |
| Biologic equivalent dose (Gy) | |||||
| <100 | 26 (47.3) | 27 (49.1) | 1 | Ref | |
| ≥100 | 29 (52.7) | 28 (50.9) | 0.93 | 0.44–1.96 | 0.85 |
| Year of diagnosis | |||||
| 2004–2007 | 5 (8.9) | 5 (8.9) | 1 | Ref | |
| 2008–2011 | 29 (51.8) | 23 (41.1) | 0.79 | 0.20–3.07 | 0.73 |
| 2012–2014 | 22 (39.3) | 28 (50.0) | 1.27 | 0.33–4.96 | 0.73 |
Please note that all numbers may not add up to the total number of cases due to missing data. T stage based upon AJCC TNM staging manual. SBRT, stereotactic body radiation therapy; PBT, proton beam therapy; Gy, Gray; USD, United States Dollar.