Table 2.
Comparative use of conventional radiation therapy (XRT) versus IMRT by baseline characteristics in patients receiving treatment for rectal cancer
| Characteristic | Conventional XRT (n = 18,359) | IMRT (n = 3,131) | OR | 95% CI | p-value |
|---|---|---|---|---|---|
| Sex | |||||
| Male | 11,507 (63) | 1,960 (63) | 1 | Ref | |
| Female | 6,852 (37) | 1,171 (37) | 1.00 | 0.93–1.09 | 0.93 |
| Race | |||||
| Caucasian | 15,990 (87) | 2,752 (88) | 1 | Ref | |
| African-American | 1,389 (8) | 224 (7) | 0.94 | 0.81–1.09 | 0.39 |
| Other | 980 (5) | 155 (5) | 0.92 | 0.77–1.09 | 0.34 |
| Comorbidity score | |||||
| 0 | 14,615 (80) | 2,448 (78) | 1 | Ref | |
| 1 | 3,048 (17) | 533 (17) | 1.04 | 0.94–1.16 | 0.41 |
| ≥2 | 696 (3) | 150 (5) | 1.29 | 1.07–1.54 | 0.0065* |
| Age (yr) | |||||
| ≤60 | 9,609 (52) | 1,600 (51) | 1 | Ref | |
| >60 | 8,750 (48) | 1,531 (49) | 1.05 | 0.97–1.13 | 0.2 |
| Insurance | |||||
| None | 857 (5) | 162 (5) | 1 | Ref | |
| Private payer | 9,569 (53) | 1,582 (51) | 0.87 | 0.73–1.04 | 0.13 |
| Government | 7,718 (42) | 1,351 (44) | 0.92 | 0.77–1.11 | 0.40 |
| Education (%) | |||||
| ≥29 | 2,890 (16) | 414 (13) | 1 | Ref | |
| 20–28.9 | 4,837 (27) | 798 (26) | 1.15 | 1.01–1.31 | 0.0298* |
| 14–19.9 | 6,089 (33) | 1,127 (36) | 1.29 | 1.14–1.46 | <0.0001* |
| <14 | 4,421 (24) | 777 (25) | 1.23 | 1.08–1.39 | 0.0018* |
| Facility type | |||||
| Community cancer program | 1,506 (9) | 219 (7) | 1 | Ref | |
| Comprehensive cancer program | 7,788 (45) | 1,364 (46) | 1.2 | 1.03–1.40 | 0.0172* |
| Academic/research program | 8,185 (46) | 1,403 (47) | 1.18 | 1.01–1.37 | 0.0347* |
| Facility location | |||||
| Metro | 14.302 (80) | 2,473 (81) | 1 | Ref | |
| Urban | 3,127 (17) | 518 (17) | 0.96 | 0.86–1.06 | 0.41 |
| Rural | 484 (3) | 67 (2) | 0.80 | 0.62–1.04 | 0.09 |
| Income (USD) | |||||
| <30,000 | 3,101 (17) | 472 (15) | 1 | Ref | |
| 30,000–35,000 | 4,493 (25) | 793 (25) | 1.16 | 1.03–1.31 | 0.0181* |
| 35,000–45,999 | 5,037 (28) | 917 (29) | 1.20 | 1.06–1.35 | 0.0034* |
| >46,000 | 5,592 (30) | 932 (31) | 1.10 | 0.97–1.23 | 0.14 |
| T stage | |||||
| T1 | 110 (1) | 21 (1) | 1 | Ref | |
| T2 | 852 (5) | 155 (5) | 0.95 | 0.58–1.57 | 0.85 |
| T3 | 15,747 (87) | 2,601 (84) | 0.87 | 0.54–1.38 | 0.54 |
| T4 | 1,327 (7) | 308 (10) | 1.22 | 0.75–1.97 | 0.43 |
| N stage | |||||
| N0 | 8,494 (47) | 1,333 (43) | 1 | Ref | |
| N1 | 8,079 (45) | 1,460 (47) | 1.15 | 1.06–1.25 | 0.0006* |
| N2 | 1,321 (8) | 290 (10) | 1.40 | 1.22–1.61 | <0.0001* |
| Distance to facility (miles) | |||||
| ≤11 | 9,098 (50) | 1,594 (49) | 1 | Ref | |
| >11 | 9,261 (50) | 1,537 (51) | 0.94 | 0.88–1.02 | 0.16 |
| Grade | |||||
| Well differentiated | 1,278 (8) | 208 (8) | 1 | Ref | |
| Moderately differentiated | 12,533 (78) | 2,119 (79) | 1.04 | 0.89–1.21 | 0.63 |
| Poorly differentiated | 2,178 (14) | 359 (13) | 1.01 | 0.84–1.22 | 0.89 |
| Year of diagnosis | |||||
| 2004–2006 | 3,315 (18) | 96 (3) | 1 | Ref | |
| 2007–2009 | 4,743 (26) | 537 (17) | 3.91 | 3.13–4.88 | <0.0001* |
| 2010–2012 | 5,893 (32) | 1,260 (40) | 7.38 | 5.97–9.13 | <0.0001* |
| 2013–2015 | 4,408 (24) | 1,238 (40) | 9.7 | 7.84–11.99 | <0.0001* |
Values are presented as number (%).
IMRT, intensity-modulated radiation therapy; OR, odds ratio; CI, confidence interval.
*
p < 0.05.