Table 4.
Univariable and multivariable logistic regression model to identify covariates associated with late CTCAE gastrointestinal toxicity after SBRT.
| Covariates | Level | CTCAE Grade 2+ GI Late Toxicity (6–24 Months) | CTCAE Grade 2+ GI Persistent GI Late Toxicity | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No (n = 357) |
Yes (n = 51) |
Univariable | Multivariable (n = 413) |
No (n = 392) |
Yes (n = 22) |
Univariable | |||||
| N (%) or Median (IQR) |
N (%) or Median (IQR) |
OR (95% CI) |
p value |
OR (95% CI) |
p value |
N (%) or Median (IQR) |
N (%) or Median (IQR) |
OR (95% CI) |
p value |
||
| Baseline grade 2+ GI toxicity |
No Yes Missing |
357 (99) 4 (1) 2 |
51 (100) 0 0 |
386 (99) 4 (1) 2 |
22 (100) 0 0 |
||||||
| Baseline EPIC-26 bowel sub-domain score |
Median (n) |
100 (92-100) (n=318) |
96 (88-100) (n=46) |
0.96 (93-0.99) | 0.004 | 100 (92-100) (n=344) |
96 (86-100) (n=20) |
0.95 (0.92-0.99) | 0.007 | ||
| Worst acute grade 2+ GI Toxicity |
No Yes |
316 (87) 47 (13) |
33 (65) 18 (35) |
3.67 (1.91-7.03) | <0.0001 | 3.68 (1.89-7.17) | <0.0001 | 336 (86) 56 (14) |
13 (59) 9 (41) |
4.15 (1.70-10.17) | 0.002 |
| Persistent grade 2+ acute GI toxicity |
No Yes |
353 (97) 10 (3) |
47 (92) 4 (8) |
3.00 (0.91-9.96) | 0.07 | 381 (97) 11 (3) |
19 (86) 3 (14) |
5.47 (1.41-21.24) | 0.014 | ||
| Worst acute EPIC-26 bowel sub-domain score |
Median (n) |
88 (75-96) (n=351) |
79 (63-94) (n=48) |
0.99 (0.97-1.00) | 0.04 | 88 (75-96) (n=378) |
75 (63-88) (n=21) |
0.98 (0.96-0.99) | 0.01 | ||
| Worst acute bowel symptoms Grade 1+ rectal bleeding Grade 2+ diarrhoea Grade 1+ rectal pain Grade 2+ proctitis |
No Yes No Yes No Yes No Yes |
277 (76) 85 (24) 342 (95) 20 (5) 277 (77) 85 (23) 346 (95) 17 (5) |
32 (63) 19 (37) 43 (84) 8 (16) 24 (47) 27 (53) 45 (88) 6 (12) |
1.93 (1.04-3.59) 3.18 (1.32-7.66) 3.67 (2.01-6.69) 2.71 (1.02-7.24) |
0.04 0.01 <0.0001 0.05 |
297 (76) 94 (24) 367 (94) 24 (6) 290 (74) 101 (26) 373 (95) 19 (5) |
12 (55) 10 (45) 18 (82) 4 (18) 11 (50) 11 (50) 18 (82) 4 (18) |
2.63 (1.10-6.29) 3.40 (1.07-10.83) 2.87 (1.20-6.83) 4.36 (1.34-14.16) |
0.03 0.04 0.02 0.014 |
||
| Age | Median (n) |
69 (65-73) (n=363) |
68 (64-73) (n=51) |
0.99 (0.95-1.04) | 0.70 |
69 (65-73) (n=392) |
71 (65-74) (n=22) |
1.02 (0.96-1.10) | 0.46 | ||
| Prostate Volume (cm3) |
Median (n) |
40 (31-56) (n=359) |
39.5 (33-57) (n=50) |
1.00 (0.99-1.02) | 0.53 | 40 (31-56) (n=388) |
39 (32-58) |
1.01 (0.99-1.03) | 0.56 | ||
| Risk group (intermediate) |
low Int |
28 (8) 335 (92) |
7 (14) 44 (86) |
0.53 (0.22-1.27) | 0.15 | 0.45 (0.17-1.18) | 0.19 | 33 (8) 359 (92) |
2 (9) 20 (91) |
0.92 (0.21-4.11) | 0.91 |
| SBRT modality (CL) | CK CL Other/ missing |
155 (43) 206 (57) 2 |
14 (27) 35 (69) 2 |
1.88 (0.98-3.61) | 0.06 | 1.67 (0.77-3.60) | 0.19 | 167 (43) 223 (57) 2 |
2 (9) 18 (82) 2 |
6.74 (1.54-29.45) | 0.01 |
| Fiducial use (Yes) | No Yes |
93 (26) 270 (74) |
18 (35) 33 (65) |
0.63 (0.34-1.17) | 0.15 | 0.73 (0.35-1.54) | 0.41 | 102 (26) 290 (74) |
9 (41) 13 (59) |
0.51 (0.21-1.22) | 0.13 |
OR = odds ratio; IQR = interquartile range; CL = conventional linac; GI = gastrointestinal; EPIC = Expanded Prostate Cancer Index Composite; CK = Cyberknife; Int = Intermediate. Multivariable analysis for CTCAE grade 2+ persistent late GI toxicity was noted performed due to low number of events.