Table 2.
Patient demographics and response based on ctDNA pre- and post-TNT.a
| Characteristic | Pre-TNT ctDNA (n = 22) | Post-TNT ctDNA (n = 44) | ||||
|---|---|---|---|---|---|---|
| Positive (n = 18) | Negative (n = 4) | P-value | Positive (n = 4) | Negative (n = 40) | P-value | |
| Age on study, median (range) | 57 (43-76) | 59 (49-72) | 1.00 | 61 (57-80) | 55 (32-76) | 1.00 |
| Sex, female, no. (%) | 6 (33) | 2 (50) | .60 | 2 (50) | 16 (40) | 1.00 |
| Performance status, no. (%) | ||||||
| 0 | 14 (78) | 3 (75) | 1.00 | 1 (25) | 34 (85) | .02 |
| 1 | 4 (22) | 1 (25) | 3 (75) | 6 (15) | ||
| Race, no. (%) | ||||||
| Caucasian | 13 (72) | 4 (100) | 1.00 | 4 (100) | 30 (75) | 1.00 |
| African American | 2 (11) | 0 (0) | 0 (0) | 4 (10) | ||
| Other | 3 (17) | 0 (0) | 0 (0) | 6 (15) | ||
| Regimen, no. (%) | ||||||
| SCRT + chemotherapy | 17 (94) | 4 (100) | 1.00 | 1 (25) | 37 (8) | .33 |
| LCRT + chemotherapy | 1 (6) | 0 (0) | 3 (75) | 3 (92) | ||
| Distance from anal verge, no. (%) | ||||||
| High (10.1-15 cm) | 4 (22) | 0 (0) | .80 | 1 (25) | 9 (23) | .81 |
| Mid (5.1-10 cm) | 6 (33) | 2 (50) | 2 (50) | 18 (45) | ||
| Lower (0-5 cm) | 8 (44) | 2 (50) | 1 (25) | 13 (33) | ||
| cT stage, no. (%) | ||||||
| 1-2 | 1 (6) | 1 (25) | .34 | 0 (0) | 7 (18) | 1.00 |
| 3-4 | 17 (94) | 3 (75) | 4 (100) | 33 (82) | ||
| cN stage, no. (%) | ||||||
| 0-1 | 13 (72) | 2 (50) | .56 | 3 (75) | 26 (65) | 1.00 |
| >2 | 5 (28) | 2 (50) | 1 (25) | 14 (35) | ||
| mrTRG response, no. (%) | ||||||
| TRG1-2 | 9 (50) | 4 (100) | .12 | 1 (25) | 24 (60) | .30 |
| TRG3-5 | 9 (50) | 0 (0) | 3 (75) | 16 (40) | ||
| Endoscopic response | ||||||
| Overall, no. | 16 | 4 | 2 | 39 | ||
| cCR, no. (%) | 8 (50) | 3 (75) | .59 | 1 (50) | 21 (54) | 1.00 |
| Residual disease, no. (%) | 8 (50) | 1 (25) | 1 (50) | 18 (46) | ||
| Pathologic response | ||||||
| Overall, no. | 9 | 0 | 3 | 19 | ||
| pCR, no. (%) | 2 (22) | 0 (N/A) | N/A | 0 (0) | 9 (47) | .24 |
| Residual disease, no. (%) | 7 (78) | 0 (N/A) | 3 (100) | 10 (53) | ||
aSelect percentages may not add up to 100 due to rounding.
Abbreviations: TNT, total neoadjuvant therapy; SCRT, short-course radiotherapy; LCRT, long-course radiotherapy; cT, clinical tumor stage; cN, clinical lymph node stage; mrTRG, magnetic resonance tumor regression grade.