Table 3.
Sensitivity of Quantitative Methylated BCAT1/IKZF1 ctDNA and CEA for Recurrence According to Cancer Features and Treatment
| Test Sensitivity for Recurrence, n/N (%) | P | ||
|---|---|---|---|
| ctDNA | CEA | ||
| Stage at primary diagnosis | |||
| I | N/A | N/A | N/A |
| II | 9/13 (69.2) | 4/13 (30.8) | .0499 |
| III | 21/30 (70.0) | 11/29 (37.9) | .013 |
| IV | 3/7 (42.9) | 0/5 (0) | .310 |
| Treatment of primary tumor | |||
| Resection ± adjuvant therapy | 25/41 (61.0) | 12/38 (31.6) | .009 |
| Neoadjuvant therapy only (low rectal cancers) | 8/9 (88.9) | 3/9 (33.3) | .016 |
| Nature of recurrence | |||
| Locoregional | 10/13 (76.9) | 2/13 (15.4) | .006 |
| Distant | 23/37 (62.1) | 13/34 (38.2) | .044 |
| Treatment of recurrence | |||
| Treatment with curative intent | 12/20 (60.0) | 4/20 (20.0) | .010 |
Abbreviations: BCAT1, branched‐chain amino acid transaminase 1; CEA, carcinoembryonic antigen; ctDNA, circulating tumor DNA; IKZF1, Ikaros family zinc‐finger 1 protein; N/A, not applicable.