Table 1.
Patient and Tumor Characteristics Among 62 Patients With MMR-Deficient Rectal Cancer
| Characteristic | No. of Patients (%) |
|---|---|
| Age at rectal cancer diagnosis, median (IQR), years | 41 (35-54) |
| Sex | |
| Male | 32 (52) |
| Female | 30 (48) |
| Race/ethnicity | |
| White | 51 (82) |
| Black | 3 (5) |
| Hispanic | 4 (6.5) |
| Asian | 4 (6.5) |
| Rectal cancer presentation | |
| Rectal cancer as index cancer | 58 (93.5) |
| Synchronous high-risk colon lesion | 12 (19.4) |
| Prior colon cancer | 4 (6.4) |
| Tumor distance from anal verge, median (IQR), cm | 7.5 (4.6-12) |
| Tumor histologic grade | |
| Well differentiated | 2 (3.2) |
| Moderately differentiated | 53 (85.5) |
| Poorly differentiated | 7 (11.3) |
| Mucinous tumor | 38 (61.3) |
| Tumor-infiltrating lymphocytes | 3 (4.8) |
| Clinical stage of rectal cancer at diagnosis | |
| cT1-T2N0 | 17 (27.4) |
| cT3-4N0 | 14 (22.5) |
| cTanyN-positive | 26 (41.9) |
| cTanyNanyM-positive | 5 |
| Surgical procedure* | 59 |
| Segmental | 41 (69.5) |
| Low anterior resection | 25 |
| Coloanal anastomosis | 5 |
| Abdominal perineal resection/partial or total pelvic exenteration | 11 |
| Extended | 11 (18.6) |
| Near-TPC, ileo–low rectal anastomosis | 4 |
| TPC, IPAA | 2 |
| TPC, end ileostomy | 5 |
| Local excision | 7 (11.9) |
| Neoadjuvant therapy (fluorouracil and long-course radiation) | 30 (75% of 40 patients with cT3 to 4 or cN-positive) |
Abbreviations: IPAA, ileal pouch anal anastomosis; IQR, interquartile range; MMR, mismatch repair; TPC, total proctocolectomy.
*
Three patients declined surgical resection because of: complete clinical response to neoadjuvant therapy (one), metastatic progression (one), and concurrent lymphoma (one).