Prognostic Value of Diffusion MR Imaging and Clinical-Pathologic Factors in Patients with Rectal Cancer

[Background]Apparent diffusion coefficient (ADC) value measured from diffusion-weighted magnetic resonance (MR) images are highly correlated with pathological T or N stage, tumor differentiation grade, and extramural depth of tumor in patients with rectal cancer.[Objectives]To assess the prognostic value of diffusion MR imaging and clinical-pathologic risk factors in patients with rectal cancer.[Patients and Methods]This retrospective study was approved by our institutional review board and written informed consent was waived. Sixty-one consecutive patients with rectal cancer (41 men and 20 women; mean age, 64.5 ± 12.1 years; range, 32 - 86 years) underwent pelvic MR imaging. Tumor ADC value and clinical-pathologic risk factors were tested as possible risk factors for postoperative local recurrence or distant metastasis (LRDM) as well as disease-free survival outcome.[Results]Of 62 tumors, 12 (19.4%) had postoperative LRDM (median follow-up 38.5 months). Plasmatic CA19-9 level (P = 0.0027), pathological N stage (P = 0.0018), lymphatic invasion (P < 0.0001), and tumor ADC value (P = 0.0076) were independently associated with postoperative LDRM. High plasmatic CA19-9 level (≥ 37 U/mL) (P = 0.010), ly2 (P = 0.020), ly3 (P < 0.0001), pathological N2 (P = 0.006), and low tumor ADC value (< 0.996 × 10^-3 mm²/sec) (P = 0.0026) were associated with reduced disease-free survival.[Conclusion]Preoperative tumor ADC and plasmatic CA19-9 were significantly associated with postoperative LRDM and disease-free survival in rectal cancer.