Relationship between apparent diffusion coefficient values and clinicopathologic features in rectal cancer: a cross-sectional study.

Abstract

Background: The prognosis of rectal cancer is closely related to its clinicopathologic features. Accurate preoperative assessment of these features is crucial for treatment planning and prognosis prediction. The apparent diffusion coefficient (ADC), derived from diffusion-weighted imaging (DWI), has shown potential as a noninvasive imaging biomarker for evaluating tumor characteristics. This study aimed to explore the relationship between ADC values and the clinicopathological features of rectal cancer.

Methods: We retrospectively recruited 97 eligible patients with rectal adenocarcinoma who underwent magnetic resonance imaging (MRI) and surgical resection at our institution between January 2023 and December 2023. Each patient was evaluated for the presence of extramural vascular invasion (EMVI) or circumferential resection margin (CRM) on MRI, and the mean (ADC_mean), minimum (ADC_min), and maximum (ADC_max) ADC values were calculated. Moreover, the relationship between the ADC values and clinicopathological features, including tumor stage, histologic grade, lymphovascular invasion, perineural invasion, and lymph node metastasis, were statistically analyzed.

Results: Among 97 patients with rectal cancer, the mean age was 61.40±10.46 years and 60 (61.9%) were males. ADC_mean, ADC_min, and ADC_max were significantly lower in patients with EMVI or CRM than in those without EMVI or CRM (P<0.05). Pathologic T1-2 staging exhibited higher ADC_mean (0.79±0.26 vs. 0.61±0.22, P=0.001), ADC_min (0.71±0.26 vs. 0.55±0.22, P=0.002) and ADC_max (0.89±0.26 vs. 0.75±0.22, P=0.004) compared with T3-4 staging. Highly and moderately differentiated tumors had higher ADC_mean, ADC_min, and ADC_max than less-differentiated tumors (P<0.05). Patients with lymphovascular invasion, perineural invasion, and lymph node metastasis showed significantly lower ADC_mean, ADC_min, and ADC_max than those without these conditions (P<0.05). ADC_mean, ADC_min and ADC_max were negatively correlated with EMVI (r=-0.334, -0.340, -0.302), CRM (r=-0.362, -0.414, -0.276), pathologic T-stage (r=-0.324, -0.313, -0.276), histologic grade (r=-0.353, -0.352, -0.289), lymphovascular invasion (r=-0.405, -0.384, -0.421), perineural invasion (r=-0.428, -0.407, -0.265), and lymph node metastasis (r=-0.347, -0.316, -0.268) in rectal cancer.

Conclusions: ADC values were negatively associated with different clinicopathological features of rectal cancer, suggesting their potential role as noninvasive imaging markers for preoperative tumor assessment.