Colorectal cancer liver metastases: Apparent diffusion coefficient for prediction of histopathologic response grade after neoadjuvant systemic chemotherapy

Zielsetzung Histopathologic tumor regression grade (TRG) after neoadjuvant systemic chemotherapy (NACT) is an independent predictor of local recurrence and overall survival in patients with colorectal liver metastases. Aim of this study was to correlate the post-NACT, pre-surgical ADC of colorectal cancer liver metastases with histopathologic TRG after liver resection.

Material und Methoden A total 17 patients (9 male, 8 female) with 33 colorectal cancer liver metastases receiving NACT containing irinotecan, oxaliplatin, or both, were included in this analysis. After completion of NACT and within 2 weeks prior to surgical resection of liver metastases, patients underwent DW-MRI at 1.5T with b-values: 0, 50, 800 s/mm2. Minimal ADC was measured for each metastasis by manually rendering a volume of interest. Metastases on MR imaging were carefully correlated with metastases identified at pathological analysis of the resected liver specimen in order to correlate individual metastatic ADC-with histological TRG according to Rubbia-Brandt.

Ergebnisse At histopathology, tumor regression was graded as TRG -1 in 3, TRG-2 in 3, TRG-3 in 7, TRG-4 in 13, and TRG-5 in 7 metastases. Mean ADC (in 10-3mm2/s) in the respective groups was TRG-1: ADC 1.2 ± 0.26, TRG 2: 1.3 ± 0.31, TRG 3:1.2± 0.46, TRG 4: 0.68 ± 0.32, and TRG 5: 0.76 ± 0.25. Thus, post-NACT ADC and TRG at histology correlated moderately (r=-0.38, p=0.031).

Schlußfolgerungen ADC of colorectal liver metastases after NACT correlates with their degree of regression at histopathology.