Impact of ADC Value on Conversion Surgery for Unresectable Colorectal Liver Metastasis

Background/Aim: We examined the impact of apparent diffusion coefficients (ADC) calculated from diffusion-weighted-magnetic resonance imaging on prognostic prediction and establishment of a treatment strategy for conversion surgery in patients with initially unresectable colorectal liver metastasis (CRLM). Patients and Methods: Thirty patients underwent conversion surgery for initially unresectable CRLM. The minimum ADC was calculated after chemotherapy. Patients were divided into low ADC (n=6) and high ADC (n=24) groups, and clinicopathological factors were compared between the two groups. Results: The low ADC group had higher rates of male sex, large tumor diameter and high carbohydrate antigen 19-9 level (≥37 U/ml) than the high ADC group (p<0.05). In cancer-specific and disease-free survival analyses, the low ADC group showed a significantly worse prognosis than the high ADC group (p<0.01). Multivariate analysis identified a low ADC and chemotherapy regimen other than FOLFOXIRI as independent prognostic factors for poor cancer-specific survival (p<0.05). Conclusion: ADC values after chemotherapy can be used to estimate the prognosis after conversion hepatectomy for patients with initially unresectable CRLM. ADC values may therefore be helpful for selecting patients for conversion surgery after completing a FOLFOXIRI regimen.