Prognostic utility of diffusion-weighted MRI in oesophageal cancer; is apparent diffusion coefficient a potential marker of tumour aggressiveness?

Purpose To investigate the role of the apparent diffusion coefficient (ADC) as a potential prognostic biomarker in the evaluation of the aggressiveness of oesophageal cancer. Materials and methods Between November 2009 and December 2013, 43 patients with evidence of oesophageal or oesophago-gastric junction cancer were referred to our institution and prospectively entered in our database. The final study population consisted of 23 patients (18 men; 5 women; mean age, 64.62 ± 10.91 years) who underwent diffusion-weighted Magnetic Resonance before surgical intervention. Specifically, 14 were directly treated with surgery and 9 were addressed to chemo/radiotherapy beforehand. Two radiologists independently measured mean tumour ADC and inter-observer agreement (Spearman’s and intraclass correlation coefficient [ICC]) was assessed. In the univariate analysis, overall survival curves related to pathological ADC, pT, pN, tumour location and histotype were fitted using the Kaplan–Meier method. Survival curves were then compared using the log-rank test. Results Inter-observer reproducibility was very good (Spearman’s rho = 0.95; ICC = 0.94). At a total median follow-up of 19 months (2–49 months), 4 patients had died. The median follow-up was 18.50 months (5–49 months) for the surgery-only group (1/4 events, 25 %) and 24 months (2–34 months) for the chemo/radiotherapy group (3/4 events, 75 %). Survival time at 48 months for the overall population was 59 % (±0.11), while for the surgery-only group and the chemo/radiotherapy group was 90 % (±0.09) and 61 % (±0.34), respectively. In the univariate analysis, ADC values below or equal to 1.4 × 10−3 mm2/s were associated with a negative prognosis both in the total population (P = 0.016) and in the surgery-only group (P < 0.001).