Extent of enhancement on multiphase contrast-enhanced CT images is a potential prognostic factor of stage I-III colon cancer

By evaluating extent of tumour enhancement on preoperative contrast-enhanced MDCT, we aimed to establish an imaging-based model to predict cancer-specific survival in stage I-III colon cancer. A total of 548 stage I-III colon cancer patients who underwent curative resection from 2007 to 2013 were retrospectively included and divided into primary cohort and validation cohort according to admission time. The attenuation coefficient of each colon cancer was measured on the workstation by drawing the ROI in CT images. The enhancement ratio was calculated using maximum tumour attenuation value in triphasic MDCT scanning divided by the minimum. Patients were divided into low/high-enhancement groups according to the optimal cut-off value derived from time-dependent ROC curve. Kaplan-Meier method and COX regression analysis were adopted to evaluate prognostic value of variables. A nomogram for prognosis was conducted on the basis of a multivariate Cox proportional hazard model. No significant differences were observed in age, sex, pTNM stage, perioperative chemoradiotherapy, serum CEA, tumour size, tumour localisation and histologic type between low- and high-enhancement groups. The high-enhancement group had a significantly shorter cancer-specific survival rate (69.5%) than the low-enhancement group (85.9%) (p $<$ 0.001). Subgroup analysis indicated that high-enhancement state was closely associated with increased risk of colon cancer mortality in stage I (p = 0.033), stage II (p = 0.002) and stage III (p = 0.014). Cox regression analysis indicated the extent of enhancement was an independent prognostic factor (HR 2.258, 95% CI 1.476-3.455; p $<$ 0.001). The extent of tumour enhancement on MDCT can serve as a potential risk factor for stage I-III colon cancer. (orig.)