Prognostic Role of Diffusion-weighted MR Imaging for Resectable Gastric Cancer.

To prospectively investigate the role of apparent diffusion coefficient (ADC) calculated from diffusion-weighted magnetic resonance (MR) imaging as a potential prognostic biomarker in the evaluation of the aggressiveness of gastric cancer. This prospective study had institutional review board approval. Informed consent was obtained from all patients. Between October 2009 and December 2013, a total of 99 patients (65 men, 34 women; mean age, 62.02 years; age range, 32.33-85.15 years) with biopsy-proved cancer (28 esophagogastric junction and 71 gastric cancers) were examined with a 1.5-T MR imaging system, including T1-, T2-, and diffusion-weighted sequences. ADC measurements were obtained. Seventy-one patients were directly treated with surgery, while 28 underwent neoadjuvant chemotherapy beforehand. Pathologic ADC, pathologic T and N stages, tumor location, surgical approach, and histologic subtype were investigated with univariate and multivariate analyses by using the Cox regression model. At a total median follow-up period of 21 months, 31 patients had died. The median follow-up was 25 months for the surgery-only group (19 of 31 events [61%]) and 28 months for the chemotherapy group (12 of 31 events [39%]). In the multivariate analysis, ADC values of 1.5 × 10(-3) mm(2)/sec or lower were associated with a negative prognosis, both in the total population (log-relative risk, 1.73; standard error, 0.56; P = .002) and in the surgery-only (log-relative risk, 1.97; standard error, 0.66; P = .003) and chemotherapy (log-relative risk, 2.93; standard error, 1.41; P = .03) groups, along with other significant prognostic factors (in particular, pathologic T and N stages). Pathologic ADC represents a strong independent prognostic factor in the evaluation of the aggressiveness of gastric cancer, in addition to clinical and surgical variables.