Prognostic value of diffusion-weighted imaging to cytoreductive surgery with or without hyperthermic intraperitoneal chemotherapy for patients with gastric cancer and peritoneal metastases

Background To investigate the prognostic value of the apparent diffusion coefficient (ADC) calculated from diffusion-weighted imaging (DWI) to cytoreductive surgery (CRS), with or without hyperthermic intraperitoneal chemotherapy (HIPEC), for gastric cancer (GC) patients with peritoneal metastasis (PM). Methods Between May 2016 and December 2020, 95 newly diagnosed GC patients with PM who underwent CRS combined with HIPEC (CRS + HIPEC group, n = 61) and CRS alone (CRS group, n = 34) were retrospectively included. All patients underwent abdominal 3.0 T MRI scan, including DWI, and the mean ADC (ADC(mean)), minimum ADC (ADC(min)), and maximum ADC (ADC(max)) values of the whole-volume tumor were measured. The prognostic value of the ADC parameters and clinical and histopathological characteristics were investigated by univariate and multivariate Cox analyses. Results The median overall survival (OS) periods of the CRS + HIPEC and CRS groups were 18 and 9 months, respectively ([hazard ratio (HR) = 0.44 [95% CI: 0.27-0.71], P<0.001). The ADC(mean) and ADC(min) values were positively correlated with OS in all patients (Spearman's rho [R] = 0.361 and 0.470), as well as in the CRS + HIPEC (R = 0.369 and 0.417) and CRS (R = 0.192 and 0.409) groups. The multivariate Cox analysis demonstrated that the ADC(mean) <= 1.39 x 10(- 3) mm(2)/s and ADC(min) <= 0.77 x 10(- 3) mm(2)/s were significantly associated with a negative prognosis in the total population (HR = 1.68 [95% CI: 1.02-2.75] and 2.48 [95% CI: 1.51-4.08], P all < 0.05) and the CRS + HIPEC group (HR = 2.22 [95% CI: 1.19-4.14] and 2.37 [95% CI: 1.26-4.37], P all < 0.05), along with pathologic T and N stages. Only the ADC(min) <= 0.77 x 10(- 3) mm(2)/s was identified as an independent prognostic factor in the CRS group (HR = 3.49 [95% CI: 1.19-10.20], P = 0.022). Conclusions The minimum ADC was identified as a strong independent prognostic factor for GC patients with PM who underwent CRS, with or without HIPEC.