Diffusion-weighted magnetic resonance imaging for predicting pathologic response to neoadjuvant chemoradiotherapy in esophageal squamous cell cancer.

Abstract

e15510 Background: Neoadjuvant chemoradiotherapy(nCRT) followed by surgery has became the standard treatment for patients with locally advanced esophageal cancer. However, cumulating data showed that only patients who had a pathologic response to neoadjuvant treatment could benefit from the nCRT and surgery. Moreover, for patients with no pathologic response, nCRT even worsen the survival compared with surgery alone. Therefore, accurately differentiating the two groups was contributed to personalize treatment for esophageal cancer. Our study aimed to explore the potential value of diffusion-weighted magnetic resonance imaging (DWI-MRI) for the prediction of pathologic response to nCRT in esophageal squamous cell carcinoma. Methods: Nineteen patients underwent DWI-MRI within one week before and after nCRT. Tumor regression score (TRG) was assessed by two experienced pathologists after esophagetcomy. The average tumor apparent diffusion coefficient (ADC) of tumor was calculated before and after neoadjuvant treatment. The predictive potential of pre-nCRT ADC (ADCpre), post-nCRT ADC (ADCpost) and ADC change (ΔADC) for pathologic responders (TRG≥3) and good responders (pCR and near-pCR, TRG1-2) was assessed. Results: Among these patients, 12 patients showed a positive response, and 8 patients showed a good response to nCRT. The ADCpre values in responders were significantly higher than these in no-responders (2.31±0.53×10-3mm2/s vs. 1.72±0.40 mm2/s, P= 0.021). According to ROC analysis for ADCpre, an optimal cut-off value of 1.77×10-3mm2/s predicted the responders with a sensitivity of 83.33 %, specificity of 71.43 %, PPV of 83.33 %, NPV of 71.43 %. The ADCpost values in good responders were significantly higher than these in poor responders (3.44±0.62×10-3 mm2/s vs. 2.73±0.31 mm2/s, P= 0.004). The ADCpost was predictive of the good responders at a threshold of 3.21×10-3mm2/s (sensitivity of 87.50 %, specificity of 100.00 %, PPV of 100.00 %, NPV of 91.67 % ). Conclusions: ADC value can be used as a promising biomarker to predict pathologic response of esophageal squamous cell carcinoma to neoadjuvant chemoradiotherapy.