The value of apparent diffusion coefficient in predicting treatment response of rectal cancer after neoadjuvant radiation therapy

Tóm tắt

Objective: To evaluate the value of the apparent diffusion coefficient (ADC) in predicting treatment response in rectal cancer patients after neoadjuvant chemoradiation therapy (nRCT). Subject and method: A study was conducted on 29 rectal cancer patients who underwent nRCT. Patients underwent magnetic resonance imaging (MRI), and tumor volume and ADC values (b-values: 0-1000s/mm²) were measured before and after nRCT. ADC values were measured in two ways: 1. For the entire tumor (ADC₁) and 2. On the slice with the largest tumor area (ADC₂). Changes in tumor volume (ΔV) and ADC values (ΔADC) before and after treatment were compared with the surgical pathology results, categorized into complete response (pCR)/incomplete response and downstaging T/not downstaging T groups. Result: ΔADC values were higher in the downstaging T group compared to the non-downstaging T group, with ΔADC₁ values of 45.4% and 19.1%, respectively (p = 0.005), and ΔADC₂ values of 51.7% and 20.2%, respectively (p = 0.01). At the ΔADC₁ threshold of 42.2%, sensitivity was 55.6%, and specificity was 100%, while for ΔADC₂ at 18.1%, sensitivity and specificity were 88.9% and 72.7%, respectively. There was no statistically significant difference in ΔADC values between the complete response and incomplete response groups (p>0.05). Changes in tumor volume did not provide prognostic value for treatment response to NRCT. Conclusion: The ΔADC value is a potential prognostic factor in predicting treatment response in rectal cancer patients after nRCT, with more accurate diagnostic information compared to tumor volume.