Effectiveness of rectal MRI and endorectal ultrasound predicting the complete response of rectal cancer after neoadjuvant chemoradiotherapy / 中国实用外科杂志

ABSTRACT

OBJECTIVE: To offer some important insights into clinical decision-making by evaluating endorectal ultrasound and rectal MRI when they were used to predict pathological complete response for rectal cancer patients who were performed neoadjuvant therapy. METHODS: The study was a prospective cohort study which was conducted at a single tertiary care center. Patients diagnosed with mid-low rectal cancer between May 2014 and June 2018 in Peking Union Medical College Hospital were collected in the study. Both of their endorectal ultrasound and rectal MRI were performed to evaluate the tumor stage before their preoperative chemoradiation and were reevaluated at the 6 to 7 th weeks after their preoperative radiation treatment. The pathological preoperative tumor staging achieved by endorectal ultrasound and rectal MRI was compared with postoperative staging by pathologic examination. Sensitivity,specificity,accuracy and Youden index of each evaluation method and their combination were calculated. The ROC curve was administered likewise. RESULTS: A total of 247 patients were enrolled in the study. The sensitivity,specificity,accuracy,positive predictive value,negative predictive value and Youden index for ypT0 N0 separate evaluation of for whom was qualified as compete endorectal ultrasound(163 patients) and of rectal MRI(212 patients) was15.9% and 23.1%,94.0% and 94.9%,77.8% and 83.4%,0.1 and 0.2. Combined two methods,the data were recorded as 13.6%,98.1%,83.6% and 0.1.Area under curve ROC for ultrasound and MRI when using specifically for ypT0 N0 measurement was 0.656 and 0.742.The two modalities showed 0.517 and 0.667 in terms of AUC when comparing with each other. CONCLUSION: The sensitivity of MRI and ERUS as terms of diagnosing complete response is rather unsatisfactory,although they all bear a relatively good specificity. For the patients not diagnosed with clinical response by one of the two methods,radical operations were strongly recommended. For the patients confirmed as complete response by both modalities,there still exists possibilities that residual tumor persists,“watch and wait”approach can be taken cautiously and the patient must be followed up intensely.