ABSTRACT
Objective:To explore the value of MRI high-resolution T2WI based-radiomics in predicting pathologic complete response (pCR) after neoadjuvant therapy for rectal cancer.Methods:This retrospective study included 80 patients with rectal cancer confirmed by postoperative pathology, who underwent high-resolution imaging of rectal MRI before neoadjuvant therapy from January 2018 to March 2019 in our hospital. After manually delineating the volume of interest (VOI) of the lesion in the high-resolution T2WI image, the radiomics features were extracted, and the least absolute shrinkage and selection operator (LASSO) algorithm was adopted to reduce the dimension and select the features that were valuable for tumor pCR. Using Random algorithm, the data were randomly divided into training set ( n=64) and test set ( n=16) for machine learning, and 4 kinds of machine learning models including decision tree (DT), logistic regression (LR), random forests (RF) and extreme gradient boosting (XGBoost) were established and ROC curves were drawn. The area under the curve (AUC), sensitivity, specificity and 95% CI were respectively calculated, and the difference of ROC curves was compared with DeLong test. Results:Among 80 patients with rectal cancer, there were 15 cases by pCR, accounting for 18.75%, and 65 cases were non-pCR, accounting for 81.25%. A total of 1 409 imaging features were extracted. After dimension reduction by LASSO algorithm, 8 most valuable features were selected. The AUC of DT, LR, RF and XGBoost in the test set group was 0.870, 0.801, 0.912, 0.945, the AUC of XGBoost was the largest, and the differences between XGBoost and DT, LR, RF were statistically significant ( P=0.008; P=0.006; P=0.009), and the pairwise comparisons of DT, LR, RF showed no statistically significant difference ( PLR-RF=0.083; PDT-LR=0.113; PDT-RF=0.879). The sensitivity was 78.57%, 64.29%, 78.57%, 85.71%, and the specificity was 95.38%, 84.62%, 92.31%, 98.46% respectively. The 95% CI was 0.775-0.935, 0.696-0.882, 0.827-0.964, 0.870-0.984. Conclusion:The radiomics based on high-resolution T2WI images has predictive value for pCR after neoadjuvant treatment of rectal cancer. XGBoost model has better predictive efficiency than DT, LR and RF, and can be used to guide clinical individualized treatment and related interventions.
ABSTRACT
Objective To investigated the influence of different combined treatment sequence of stereotactic body radiation therapy (SBRT) and chemotherapy (CT) on the survival of very elderly patients with locally advanced pancreatic cancer ( LAPC) .Methods The data of LAPC patients ≥60 years old treated by CyberKnife SBRT at Shanghai Changhai Hospital from January 2012 to December 2016 was retrospectively analyzed.According to treatment sequences , patients were divided into three groups:CT+SBRT group ( first chemotherapy and then SBRT ) , SBRT+CT group ( first SBRT and then chemotherapy ) and CT+SBRT+CT group ( first chemotherapy , then SBRT and finally chemotherapy ) .Patients were recommended to receive a 6-month chemotherapy .Intravenous administration of 1000 mg/m2 gemcitabine was initiated on day 1, 8, and 15 every 4 weeks or S-1 was orally given at a dose of 80 mg/m2 for 28 days followed by a 14-day rest , which repeated for 6 cycles.Radiotherapy parameters: the median total prescription dose was 36(30-45)Gy; the median per fraction dose was 7(5-9)Gy;the median number of fractions was 5(5-8) fractions;the median biological equivalent dose (BED10) were 61.92(48-85.5) Gy, respectively.The interval between SBRT and chemotherapy ranged from 2 to 3 weeks.Patients were followed every 3 months.The main outcome measures were overall survival ( OS) and median progression free survival ( PFS) .Second outcome measure was adverse events.Common Terminology Criteria for Adverse Events Version 4.0 (CTCAE 4.0) was employed to evaluate adverse events , and RTOG/EORTC was used to assess the adverse events of radiotherapy .Overall survival (OS) and PFS were calculated by Kaplan-Meier method.Univariate and multivariate logistic regression model were used to analyze the independent risk factors .Results A total of 260 patients were enrolled in the study , including 28 patients treated with CT+SBRT, 163 patients undergoing SBRT +CT and 69 patients treated with CT+SBRT+CT.The median OS and PFS were 13.2(95％CI 12.8-13.6)months and 8.2(95％CI 7.7-8.7)months, respectively.OS in CT +SBRT, SBRT +CT and CT +SBRT +CT group was 12.2 (10.9-13.9),13.4 ( 12.9-13.9 ) and 13.1 ( 12.7-13.5 ) months, and the differences were not statistically significant(P=0.425).PFS in CT+SBRT, SBRT+CT and CT+SBRT+CT group was 6.4(5.9-6.9), 8.3(7.8-8.8) and 8.2(7.2-9.2)months, and the differences were statistically significant (P=0.008).In univariate analysis , ECOG, SIRI, the extent of decreased CA 19-9 after treatment and BED 10 were important factors of OS.In multivariate analysis, the CA19-9 response and BED10 were independent factors for OS . Multivariate analysis showed that the extent of decreased CA 19-9 after treatment and BED 10 were important factors of OS.In CT+SBRT group, patients had lower ECOG score (χ2 =115.325,P<0.001) and earlier clinical staging (χ2 =24.788, P<0.001 ).In SBRT +CT group, patients had advanced staging (χ2 =159.759,P<0.001) and lymph node metastasis(χ2 =40.925,P<0.001).Only 1 patient experienced grade 3 radiotherapy associated duodenitis .The adverse events of patients who were first treated by chemotherapy included grade 3 neutropenia in 4 patients and grade 3 gastrointestinal reaction in 5 patients.The adverse events of patients who were first treated by radiotherapy included grade 3 neutropenia or/and leucopenia in 18 patients and grade 3 abdominal pain, nausea or vomit in 16 patients.The adverse events of CT +SBRT+CT patients included grade 3 neutropenia or/and leucopenia in 4 patients and grade 3 abdominal pain or nausea in 5 patients.There was no grade ≥4 adverse events.Conclusions For very elderly patients with LAPC , the survival of patients who received pre-SBRT chemotherapy , post-SBRT chemotherapy and pre-and post-SBRT chemotherapy was comparable , but SBRT+CT group and CT +SBRT+CT group had longer PFS than CT +SBRT group.