Predicting Response to Total Neoadjuvant Treatment (TNT) in Locally Advanced Rectal Cancer Based on Multiparametric Magnetic Resonance Imaging: A Retrospective Study

Abstract

Purpose

To investigate the potential value of magnetic resonance imaging (MRI) in predicting response relevance to total neoadjuvant treatment (TNT) in locally advanced rectal cancer.

Methods

We analyzed MRI of 71 patients underwent TNT from 2015 to 2017 retrospectively. We categorized the response of TNT as CR (complete response) vs non-CR, and high vs moderate vs low sensitivity. Logistic regression analysis was used to identify the best predictors of response. Diagnostic performance was assessed using receiver operating characteristic curve analysis.

Results

Post-ICT (induction chemotherapy) ∆TL (tumor length), post-CRT (concurrent chemoradiotherapy) ∆LNN (the numbers of lymph node metastases), post-CCT (consolidation chemotherapy) ∆S_DWI (maximum cross-sectional area of tumor on diffusion-weighted imaging), post-CCT ADC_T (the mean apparent diffusion coefficient values of tumor) and post-CCT ∆LNV (volume of lymph node) were the best CR predictors. Post-ICT ∆TL, post-CRT EMVI (extramural vascular invasion) and post-CCT ∆S_T2 (S on T2-weight) were the best significant factors for high sensitivity.

Conclusion

Post-ICT ∆TL may be an early predictor of CR and high sensitivity to TNT. Dynamic analysis based on MRI between baseline and post-CCT could provide the most valuable prediction of CR. The grouping modality of CR vs non-CR may be more suitable for treatment response prediction than high vs moderate vs low sensitivity.

Keywords:

• rectal cancer
• total neoadjuvant treatment
• MRI
• response
• TRG

Acknowledgments

Supported by grants from the National Natural Science Foundation of China (82073338), grants from Science and Technology bureau of Chengdu of China (2019-YF05-00771-SN), grants from the 1·3·5 Project for Disciplines of Excellence – Clinical Research Incubation Project, West China Hospital, Sichuan University (2020HXFH002).

Ethical Approval

This is a retrospective study. And the study was approved by the Ethics Committee on Biomedical Research, West China Hospital of Sichuan University (2020-903). Patient consent was not required. The reasons for the waiver were as follows. Firstly, this is a retrospective study. There was no additional risk to patients. In the process of ethical approval, we have submitted to the ethics committee the application for exemption from informed consent of patients. Additionally, we abided by the Declaration of Helsinki. We collected de-identified data of patients. And the final results of the study would be anonymity.

Disclosure

The authors report no conflicts of interest in this work.