B-374 Early Prediction of Recurrent Non-muscle Invasive Bladder Cancer Using ATR-FTIR in Urine Samples
Authors: Kalil H , Maher S , Mohamed A , El-Tobgy A , Bayachou M , El-Falouji A 
Published: September 2023

Abstract

Background
Non-Muscle Invasive Bladder Cancer (NMIBC) represents approximately 80% of all cases of bladder cancer. It consists primarily of low-grade tumors but has been associated with a high recurrence rate. The high recurrence rate is a significant challenge in its management and treatment plan. Recurrence can occur within months of initial treatment and can lead to more invasive treatment, including surgery combined with additional rounds of chemotherapy. Although the 5-year relative survival rate for patients with NMIBC is around 90%, the risk of recurrence is also high, with up to 70% of patients experiencing a recurrence within 5 years of initial treatment. For this reason, ongoing surveillance and monitoring are critical for people with NMIBC. Invasive cystoscopy, the current standard of care for NMIBC diagnosis and surveillance, can be uncomfortable and painful and carry the risk of complications such as bleeding, infection, and bladder perforation. The development of a fast and non-invasive biopsy-based assay would significantly improve the management of NMIBC. A liquid biopsy-based assay would provide a less invasive alternative that could be used to monitor the disease and detect recurrence while reducing the need for invasive cystoscopy.

Methods
A fast liquid biopsy-based assay is used with urine samples to enhance the detection of cancer-specific biomarkers. Here, we describe a fast spectroscopic approach for detecting NMIBC recurrence in urine samples. Before the cystoscopy examination, urine samples from 62 previously diagnosed NMIBC patients were collected at their follow-up appointments. Fourier transforms infrared (ATR-FTIR) spectra were acquired from urine samples using the direct application. Utilizing parameter grid searching, spectral processing, and normalization were enhanced. Multivariate and principal component analyses (PCA) were employed to examine the technical variability.

Results
Cystoscopy outcomes of 62 NMIBC patients (41 cancer-free, 21 recurrences) were documented and used as a reference to our non-invasive approach. We examined the performance of 35 machine learning models using a training set (70%) and a held-out test set (30%). A Regularized Random Forests (RRF) model attained an AUROC of 0.92 with a sensitivity of 86% and a specificity of 77%. The variable importance and predictive ROC spikes around 2912 cm−1 have confirmed the peak of lipid CH2 asymmetrical stretching. An additional spike is also observed around 2980 cm−1, reflecting the stretching vibrations of methyl hydrocarbon chains. Analyzing processed spectra clearly reveals spectral differences between recurrence and NMIBC-free samples. Together, our results suggest an altered lipid profile in urine samples of the recurrent NMIBC patients.

Conclusion
To the best of our knowledge, this is the first study showing the CH2 lipid asymmetrical fingerprint on the FTIR spectra in the range of 2800 to 3000 cm−1, indicating the recurrence of NMIBC. Because of this explicit fingerprint, this liquid-biopsy spectroscopic technique can offer a promising non-invasive diagnostic tool for the early detection of recurrent NMIBC.