## 3 Results  
### Patients Characteristics  
A total of 56 patients were first screened for this proof of concept study. Thirteen patients were excluded due to lack of quality or quantity of their tumor tissue from the TURBT, so 43 patients were finally included in the analysis. Patients, tumor, and treatment characteristics are presented in Tables 1 and 2. The mean age at diagnosis was 66 years, and 77% of patients were male. Smoking concerned 85% of the patients' cohort. All patients had \(\geq\) pT2 disease before NAC. The mean number of chemotherapy cycles was 4 and the mean period between last chemotherapy and curative surgery was 40 days. Discontinuation of treatment is not reported due to missing data. The mean follow-up was 22 months (6-54). Among 19 (44%) responder patients, 14 (74%) had complete pathological response (pT0) and 26% had incomplete response (\(\leq\)pT2 but >pT0).  
\begin{table}
\begin{tabular}{l c} \hline \hline
**Patients Characteristics at Diagnosis** & **Mean (Lower Quartile–Upper Quartile)** \\ \hline Age & 66 (48–78) \\ \hline Sex & \\ Male & 33 (77\%) \\ Female & 10 (23\%) \\ \hline OMS & \\
0 & 17 (39\%) \\
1 & 16 (37\%) \\
2 & 3 (8\%) \\ Missing data & 7 (16\%) \\ \hline Charlson score & 3 (2–6) \\ \hline Smokers & 34 (85\%) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Patients characteristics.  
\begin{table}
\begin{tabular}{l c} \hline \hline
**Treatment and Tumor Characteristics** & **Number \%** \\ \hline Tumor response & \\ Responders & 19 (44\%) \\ Non responders & 24 (56\%) \\ \hline Chemotherapy & \\ MVAC-I & 10 (24\%) \\ G gemcitabine cisplatin & 24 (57\%) \\ Gematibn carboplatin & 8 (19\%) \\ \hline Mean number of chemotherapy cycles & 4 (3–6) \\ \hline Toxicities (any grade) & 19 (44\%) \\ \hline Time between last chemotherapy and surgery & 40 (7–69) \\ (days) & \\ \hline Relapse & \\ Number & 11 (34\%) \\ Distance surgery-relapse (months) & 15 (2–37) \\ Metastatic & 10 (91\%) \\ Missing data & 11 (26\%) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Tumor and treatment characteristics.  
IR Analysis of the Transurethral Resection of Bladder Tumor Samples and Constitution of Calibration and External Validation Sets  
FTIR imaging was carried out on all samples, one by one, and provided 2,789,796 spectra containing potentially valuable information on the intrinsic molecular composition of TURBT tissues. Data were first pre-processed by using EMSC to neutralize undesirable interferences and normalize data according to a target spectrum (mean spectrum of the dataset). Then, to build the predictive PLS-DA (Partial Least Square--Discriminant Analysis) and PLS (Partial Least Square) models and to estimate their performances, the samples were divided into two data sets: calibration set and external validation set. For mimicking a clinical application of our approach, data of each patient (i.e., all images corresponding to the same patient) were allocated either to calibration set or to test set. Thus, 79 images corresponding to 43 patients were separated into two data sets: 42 images in calibration (22 patients) and 37 images in external validation (21 patients). Responder and non-responder patients were divided equitably among the calibration and test sets to maintain homogeneity of the groups.