Noninvasive detection of any-stage cancer using free glycosaminoglycans.

Cancer mortality is exacerbated by late-stage diagnosis. Liquid biopsies based on genomic biomarkers can noninvasively diagnose cancers. However, validation studies have reported ~10% sensitivity to detect stage I cancer in a screening population and specific types, such as brain or genitourinary tumors, remain undetectable. We investigated urine and plasma free glycosaminoglycan profiles (GAGomes) as tumor metabolism biomarkers for multi-cancer early detection (MCED) of 14 cancer types using 2,064 samples from 1,260 cancer or healthy subjects. We observed widespread cancer-specific changes in biofluidic GAGomes recapitulated in an in vivo cancer progression model. We developed three machine learning models based on urine (Nurine = 220 cancer vs. 360 healthy) and plasma (Nplasma = 517 vs. 425) GAGomes that can detect any cancer with an area under the receiver operating characteristic curve of 0.83-0.93 with up to 62% sensitivity to stage I disease at 95% specificity. Undetected patients had a 39 to 50% lower risk of death. GAGomes predicted the putative cancer location with 89% accuracy. In a validation study on a screening-like population requiring ≥ 99% specificity, combined GAGomes predicted any cancer type with poor prognosis within 18 months with 43% sensitivity (21% in stage I; N = 121 and 49 cases). Overall, GAGomes appeared to be powerful MCED metabolic biomarkers, potentially doubling the number of stage I cancers detectable using genomic biomarkers.

Variability of mpMRI diagnostic performance according to the upfront individual patient risk of having clinically significant prostate cancer.

BACKGROUND: To assess the variation of multiparametric magnetic resonance imaging (mpMRI) positive predictive value (PPV) according to each patient's risk of clinically significant prostate cancer (csPCa) based exclusively on clinical factors. METHODS: We evaluated 999 patients with positive mpMRI (PI-RADS ≥ 3) receiving targeted (TBx) plus systematic prostate biopsy. We built a multivariable logistic regression analysis (MVA) using clinical risk factors to calculate the individual patients' risk of harboring csPCa at TBx. A second MVA tested the association between individual patients' clinical risk and mpMRI PPV accounting for the PI-RADS score. Finally, we plotted the PPV of each PI-RADS score by the individual patient pretest probability of csPCa using a LOWESS approach. RESULTS: Overall, TBx found csPCa in 21%, 51%, and 80% of patients with PI-RADS 3, 4, and 5 lesions, respectively. At MVA, age, PSA, digital rectal examination (DRE), and prostate volume were significantly associated with the risk of csPCa at biopsy. DRE yielded the highest odds ratio (OR: 2.88; p < 0.001). The individual patient's clinical risk was significantly associated with mpMRI PPV (OR: 2.49; p < 0.001) using MVA. Plotting the mpMRI PPV according to the predicted clinical risks, we observed that for patients with clinical risk close to 0 versus patients with risk higher than 90%, the mpMRI PPV of PI-RADS 3, 4, and 5 ranged from 0% to 75%, from 0% to 96%, and from 45% to 100%, respectively. CONCLUSION: mpMRI PPV varies according to the individual pretest patient's risk based on clinical factors. These findings should be considered in the decision-making process for patients with suspect MRI findings referred for a prostate biopsy. Moreover, our data support the need for further studies to create an individualized risk prediction tool.

Use of 18F-fluoro-2-deoxy-d-glucose (18F-FDG) PET/CT for lymph node assessment before radical cystectomy in bladder cancer patients.

OBJECTIVE: To assess the diagnostic performance of 18F-fluoro-2-deoxy-d-glucose (18F-FDG) positron emission tomograpy (PET)/computed tomography (CT) in nodal staging before radical cystectomy (RC) and pelvic lymph node dissection (PLND) for bladder cancer (BCa). MATERIALS AND METHODS: This analysis was based on a cohort of 199 BCa patients undergoing RC and bilateral PLND between 2015 and 2022. Neoadjuvant chemotherapy (NAC) or immunotherapy (NAI) was administered after oncological evaluation. All patients received preoperative 18F-FDG PET/CT to assess extravesical disease. Point estimates for true negative, false negative, false positive, true positive, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of conventional imaging and PET/CT were calculated. Subgroup analysis in patients receiving neoadjuvant treatment was performed. RESULTS: At preoperative evaluation, 30 patients (15.1%) had 48 suspicious nodal spots on 18F-FDG PET/CT. At RC and bilateral PLND, a total of 4871 lymph nodes (LNs) were removed with 237 node metastases corresponding to 126 different regions. Pathological node metastases were found in 17/30 (57%) vs 39/169 patients (23%) with suspicious vs negative preoperative 18F-FDG PET/CT, respectively (sensitivity = 0.30, specificity = 0.91, PPV = 0.57, NPV = 0.77, accuracy = 0.74). On per-region analysis including 1367 nodal regions, LN involvement was found in 19/48 (39%) vs 105/1319 (8%) suspicious vs negative regions at PET/CT, respectively (sensitivity = 0.15, specificity = 0.98, PPV = 0.40, NPV = 0.92, ACC = 0.90). Similar results were observed for patients receiving NAC (n = 44, 32.1%) and NAI (n = 93, 67.9% [per-patient: sensitivity = 0.36, specificity = 0.91, PPV = 0.59, NPV = 0.80, accuracy = 0.77; per-region: sensitivity = 0.12, specificity = 0.98, PPV = 0.32, NPV = 0.93, ACC = 0.91]). Study limitations include its retrospective design and limited patient numbers. CONCLUSIONS: In eight out of 10 patients with negative preoperative 18F-FDG PET/CT, pN0 disease was confirmed at final pathology. No differences were found based on NAC vs NAI treatment. These findings suggest that 18F-FDG PET/CT could play a role in the preoperative evaluation of nodal metastases in BCa patients, although its cost-effectiveness is uncertain.

Robotic-assisted radical cystectomy with cutaneous ureterostomies: a contemporary multicenter analysis.

BACKGROUND: Robotic-assisted radical cystectomy (RARC) offers decreased blood loss during surgery, shorter hospital length of stay, and lower risk for thromboembolic events without hindering oncological outcomes. Cutaneous ureterostomies (UCS) are a seldom utilized diversion that can be a suitable alternative for a selected group of patients with competing co-morbidities and limited life expectancy. OBJECTIVE: To describe operative and perioperative characteristics as well as oncological outcomes for patients that underwent RARC + UCS. METHODS: Patients that underwent RARC + UCS during 2013-2023 in 3 centers (EU = 2, US = 1) were identified in a prospectively maintained database. Baseline characteristics, pathological, and oncological outcomes were analyzed. Descriptive statistics and survival analysis were performed using R language version 4.3.1. RESULTS: Sixty-nine patients were included. The median age was 77 years (IQR 70-80) and the median follow-up time was 11 months (IQR 4-20). Ten patients were ASA 4 (14.5%). Nine patients underwent palliative cystectomy (13%). The median operation time was 241 min (IQR 202-290), and the median hospital stay was 8 days (IQR 6-11). The 30-day complication rate was 55.1% (grade ≥ 3a was 14.4%), and the 30-day readmission rate was 17.4%. Eleven patients developed metastatic recurrence (15.9%), and 14 patients (20.2%) died during the follow-up period. Overall survival at 6, 12, and 24 months was 84%, 81%, and 73%, respectively. CONCLUSIONS: RARC + UCS may offer lower complication and readmission rates without the need to perform enteric anastomosis, it can be considered in a selected group of patients with competing co-morbidities, or limited life expectancy. Larger prospective studies are necessary to validate these results.

Oncological and perioperative outcomes of surgery with or without metastasis-directed therapy as part of a multimodal treatment in men with de-novo oligometastatic prostate cancer.

PURPOSE: To investigate the feasibility, safety, and oncological outcomes of Radical Prostatectomy (RP; either Robot-Assisted [RARP] or Open RP [ORP]) in oligometastatic prostate cancer (omPCa). Additionally, we assessed whether there was an added benefit of metastasis-directed therapy (MDT) in these patients in the adjuvant setting. METHODS: Overall, 68 patients with omPCa (≤ 5 skeletal lesions at conventional imaging) treated with RP and pelvic lymph node dissection between 2006 and 2022 were included. Additional therapies (androgen deprivation therapy [ADT] and MDT) were administered according to the treating physicians' judgment. MDT was defined as metastasis surgery/radiotherapy within 6 months of RP. We assessed Clinical Progression (CP), Biochemical Recurrence (BCR), post-operative complications and overall mortality (OM) of RP and the impact of adjuvant MDT + ADT versus RP + ADT alone. RESULTS: Median follow-up was 73 months (IQR 62-89). RARP reduced the risk of severe complications after adjusting for age and CCI (OR 0.15; p = 0.02). After RP, 68% patients were continent. Median 90-days PSA after RP was 0.12 ng/dL. CP and OM-free survival at 7 years were 50% and 79%, respectively. The 7-years OM-free survival rates were 93 vs. 75% for men treated with vs. without MDT (p = 0.04). At regression analyses, MDT after surgery was associated with a 70% decreased mortality rate (HR 0.27, p = 0.04). CONCLUSIONS: RP appeared to represent a safe and feasible option in omPCa. RARP reduced the risk of severe complications. Integrating MDT with surgery in the context of a multimodal treatment might improve survival in selected omPCa patients.

Predictive value of kallikrein forms and ß-microseminoprotein in blood from patients with evidence of detectable levels of PSA after radical prostatectomy.

PURPOSE: To determine whether ß-microseminoprotein or any of the kallikrein forms in blood-free, total or intact PSA or total hK2-predict metastasis in patients with evidence of detectable levels of PSA in blood after radical prostatectomy. METHOD: We determined marker concentrations in blood from 173 men treated with radical prostatectomy and evidence of detectable levels of PSA in the blood (PSA ≥ 0.05) after surgery between 2014 and 2015 and at least 1 year after any adjuvant therapy. We used Cox regression to determine whether any marker was associated with metastasis using both univariate and multivariable models that included standard clinical predictors. RESULTS: Overall, 42 patients had metastasis, with a median follow-up of 67 months among patients without an event. The levels of intact and free PSA and free-to-total PSA ratio were significantly associated with metastasis. Discrimination was highest for free PSA (c-index: 0.645) and free-to-total PSA ratio (0.625). Only free-to-total PSA ratio remained associated with overall metastasis (either regional or distant) after including standard clinical predictors (p = 0.025) and increased discrimination from 0.686 to 0.697. Similar results were found using distant metastasis as an outcome (p = 0.011; c-index increased from 0.658 to 0.723). CONCLUSION: Our results provide evidence that free-to-total PSA ratio can risk stratifying patients with evidence of detectable levels of PSA in blood after RP. Further research is warranted on the biology of prostate cancer markers in patients with evidence of detectable levels of PSA in blood after radical prostatectomy. Our findings on the free-to-total ratio for predicting adverse oncologic outcomes need to be validated in other cohorts.

Impact of prostate MRI central review over the diagnostic performance of MRI-targeted biopsy: should we routinely ask for an expert second opinion?

PURPOSE: There is substantial variability in multiparametric MRI (mpMRI) protocols and inter-readers' agreement. We tested the effect of a central mpMRI review on the detection of clinically significant PCa (csPCa) in a tertiary referral center. METHODS: We retrospectively analyzed a cohort of 364 consecutive men with a positive externally performed mpMRI (PI-RADS ≥ 3) who underwent a targeted biopsy (TBx) plus a systematic biopsy at a single tertiary referral center (2018-2020). Of those mpMRIs, 32% (n = 116) were centrally reviewed. We compared the detection of csPCa between the non-central-reviewed vs reviewed group. Multivariable logistic regression models (MVA) tested the relationship between mpMRI central review and the detection of csPCa at TBx. RESULTS: The detection of csPCa at TBx in non-central-reviewed vs central-reviewed group was 41 vs 63%, respectively (p = 0.001). The distribution of PI-RADS 2, 3, 4, and 5 at initial assessment vs after mpMRI central review was 0, 37, 47, and 16% vs 39, 9, 35, and 16%, respectively (p < 0.004). Of 43 patients with initial PI-RADS 3 score, respectively 67, 21, and 12, and 0% had a revised PI-RADS score of ≤ 2, 3, 4, and 5. At MVA, mpMRI central review (OR: 1.65, CI 0.85-0.98) was significantly associated with higher csPCa detection at TBx. CONCLUSIONS: We demonstrated that a central review of external mpMRIs may decrease the overcall of equivocal lesions, namely PI-RADS 3, and should be considered to maximize the clinical benefit of TBx in terms of increasing the detection of csPCa and eventually decreasing the rate of unnecessary biopsies.

Meningitis-retention syndrome: a review and update of an unrecognized clinical condition.

OBJECTIVES: We summarized the clinical and radiological characteristics of meningitis-retention syndrome (MRS), its therapeutic options, and urological outcome, to better understand the pathogenesis of this syndrome and to evaluate the effectiveness of corticosteroids in reducing the period of urinary retention. METHODS: We reported a new case of MRS in a male adolescent. We also reviewed the previously 28 reported cases of MRS, collected from inception up to September 2022. RESULTS: MRS is characterized by aseptic meningitis and urinary retention. The mean length of the interval between the onset of the neurological signs and the urinary retention was 6.4 days. In most cases, no pathogens were isolated in cerebrospinal fluid, except for 6 cases in which Herpesviruses were detected. The urodynamic study resulted in a detrusor underactivity, with a mean period for urination recovery of 4.5 weeks, regardless of therapies. DISCUSSION: Neurophysiological studies and electromyographic examination are not pathological, distinguishing MRS from polyneuropathies. Although there are no encephalitic symptoms or signs, and the magnetic resonance is often normal, MRS may represent a mild form of acute disseminated encephalomyelitis, without radiological detectable medullary involvement, due to the prompt use of steroids. It is believed that MRS is a self-limited disease, and no evidence suggests the effectiveness of steroids, antibiotics, and antiviral treatment in its clinical course.

Does previous prostate surgery affect multiparametric magnetic resonance imaging accuracy in detecting clinically significant prostate cancer? Results from a single institution series.

BACKGROUND: Multiparametric MRI (mpMRI) has demonstrated high diagnostic accuracy for clinically significant PCa (csPCa). However, the accuracy of this test in men that received a previous prostatic surgery is still controversial. We aimed at assessing the effect of previous prostatic surgery on the detection of csPCa in a tertiary referral center. METHOD: We relied on a cohort of 311 men with a positive mpMRI (prostate imaging - reporting and data system [PI-RADS] ≥ 3) who underwent a targeted (TBx) plus concomitant systematic random biopsy (SBx) at a single tertiary referral center between 2017 and 2020. The study outcome was to compare the detection of csPCa (Gleason score ≥ 3 + 4) between the two groups (no previous prostate surgery [Group 1] vs. previous prostate surgery [Group 2]). Multivariable logistic regression analysis (MVA) was used to assess the relationship between previous prostate surgery and the detection of csPCa at TBx, after taking into account potential clinical confounders. RESULTS: Overall, 24 (8%) patients received a previous prostate surgery before undergoing mpMRI. Median prostate-specific antigen density was 0.15 versus 0.08 ng/ml/cc, in Group 1 versus 2, respectively. The most frequent finding at mpMRI was in Group 1 versus 2, PI-RADS 4 (55%) versus PI-RADS 3 and 4 (42% each). The majority of patients were biopsy naïve in both Groups 1 (66%) and 2 (71%). The overall detection of csPCa in Group 1 versus 2 was 83% versus 75%, respectively. Differently, the detection of csPCa at TBx in Groups 1 versus 2 was 76% versus 71%, respectively. At MVA, previous prostate surgery (odds ratio: 0.65; p = 0.02) was significantly associated with lower csPCa detection at TBx, after accounting for potential confounders. CONCLUSION: The presence of previous prostate surgery significantly decreases the accuracy of mpMRI in detecting csPCa. These results should be taken into account when assessing patients with a history of prostatic surgery and a suspicious lesion at mpMRI, to better select those who might avoid an unnecessary biopsy.

Multiparametric magnetic resonance imaging of the prostate underestimates tumour volume of small visible lesions.

OBJECTIVE: To assess the relationship between the volume of the index lesion (IL) measured at multiparametric magnetic resonance imaging (mpMRI; MRIvol) and at radical prostatectomy (RPvol), stratifying it according to Prostate Imaging-Reporting and Data System (PI-RADS) score. PATIENTS AND METHODS: We identified 332 men with a positive mpMRI (single lesion with PI-RADS ≥3) who underwent systematic plus targeted biopsy and subsequent RP at two tertiary referral centres between 2013 and 2018. All mpMRIs were reviewed by experienced radiologists using PI-RADS scores. The study outcome was to assess the relationship between MRIvol (based on planimetry from MRI sequence best showing tumour) and RPvol (based on tumour involved area of each RP pathology slice). To achieve this endpoint, we performed a multivariable linear regression analysis (LRA) to predict RPvol using PI-RADS, prostate-specific antigen level, prostate volume, age, digital rectal examination, Gleason score at MRI-targeted biopsy, biopsy history and time from mpMRI to RP as covariates. Non-parametric locally estimated scatterplot smoothing (LOESS) function was used to graphically explore the relationship between MRIvol and RPvol, stratifying for PI-RADS score. RESULTS: Overall, 24%, 49% and 27% of men had visible PI-RADS 3, 4 and 5 lesions at mpMRI. The median (interquartile range [IQR]) MRIvol and RPvol were 0.67 (0.29-1.76) mL and 1.39 (0.58-4.23) mL. At LRA, MRIvol was significantly correlated with a RPvol underestimation (slope: 2.4, 95% confidence interval [CI] 0.1-46.3). The non-parametric LOESS analysis showed a non-linear relationship between MRIvol and RPvol. Significant underestimation was reported across all volumes with the highest differences between MRIvol and RPvol in the low volume range (<2 mL), where RPvol almost doubled MRIvol. A similar effect was observed across all PI-RADS scores subgroups. CONCLUSIONS: In the present study, mpMRI significantly underestimated the exact volume of the IL, especially for small visible lesions, regardless of PI-RADS score. This should be considered when planning tailored focal therapy approaches often delivered to men with smaller prostatic lesions.

Multicentre study revealed significant gaps between evidence-based recommendations for using corticosteroids for croup and clinical practice.

AIM: Adherence to croup management recommendations has been poorly investigated. This study aimed to describe the treatment patterns in two paediatric emergency departments and analyse the adherence to recommendations. METHODS: We conducted a retrospective chart review of children diagnosed with croup in two Italian paediatric emergency departments in 2017. Data on clinical presentation, corticosteroid administration and home therapy were collected. Length of stay, hospitalisation and re-access rates were compared among different corticosteroid treatment groups. RESULTS: We enrolled 632 patients (61.1% males) with a mean age of 42.8 ± 55.1 months. Corticosteroids were administered to 403 (63.8%) children in the emergency departments. Dexamethasone was administered to 1 (0.4%) patient. Inhaled and oral corticosteroids were given to 342 (54.1%) and 226 (35.8%) patients, respectively. Home therapy was prescribed for 603 (95.4%) patients, either with inhaled (86.2%) and/or oral (43.8%) corticosteroids. The re-access rate was 2.8%. The actual pharmaceutical costs were an estimated 10 times higher than they would have been if the recommendations had been followed. CONCLUSION: A significant gap between the evidence and clinical practice for croup treatment was observed. Improving adherence to the recommendations could lead to clinical and economic benefits.

Association between Lesion Location and Oncologic Outcomes after Focal Therapy for Localized Prostate Cancer Using Either High Intensity Focused Ultrasound or Cryotherapy.

PURPOSE: We assessed whether prostate cancer (PCa) location might affect oncologic outcomes after focal therapy (FT) for PCa. MATERIALS AND METHODS: We identified 274 men receiving FT for PCa using either high intensity focused ultrasound (HIFU) or cryotherapy at a high volume center between 2009 and 2018. Survival analyses using Kaplan-Meier method were used to assess any additional treatment and radical treatment rates according to PCa location. Propensity-score match analysis was used to compare oncologic outcomes of HIFU vs cryotherapy according to PCa location. Covariates were prostate specific antigen, clinical stage, prostate volume, Gleason score, maximum cancer core length, percentage of positive cores and treatment modality. RESULTS: A total of 166 and 108 men received FT with HIFU and cryotherapy, respectively. Overall, 39% (106) and 31% (85) received at least an additional treatment and a radical treatment after FT, respectively, with a median followup of 51 months. At 36 months' followup, the rates of any additional treatment-free survival were 71%, 75%, and 69% for patients with basal, mid-prostate and apical disease, respectively (p=0.7). At multivariable logistic regression analysis, PCa location was not significantly associated with higher risk of either any additional treatment or radical treatment (all p >0.4). After matching, there was no difference between HIFU vs cryotherapy in terms of any additional treatment rates according to PCa location. CONCLUSIONS: The PCa location does not significantly affect the rate of failure after FT. The presence of an apical lesion should not be considered an exclusion criteria for FT. Both HIFU and cryotherapy likely achieve similar medium-term oncologic results regardless of PCa location.

Neoadjuvant and adjuvant immunotherapy in renal cell carcinoma.

OBJECTIVE: The treatment landscape for renal cell carcinoma (RCC) is rapidly evolving. The aim of this review is to summarize the randomized-controlled trials evaluating the role of immunotherapy in neoadjuvant or adjuvant setting. MATERIALS AND METHODS: We searched PubMed, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov for studies including neoadjuvant or adjuvant immunotherapy, and provided a brief overview of the pharmacodynamics of immunotherapy for RCC. RESULTS: Several drugs are currently under investigation. In the neoadjuvant setting, four studies are evaluating the role of single-agent immunotherapy, one of dual-agent immunotherapy, and four studies the role of immunotherapy in combination with tyrosine kinase inhibitors or anti-interleukin-1 beta. In the adjuvant setting, two studies are evaluating the role of single-agent immunotherapy and two of dual-agent immunotherapy. CONCLUSIONS: The approval of immune checkpoint inhibition as a front-line therapeutic strategy for advanced RCC has also ultimately led to the investigation of these agents first in the adjuvant and then in the neoadjuvant setting. Currently, there are nine studies aimed to evaluate the role of immunotherapy in the neoadjuvant setting and four studies in the adjuvant setting.

Visible Light Mediated Photocatalytic N-Radical Cascade Reactivity of γ,δ-Unsaturated N-Arylsulfonylhydrazones: A General Approach to Structurally Diverse Tetrahydropyridazines.

Tetrahydropyridazines are of particular interest for their versatility as intermediates in organic synthesis and display pharmacological activity in several domains. Here, we describe the photocatalytic synthesis of different tetrahydropyridazines starting from γ,δ-unsaturated N-arylsulfonylhydrazones. Simple structural changes of substrates result into three different pathways beginning from a common N-hydrazonyl radical, which evolves through a domino carboamination/dearomatization, a HAT process, or a photoinduced radical Smiles rearrangement to afford diverse tetrahydropyridazines. All reactions are carried out in very mild conditions, and the quite inexpensive [Ru(bpy)3]Cl2 is used as the catalyst. Preliminary mechanism studies are presented, among them luminescence and electrochemical characterization of the involved species. Computational studies allow to rationalize the mechanism in accord with the experimental findings.

Design, Characterization and Applications of Functional Nanomaterials.

Nanomaterials are commonly defined as particles existing in nature or artificially manufactured materials that have one or more external dimensions in the 1-100 nm range [...].

Evaluation of the Photocatalytic Activity of a Cordierite-Honeycomb-Supported TiO2 Film with a Liquid-Solid Photoreactor.

Anatase nanoparticles in suspension have demonstrated high photoactivity that can be exploited for pollutant removal in water phases. The main drawback of this system is the difficulty of recovering (and eventually reusing) the nanoparticles after their use, and the possible interference of inorganic salts (e.g., sulfates) that can reduce the performance of the photocatalyst. The present work describes the development of a cordierite-honeycomb-supported TiO2 film to eliminate the problems of catalyst recovery. The catalyst was then tested against phenol in the presence of increasing concentrations of sulfates in a specially developed recirculating modular photoreactor, able to accommodate the supported catalyst and scalable for application at industrial level. The effect of SO42- was evaluated at different concentrations, showing a slight deactivation only at very high sulfate concentration (≥3 g L-1). Lastly, in the framework of the EU project Project Ô, the catalyst was tested in the treatment of real wastewater from a textile company containing a relevant concentration of sulfates, highlighting the stability of the photocatalyst.

On the Simple Complexity of Carbon Monoxide on Oxide Surfaces: Facet-Specific Donation and Backdonation Effects Revealed on TiO2 Anatase Nanoparticles.

Atomic-scale relationships between the structure of TiO2 surfaces and the physicochemical properties of surface sites, functional for titania-based applications, can be obtained from IR spectroscopy by using carbon monoxide (CO) as a molecular probe. In the literature, it is reported that strongly unsaturated cationic Ti sites (Lewis acid), which are important for reactivity, should cause a large upshift of the CO stretching frequency. By using IR spectroscopy of CO on TiO2 nanomaterials and theoretical analyses, here this model is challenged. It is shown that the stretching frequency of adsorbed CO results from a facet-dependent and synergic CO-surface donation (upshift) - surface-CO backdonation (downshift) mechanism. These results imply that the interaction of adsorbed molecules with the Ti centers is tuned by the surface oxygen atoms of the first coordination sphere, which play an active role as indirect electron density donors (Lewis base).