Identification of CT-based non-invasive radiomic biomarkers for overall survival prediction in oral cavity squamous cell carcinoma

This study addresses the limited non-invasive tools for Oral Cavity Squamous Cell Carcinoma (OSCC) survival prediction by identifying Computed Tomography (CT)-based biomarkers to improve prognosis prediction. A retrospective analysis was conducted on data from 149 OSCC patients, including CT radiomics and clinical information. An ensemble approach involving correlation analysis, score screening, and the Sparse-L1 algorithm was used to select functional features, which were then used to build Cox Proportional Hazards models (CPH). Our CPH achieved a 0.70 concordance index in testing. The model identified two CT-based radiomics features, Gradient-Neighboring-Gray-Tone-Difference-Matrix-Strength (GNS) and normalized-Wavelet-LLL-Gray-Level-Dependence-Matrix-Large-Dependence-High-Gray-Level-Emphasis (HLE), as well as stage and alcohol usage, as survival biomarkers. The GNS group with values above 14 showed a hazard ratio of 0.12 and a 3-year survival rate of about 90%. Conversely, the GNS group with values less than or equal to 14 had a 49% survival rate. For normalized HLE, the high-end group (HLE > - 0.415) had a hazard ratio of 2.41, resulting in a 3-year survival rate of 70%, while the low-end group (HLE ≤ - 0.415) had a 36% survival rate. These findings contribute to our knowledge of how radiomics can be used to predict the outcome so that treatment plans can be tailored for patients people with OSCC to improve their survival.

Positive Predictive Value of PET CT in HPV Associated Oropharyngeal Cancers Treated with Definitive Proton Therapy

PURPOSE/OBJECTIVE(S)

Proton therapy (PT) offers attractive dosimetric advantages but there is emerging literature suggesting relative biological effectiveness (RBE) differences at the distal end of the Bragg peak may result in increased posttreatment FDG avidity. While the utility of PET CT is well established, lingering posttreatment inflammation from PT may affect the interpretation of posttreatment scans (PTS). We seek to characterize the positive predictive value (PPV) and negative predictive value (NPV) for residual disease/locoregional recurrence in patients undergoing definitive PT with HPV associated oropharyngeal cancer.

MATERIALS/METHODS

We performed a single institution retrospective analysis of patients with HPV associated oropharyngeal cancer treated with PT between 2016-2022. Patients were included if they had both pretreatment and initial posttreatment restaging PET/CT available for analysis. SUVmax was recorded in both the primary tumor and involved lymph nodes. Patients were considered to have a positive PET CT if there was an SUV decrease of less than 65% from the baseline exam or if there was SUV > 4.0 based on thresholds defined by previous studies. Chi-square analysis was used to compare patients who had a positive PTS to those who did not.

RESULTS

Sixty-two patients were included for analysis with a median age of 62. The entire cohort had a median follow up of 21 months (Range 2-71 months) of whom 86% received chemotherapy. Eleven patients (17%) had PTS defined as positive, of whom only one (PPV 9%) was found to have residual/locoregionally recurrent disease within an area of FDG avidity on PTS. Another patient developed a new primary tumor 9 months later in an area outside of FDG avidity on PTS. The remainder were followed with serial clinical exam with or without the compliment of repeat imaging. They remained without evidence of residual/locoregionally recurrent disease at the time of last follow up. Fifty-one patients had negative posttreatment scans, with only one patient having residual/locoregionally recurrent disease (NPV 98%). On Chi-square analysis T1-2 vs T3-4 tumor, use of CTV margin vs no margin, chemotherapy vs no chemotherapy, smoking history, and tonsil vs base of tongue subsite were not statistically significant in association with positive PTS.

CONCLUSION

PET/CT for post-treatment evaluation of patients treated with PT had an expectedly high NPV of 98% for residual/locoregionally recurrent disease; however, the PPV was 9% (1/11) which is much lower than would be expected with photon-based treatment. These findings may be the result of lingering acute inflammation caused by RBE differences at the distal end of the Bragg peak. Our findings are hypothesis generating and require validation with larger well-matched patient cohorts.

Conditional Prostate Cancer-Specific Survival Probabilities in Recurrent Prostate Cancer Patients Receiving Radiation ± Antiandrogen Therapy: Secondary Analysis of a Randomized Clinical Trial

PURPOSE/OBJECTIVE(S)

Salvage radiation therapy (SRT) and androgen-deprivation therapy (ADT) are routinely used in patients with elevated prostate-specific antigen (PSA) levels after radical prostatectomy (RP) for prostate cancer (PCa). Although prostate cancer-specific survival (PCSS) following SRT is useful when counseling patients at the time of treatment, the utility of this data from time of diagnosis diminishes over time. Conditional survival (CS) can provide more relevant estimates, especially given long-term PCa survivorship. The primary aim of this study was to analyze CS estimates for recurrent PCa patients undergoing SRT ± ADT. The secondary objective was to determine if factors prognostic of PCSS at diagnosis remain relevant in survivorship.

MATERIALS/METHODS

We analyzed data from 760 post-RP patients enrolled in NRG/RTOG 9601 (1998-2003). Eligible patients included men who had undergone prior RP and had pT2/T3 disease without nodal involvement and detectable PSA levels of 0.2-4.0 ng/mL. Patients were randomly assigned to undergo SRT and receive either 24 mo of ADT or placebo. OS was calculated (Kaplan-Meier), cumulative incidence was used to estimate PCSS rates, and prognostic factors associated with PCSS were analyzed by multivariable Cox proportional hazards modeling (MVA).

RESULTS

Patients were followed for a median of 13 y. The 5- and 10-y PCSS estimates from diagnosis were 98.52% and 92.7%, respectively. At 1- (n = 755), 3- (n = 727), 5- (n = 680), and 8-y (n = 602) survivorship, chances of PCSS at an additional 5-y were 97.41%, 95.29%, 93.76%, and 91.04%, respectively. On MVA at diagnosis, omission of ADT (HR 2.156, P = 0.0003), increasing age (HR 1.833, P = 0.03), Gleason score (GS) 7 (HR 2.356, P = 0.0057), and GS 8-10 (HR 4.841, P < 0.0001) were associated with PCa-specific mortality. For those who achieved survivorship at 1-, 3-, 5-, and 8-y, all variables remained prognostic of PCa-specific mortality on MVA.

CONCLUSION

Conditional risk of death from PCa for patients treated with SRT increases over time. The initial risk of dying from PCa over a given period, however, is higher than if already having survived a portion of that period. ADT, younger age, and lower GS continue to confer a reduced risk of PCa-specific mortality for long-term survivors. This data can be used to inform survivorship care planning, giving patients more relevant prognostic information during continued surveillance after completion of treatment.

Relationship Between Spatial Distribution Tumor Location and Dosimetric Outcomes in Patients Receiving Definitive Proton Therapy for Locally Advanced Lung Cancer

PURPOSE/OBJECTIVE(S)

Intensity Modulated Proton Therapy with Pencil Beam Scanning (IMPT/PBS) has been postulated to have dosimetric benefits, especially for sparing of normal tissues in the treatment of thoracic malignancies. Distinguishing which patients may benefit most from IMPT/PBS treatment has important implications when counseling patients on optimal treatment modality, treatment approval turnaround time, and potential toxicities. We herein present a single institution experience assessing the relationship between spatial distribution of tumor location and dosimetric outcomes in patients receiving definitive IMPT/PBS for locally advanced lung cancer.

MATERIALS/METHODS

Consecutive patients treated with IMPT/PBS for locally advanced lung cancer from 2016-2022 at an academic proton center were retrospectively analyzed. Treatment, tumor volume, and patient characteristics were collected. Distance from the posterior pleura to the anterior-most portion of the clinical tumor volume (CTV) of the tumor was measured. A ratio of this distance to the pleura-to-pleura distance at that corresponding lung level was used to classify anterior (>0.7) versus posterior tumors. Dosimetric details including beam angles, dose-volume parameters for the ipsilateral, contralateral, total lung and heart for each patient were recorded. Statistical differences between groups were determined using Wilcoxon Signed Rank test. Pearson's correlation coefficient was used to determine impact of CTV volume and the anterior-most distance of CTV on dosimetric parameters.

RESULTS

Fifty-eight patients treated for Stage IIB-IIIC locally advanced lung cancer with a median CTV volume of 258 cc's were identified and included in this retrospective study. Median age was 68 years and there was an equal distribution of male (29, 50%) and female patients (29, 50%) as well as anterior (>0.7) and posterior lying tumors in this cohort. The majority of patients were white (42, 72%) Forty patients (69%) had right sided lung tumors. Median cumulative dose was 61.2 Gy (range 59.4-70 Gy) while median dose per fraction was 2 Gy (range 1.8-2 Gy). When compared to anterior tumors, posterior tumors had a lower Lung V20 (19.1% vs 21.6%, p = 0.1,), V5 (27.6% vs 32.4%, p = 0.03), Mean Lung (9.9 Gy vs 11.7 Gy, p = 0.04), Mean Heart (4.8 Gy vs 6.3 Gy, p = 0.1), and Heart V50 (3.1% vs. 4.6%, p = 0.15). Anterior-most distance of CTV from the posterior pleura was positively correlated with Lung V20 (r = .435, p = 0.001), Lung V5 (r = .390, p = 0.002), Mean Lung (r = .479, p = 0.001), Mean Heart (r = .304, p = 0.020), and Heart V50 (r = .322, p = 0.014). CTV volume was also significantly positively correlated (p <.01) with these parameters.

CONCLUSION

Spatial distribution and treatment volume size are predictive of dosimetric outcomes for locally advanced lung cancer. Posterior lying tumors may derive greater dosimetric advantage when compared to anterior lesions when utilizing IMPT/PBS.

Conditional Risk and Predictive Factors Associated with Late Toxicity for Prostate Cancer Patients Treated with External Beam Radiotherapy Alone on Randomized Trial RTOG 0126

PURPOSE/OBJECTIVE(S)

Patients with localized prostate cancer (PCA) treated with RT alone have excellent outcomes, making quality of life and minimization of toxicities of great concern. The risk of developing toxicity may evolve with time from treatment which is of interest to patients seen in follow up. The primary objective of this study is to determine the conditional risk of grade 2+ GI or GU toxicity for patients treated with RT. A secondary objective is to determine risk factors associated with the development of late toxicities.

MATERIALS/METHODS

We performed a post-hoc analysis of RTOG 0126, which enrolled patients with intermediate risk PCa who were randomized to receive standard dose RT of 70.2 Gy in 39 fractions vs dose escalated dose RT (DE-RT) of 79.2 Gy in 44 fractions. Cumulative incidence was used to calculate risk of grade 2+ GU and grade 2+ GI toxicity at initial time points, as well as for patients who survived 2 years and 5 years without respective grade 2+ toxicity. Risk factors of age, race, urinary incontinence, baseline urinary frequency, acute GU toxicity, treatment arm, RT method (3DCRT vs IMRT), and OAR contouring protocol violation were analyzed using univariate and multivariate Cox proportional hazards modeling for late GU toxicity. Risk factors of age, race, RT method, acute GI toxicity, DE-RT, RT method, and OAR contouring protocol violation were analyzed for late GI toxicity.

RESULTS

One thousand four hundred ninety-nine patients with a median follow up of 8.4 years (range 0.02-13 years) were included for analysis. The conditional cumulative 5-year risk of late grade 2+ GI toxicity at enrollment, 2-, and 5-years of grade 2+GI toxicity free survivorship was 14.7%, 6.2%, and 1.8% respectively. The cumulative 5-year risk of late grade 2+ GU toxicity at enrollment, 2-, and 5-years of late grade 2+ GU toxicity free survivorship was 7.9%, 4.7%, and 2.7% respectively. Initially DE-RT (HR 1.401, 95% CI 1.099-1.787; p = 0.0066), acute GI toxicity (HR 1.962, 95% CI 1.271-2.616; P<0.0001), and black race (HR 0.630, 95% CI 0.4-0.993; p<0.0463) were predictive of late GI toxicity. After two years of 2+ GI toxicity free survivorship, only acute GI toxicity (HR 2.015, 95% CI 1.238-3.279, p<0.0048) remained predictive of late GI toxicity on MVA. DE-RT (HR 1.616, 95% CI 1.187-2.2, p<0.0023), IMRT (HR 0.559, 95% CI 0.389-0.804, p = 0.0017), and urinary frequency at baseline (HR 1.377, 95% CI 1-1.895 p<0.0498) were predictive of late GU toxicity at enrollment.

CONCLUSION

This data suggests that as patients proceed further from completion of EBRT, the conditional risk of late toxicity decreases. The majority of grade 2+ GI and GU toxicities occur in the first two years of treatment and patients who have not had a grade 2+ GU or GI toxicity within the first five years are likely to remain toxicity free. Factors such as presence of baseline urinary dysfunction, presence of acute toxicities, DE-RT, and radiation modality predict for late toxicity. These findings are of relevance for clinicians and patients in the post treatment setting.

Post-treatment PET/CT for p16-positive oropharynx cancer treated with definitive proton therapy

Objectives

Given emerging data suggesting that uncertainty in the relative biologic effectiveness at the distal end of the Bragg peak results in increased mucosal injury in patients with oropharynx cancer receiving adjuvant proton therapy, we evaluated the results of post-treatment positron emission tomography-computed tomography (PET/CT) in patients with p16-positive oropharynx cancer (p16+OPC) treated with definitive intensity-modulated proton therapy (IMPT).

Material and Methods

A retrospective cohort study of patients with p16+OPC treated with definitive IMPT between 2016 and 2022 was performed at a single institution. Patients with PET/CT scans within 6 months following completion of IMPT were included in the study. Positive post-treatment scans were defined by a maximum standard uptake values (SUVmax) >4.0 or a <65% reduction in SUVmax in either the primary tumor or lymph node. The Fisher's exact test was used to evaluate factors associated with positive post-treatment PET/ CT values.

Results

Sixty-two patients were included for analysis. Median follow-up was 21 months (range: 3-71 months) with a median time to post-treatment PET/CT of 3 months (range: 2-6 months). Median post-treatment SUVmax of the primary disease and nodal disease was 0 (mean: 0.8, range: 0-7.7) and 0 (mean: 0.7, range: 0-9.5), respectively. Median post-treatment percent reduction in SUVmax for the primary site and lymph node was 100% (mean: 94%, range: 31.3-100%) and 100% (mean: 89%, range: 23-100%), respectively. Eleven patients had a positive post-treatment PET/CT with one biopsy-proven recurrence. Negative and positive predictive values (NPV and PPV) were 98% and 9.1%, respectively. There were no factors associated with positive post-treatment PET/CT.

Conclusion

Similar to patients treated with photon-based radiation therapy, post-treatment PET/CT has a high NPV for patients with p16+OPC treated with definitive proton therapy and should be used to guide patient management. Additional patients and more events are needed to confirm the PPV of a post-treatment PET/CT in this favorable patient cohort.

Conditional Risks of Biochemical Failure and Prostate Cancer-Specific Death in Patients Undergoing External Beam Radiotherapy: A Secondary Analysis of 2 Randomized Clinical Trials

Importance

As patients achieve years of survival after treatment for prostate cancer, the risk of biochemical failure (BF) or prostate cancer-specific death (PCSD) may evolve over time, with clinical relevance to both patients and clinicians.

Objective

To determine conditional BF-free survival, PSCD, and overall survival estimates for patients with low- or intermediate-risk prostate cancer enrolled in the Radiation Therapy Oncology Group (RTOG) 0126 and RTOG 0415 clinical trials. A secondary objective was to determine whether prognostic factors at diagnosis remain relevant at later points in follow-up.

Design, Setting, and Participants

A pooled secondary analysis of patients treated with external-beam radiotherapy alone and enrolled in the prospective randomized clinical trials RTOG 0126 and RTOG 0415 was performed. Patients included for analysis were enrolled between March 2002 and December 2009 with a median follow-up of 6.9 years. Overall survival was calculated using the Kaplan-Meier method at various survivorship time points. Cumulative incidence was used to calculate BF rates using the Phoenix definition, as well as PCSD. Risk factors such as Gleason score, tumor (T) stage, prostate-specific antigen level, and the equivalent dose in 2 Gy fractions of prescribed dose were analyzed at different time points using multivariable Cox proportional hazards modeling. Data were analyzed from November 2021 to February 2023.

Main Outcomes and Measures

Conditional risks of BF and PCSD after completion of external-beam radiotherapy.

Results

A total of 2591 patients (median [IQR] age, 69 [63-73] years) were included in the study with a mean (range) PSA level of 7.1 (4.7-8.9) ng/mL, 1334 patients (51.5%) with a Gleason score 6 disease, and 1706 patients (65.8%) with T1 disease. Rates of BF from time of treatment were 1.63% (95% CI, 1.20%-2.18%) at 1 year, 7.04% (95% CI, 6.09%-8.08%) at 3 years, 12.54% (95% CI, 11.28%-13.88%) at 5 years, and 22.32% (95% CI, 20.46%-24.24%) at 8 years. For patients surviving 1, 3, and 5 years without BF, the rates of BF in the next 5 years were 14.20% (95% CI, 12.80%-15.66%), 17.19% (95% CI, 15.34%-19.14%), and 18.85% (95% CI, 16.21%-21.64%), respectively. At the initial time point, the rate of PCSD in the next 5 years was 0.66% (95% CI, 0.39%-1.04%). For patients who achieved 1, 3, 5, and 8 years of survivorship, the rates of PCSD in the next 5 years were 1.16% (95% CI, 0.77-1.67) at 1 year, 2.42% (95% CI, 1.74%-3.27%) at 3 years, 2.88% (95% CI, 2.01%-3.99%) at 5 years, and 3.49% (95% CI, 0.98%-8.73%) at 8 years.

Conclusions and Relevance

In this secondary analysis of 2 randomized clinical trials of patients undergoing external beam radiotherapy for prostate cancer, the conditional risks of BF and death from prostate cancer increased with time for patients with low- and intermediate-risk prostate cancer treated with radiotherapy alone. These results could inform optimal trial design and may be helpful information for patients evaluated in follow-up.

Trial Registration

ClinicalTrials.gov Identifier: NCT00033631; NCT00331773.

Identification of CT-based non-invasive Radiographic Biomarkers for Overall Survival Stratification in Oral Cavity Squamous Cell Carcinoma

This study addresses the limited non-invasive tools for Oral Cavity Squamous Cell Carcinoma OSCC survival prediction by identifying Computed Tomography (CT)-based biomarkers for improved prognosis. A retrospective analysis was conducted on data from 149 OSCC patients, including radiomics and clinical. An ensemble approach involving correlation analysis, score screening, and the Sparse-L1 algorithm was used to select functional features, which were then used to build Cox Proportional Hazards models (CPH). Our CPH achieved a 0.70 concordance index in testing. The model identified two CT-based radiomics features, Gradient-Neighboring-Gray-Tone-Difference-Matrix-Strength (GNS) and normalized-Wavelet-LLL-Gray-Level-Dependence-Matrix-Large-Dependence-High-Gray-Level-Emphasis (HLE), as well as smoking and alcohol usage, as survival biomarkers. The GNS group with values above 14 showed a hazard ratio of 0.12 and a 3-year survival rate of about 90%. Conversely, the GNS group with values less than or equal to 14 had a 49% survival rate. For normalized HLE, the high-end group (HLE > -0.415) had a hazard ratio of 2.41, resulting in a 3-year survival rate of 70%, while the low-end group (HLE <= -0.415) had a 36% survival rate. These findings contribute to our knowledge of how radiomics can be used to anticipate the outcome and tailor treatment plans from people with OSCC.

Multi-institutional study of clinical outcomes of patients with head and neck cancer presenting with cN3 disease

BACKGROUND

To evaluate disease control, toxicities, and variables associated with clinical outcomes for patients with head and neck squamous cell carcinoma and clinical N3 disease (HNSCC N3) treated with definitive chemoradiation therapy.

METHODS

We performed a retrospective review of patients with HNSCC N3 treated at two high-volume academic centers between 1996 and 2019.

RESULTS

We identified 85 patients with a median follow-up of 2.8 years. Five-year overall survival, regional control, and freedom from distant metastases rates were 38%, 80%, and 80%, respectively. Severe complications were identified in 19% of patients.

CONCLUSIONS

Favorable regional control is achievable with definitive chemoradiation therapy for patients with HNSCC N3 disease. Distant metastases are a common pattern of failure and should be a focus of prospective study.

Gross tumor volume margin and local control in p16-positive oropharynx cancer patients treated with intensity modulated proton therapy

BACKGROUND

To determine if the extent of high-dose gross tumor volume (GTV) to clinical target volume (CTV) expansion is associated with local control in patients with p16-positive oropharynx cancer (p16+ OPC) treated with definitive intensity modulated proton therapy (IMPT).

METHODS

We performed a retrospective analysis of patients with p16+ OPC treated with IMPT at a single institution between 2016 and 2021. Patients with a pre-treatment PET-CT and restaging PET-CT within 4 months following completion of IMPT were analyzed.

RESULTS

Sixty patients were included for analysis with a median follow-up of 17 months. The median GTV to CTV expansion was 5 mm (IQR: 2 mm). Thirty-three percent of patients (20 of 60) did not have a GTV to CTV expansion. There was one local failure within the expansion group (3%).

CONCLUSION

Excellent local control was achieved using IMPT for p16+ OPC independent of GTV expansion. IMPT with minimal target expansions represent a potential harm-minimization technique for p16-positive oropharynx cancer.

Federated learning enables big data for rare cancer boundary detection

Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizability is concerning. This is currently addressed by sharing multi-site data, but such centralization is challenging/infeasible to scale due to various limitations. Federated ML (FL) provides an alternative paradigm for accurate and generalizable ML, by only sharing numerical model updates. Here we present the largest FL study to-date, involving data from 71 sites across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, reporting the largest such dataset in the literature (n = 6, 314). We demonstrate a 33% delineation improvement for the surgically targetable tumor, and 23% for the complete tumor extent, over a publicly trained model. We anticipate our study to: 1) enable more healthcare studies informed by large diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further analyses for glioblastoma by releasing our consensus model, and 3) demonstrate the FL effectiveness at such scale and task-complexity as a paradigm shift for multi-site collaborations, alleviating the need for data-sharing.

NIMG-39. RADIOMIC ANALYSIS FOR NON-INVASIVE IN VIVO PROGNOSTIC STRATIFICATION OF DE NOVO GLIOBLASTOMA PATIENTS: A MULTI-INSTITUTIONAL EVALUATION FOR GENERALIZABILITY IN THE RESPOND CONSORTIUM

PURPOSE

Multi-parametric MRI based radiomic signatures have highlighted the promise of artificial intelligence (AI) in neuro-oncology. However, inter-institution heterogeneity hinders generalization to data from unseen clinical institutions. To this end, we formulated the ReSPOND (Radiomics Signatures for PrecisiON Diagnostics) consortium for glioblastoma. Here, we seek non-invasive generalizable radiomic signatures from routine clinically-acquired MRI for prognostic stratification of glioblastoma patients.

METHODS

We identified a retrospective cohort of 606 patients with near/gross total tumor resection ( &gt;90%), from 13 geographically-diverse institutions. All pre-operative structural MRI scans (T1,T1-Gd,T2,T2-FLAIR) were aligned to a common anatomical atlas. An automatic algorithm segmented the whole tumors (WTs) into 3 sub-compartments, i.e., enhancing (ET), necrotic core (NC), and peritumoral T2-FLAIR signal abnormality (ED). The combination of ET+NC defines the tumor core (TC). Quantitative radiomic features were extracted to generate our AI model to stratify patients into short- (&lt; 14mts) and long-survivors ( &gt;14mts). The model trained on 276 patients from a single institution was independently validated on 330 unseen patients from 12 left-out institutions, using the area-under-the-receiver-operating-characteristic-curve (AUC).

RESULTS

Each feature individually offered certain (limited but reproducible) value for identifying short-survivors: 1) TC closer to lateral ventricles (AUC=0.62); 2) larger ET/brain (AUC=0.61); 3) larger TC/brain (AUC=0.59); 4) larger WT/brain (AUC=0.55); 5) larger ET/WT (AUC=0.59); 6) smaller ED/WT (AUC=0.57); 7) larger ventricle deformations (AUC=0.6). Integrating all features and age, through a multivariate AI model, resulted in higher accuracy (AUC=0.7; 95% C.I.,0.64-0.77).

CONCLUSION

Prognostic stratification using basic radiomic features is highly reproducible across diverse institutions and patient populations. Multivariate integration yields relatively more accurate and generalizable radiomic signatures, across institutions. Our results offer promise for generalizable non-invasive in vivo signatures of survival prediction in patients with glioblastoma. Extracted features from clinically-acquired imaging, renders these signatures easier for clinical translation. Large-scale evaluation could contribute to improving patient management and treatment planning.

*Indicates equal authorship.

NIMG-22. PREDICTION OF GLIOBLASTOMA CELLULAR INFILTRATION AND RECURRENCE USING MACHINE LEARNING AND MULTI-PARAMETRIC MRI ANALYSIS: RESULTS FROM THE MULTI-INSTITUTIONAL RESPOND CONSORTIUM

PURPOSE

Multi-parametric MRI and artificial intelligence (AI) methods were previously used to predict peritumoral neoplastic cell infiltration and risk of future recurrence in glioblastoma, in single-institution studies. We hypothesize that important characteristics of peritumoral tissue heterogeneity captured, engineered/selected, and quantified by these methods relate to predictions generalizable in the multi-institutional ReSPOND (Radiomics Signatures for PrecisiON Diagnostics) consortium.

METHODS

To support further development, generalization, and clinical translation of our proposed method, we trained the AI model on a retrospective cohort of 29 de novo glioblastoma patients from the Hospital of the University of Pennsylvania (UPenn) (Male/Female:20/9, age:22-78 years) followed by evaluation on a prospective multi-institutional cohort of 84 glioblastoma patients (Male/Female:51/33, age:34-89 years) from Case Western Reserve University/University Hospitals (CWRU/UH, 25), New York University (NYU, 13), Ohio State University (OSU, 13), University Hospital Río Hortega (RH, 2), and UPenn (31). Features extracted from pre-resection MRI (T1, T1-Gd, T2, T2-FLAIR, ADC) were used to build our model predicting the spatial pattern of subsequent tumor recurrence. These predictions were evaluated against regions of pathology-confirmed post-resection recurrence.

RESULTS

Our model predicted the locations that later harbored tumor recurrence with sensitivity 83%, AUC 0.83 (99% CI, 0.73-0.93), and odds ratio 7.23 (99% CI, 7.09-7.37) in the prospective cohort. Odds ratio (99% CI)/AUC(99% CI) per institute were: CWRU/UH, 7.8(7.6-8.1)/0.82(0.75-0.89); NYU, 3.5(3.3-3.6)/0.84(074-0.93); OSU, 7.9(7.6-8.3)/0.8(0.67-0.94); RH, 22.7(20-25.1)/0.94(0.27-1); UPenn, 7.1(6.8-7.3)/0.83(0.76-0.91).

CONCLUSION

This is the first study that provides relatively extensive multi-institutional validated evidence that AI can provide good predictions of peritumoral neoplastic cell infiltration and future recurrence, by dissecting the MRI signal heterogeneity in peritumoral tissue. Our analyses leveraged the unique dataset of the ReSPOND consortium, which aims to develop and evaluate AI-based biomarkers for individualized prediction and prognostication, by moving from single-institution studies to generalizable, well-validated multi-institutional predictive biomarkers.

Immune checkpoint inhibition in patients treated with stereotactic radiation for brain metastases

Purpose

Stereotactic radiation therapy (SRT) and immune checkpoint inhibitors (ICI) may act synergistically to improve treatment outcomes but may also increase the risk of symptomatic radiation necrosis (RN). The objective of this study was to compare outcomes for patients undergoing SRT with and without concurrent ICI.

Methods and materials

Patients treated for BMs with single or multi-fraction SRT were retrospectively reviewed. Concurrent ICI with SRT (SRT-ICI) was defined as administration within 3 months of SRT. Local control (LC), radiation necrosis (RN) risk and distant brain failure (DBF) were estimated by the Kaplan-Meier method and compared between groups using the log-rank test. Wilcoxon rank sum and Chi-square tests were used to compare covariates. Multivariate cox regression analysis (MVA) was performed.

Results

One hundred seventy-nine patients treated with SRT for 385 brain lesions were included; 36 patients with 99 lesions received SRT-ICI. Median follow up was 10.3 months (SRT alone) and 7.7 months (SRT- ICI) (p = 0.08). Lesions treated with SRT-ICI were more commonly squamous histology (17% vs 8%) melanoma (20% vs 2%) or renal cell carcinoma (8% vs 6%), (p < 0.001). Non-small cell lung cancer (NSCLC) compromised 60% of patients receiving ICI (n = 59). Lesions treated with SRT-ICI had significantly improved 1-year local control compared to SRT alone (98 and 89.5%, respectively (p = 0.0078). On subset analysis of NSCLC patients alone, ICI was also associated with improved 1 year local control (100% vs. 90.1%) (p = 0.018). On MVA, only tumor size ≤2 cm was significantly associated with LC (HR 0.38, p = 0.02), whereas the HR for concurrent ICI with SRS was 0.26 (p = 0.08). One year DBF (41% vs. 53%; p = 0.21), OS (58% vs. 56%; p = 0.79) and RN incidence (7% vs. 4%; p = 0.25) were similar for SRT alone versus SRT-ICI, for the population as a whole and those patients with NSCLC.

Conclusion

These results suggest SRT-ICI may improve local control of brain metastases and is not associated with an increased risk of symptomatic radiation necrosis in a cohort of predominantly NSCLC patients. Larger, prospective studies are necessary to validate these findings and better elucidate the impact of SRT-ICI on other disease outcomes.

Brain extraction on MRI scans in presence of diffuse glioma: Multi-institutional performance evaluation of deep learning methods and robust modality-agnostic training

Brain extraction, or skull-stripping, is an essential pre-processing step in neuro-imaging that has a direct impact on the quality of all subsequent processing and analyses steps. It is also a key requirement in multi-institutional collaborations to comply with privacy-preserving regulations. Existing automated methods, including Deep Learning (DL) based methods that have obtained state-of-the-art results in recent years, have primarily targeted brain extraction without considering pathologically-affected brains. Accordingly, they perform sub-optimally when applied on magnetic resonance imaging (MRI) brain scans with apparent pathologies such as brain tumors. Furthermore, existing methods focus on using only T1-weighted MRI scans, even though multi-parametric MRI (mpMRI) scans are routinely acquired for patients with suspected brain tumors. In this study, we present a comprehensive performance evaluation of recent deep learning architectures for brain extraction, training models on mpMRI scans of pathologically-affected brains, with a particular focus on seeking a practically-applicable, low computational footprint approach, generalizable across multiple institutions, further facilitating collaborations. We identified a large retrospective multi-institutional dataset of n=3340 mpMRI brain tumor scans, with manually-inspected and approved gold-standard segmentations, acquired during standard clinical practice under varying acquisition protocols, both from private institutional data and public (TCIA) collections. To facilitate optimal utilization of rich mpMRI data, we further introduce and evaluate a novel ''modality-agnostic training'' technique that can be applied using any available modality, without need for model retraining. Our results indicate that the modality-agnostic approach1 obtains accurate results, providing a generic and practical tool for brain extraction on scans with brain tumors.

Advanced magnetic resonance imaging in glioblastoma: a review

Glioblastoma, the most common and most rapidly progressing primary malignant tumor of the central nervous system, continues to portend a dismal prognosis, despite improvements in diagnostic and therapeutic strategies over the last 20 years. The standard of care radiographic characterization of glioblastoma is magnetic resonance imaging (MRI), which is a widely utilized examination in the diagnosis and post-treatment management of patients with glioblastoma. Basic MRI modalities available from any clinical scanner, including native T1-weighted (T1w) and contrast-enhanced (T1CE), T2-weighted (T2w), and T2-fluid-attenuated inversion recovery (T2-FLAIR) sequences, provide critical clinical information about various processes in the tumor environment. In the last decade, advanced MRI modalities are increasingly utilized to further characterize glioblastomas more comprehensively. These include multi-parametric MRI sequences, such as dynamic susceptibility contrast (DSC), dynamic contrast enhancement (DCE), higher order diffusion techniques such as diffusion tensor imaging (DTI), and MR spectroscopy (MRS). Significant efforts are ongoing to implement these advanced imaging modalities into improved clinical workflows and personalized therapy approaches. Functional MRI (fMRI) and tractography are increasingly being used to identify eloquent cortices and important tracts to minimize postsurgical neuro-deficits. A contemporary review of the application of standard and advanced MRI in clinical neuro-oncologic practice is presented here.

Immune biomarkers of treatment failure for a patient on a phase I clinical trial of pembrolizumab plus radiotherapy

BACKGROUND

Pembrolizumab is a monoclonal antibody that is designed against programmed cell death protein 1 (PD-1). Pembrolizumab and other immunocheckpoint-blocking monoclonal antibodies work by modulating a patient's own immune system to increase anti-tumor activity. While immunocheckpoint blockade has shown promising results, only 20-40 % of patients experience objective clinical benefit. Differences in individual tumor biology and the presence multiple immune checkpoints present a challenge for treatment. Because radiotherapy has immunomodulatory effects on the tumor microenvironment, it has the potential to synergize with immunotherapy and augment tumor response. NCT02318771 is a phase 1 clinical trial designed to investigate the immunomodulatory effects of radiation therapy in combination with pembrolizumab.

CASE PRESENTATION

The patient is a 64-year-old male with metastatic clear cell renal cell carcinoma, Fuhrman grade 4, pathologically staged as T3 N0. Metastatic disease was well controlled for several years with sunitinib. Following disease progression, he was switched to axitinib. When disease progression continued, the patient was enrolled in NCT02318771, a phase 1 clinical trial combining radiotherapy and pembrolizumab. The patient experienced unusually rapid disease progression during treatment, which was confirmed by repeated CT scans to rule out pseudoprogression. Tissue biopsies and peripheral blood draws were obtained before, during, and after treatment. Samples were analyzed to provide plausible rationale for rapid treatment failure.

CONCLUSIONS

Biomarker analysis demonstrated an absence of TILs, which may be a cause of treatment failure as pembrolizumab works through T cell-dependent mechanisms. Furthermore, the presence of other non-redundant immune checkpoints in the periphery and tumor microenvironment presents a treatment challenge. Additionally, the radiation dose and fractionation schedule may have played a role in treatment failure as these factors play a role in the effect radiotherapy on the tumor microenvironment as well as the potential for synergy with immunotherapy.

TRIAL REGISTRATION

An Exploratory Study to Investigate the Immunomodulatory Activity of Radiation Therapy (RT) in Combination With MK-3475 in Patients With Recurrent/Metastatic Head and Neck, Renal Cell Cancer, Melanoma and Lung Cancer, NCT02318771 .

Sucking behaviour and milk intake in jaundiced neonates

Twenty seven healthy newborn infants who developed hyperbilirubinaemia during the first week of life were investigated by daily test feeds between the second and sixth days of life. Nutritive sucking was assessed by measurement of rate, duration and pressure of sucking and by clinical observation. Milk consumption, duration and pressure of sucking all showed a significant increase during the period of study. Sucking rate did not vary with age. Significant correlation of sucking time and sucking pressure with milk intake were observed. Serum bilirubin levels showed no correlation with milk consumption on each day of the study or with the pooled data of feeding parameters when compared independently of post-natal age. Hyperbilirubinaemia was significantly correlated with the infants who appeared disinterested in feeds when assessed by clinical observations of apparent hunger and alertness at the onset of the test feed. However, milk intake was not impaired in these infants.