Radiation Versus Immune Checkpoint Inhibitor Associated Pneumonitis: Distinct Radiologic Morphologies.

BACKGROUND: Patients with non-small cell lung cancer may develop pneumonitis after thoracic radiotherapy (RT) and immune checkpoint inhibitors (ICIs). We hypothesized that distinct morphologic features are associated with different pneumonitis etiologies. MATERIALS AND METHODS: We systematically compared computed tomography (CT) features of RT- versus ICI-pneumonitis. Clinical and imaging features were tested for association with pneumonitis severity. Lastly, we constructed an exploratory radiomics-based machine learning (ML) model to discern pneumonitis etiology. RESULTS: Between 2009 and 2019, 82 patients developed pneumonitis: 29 after thoracic RT, 23 after ICI, and 30 after RT + ICI. Fifty patients had grade 2 pneumonitis, 22 grade 3, and 7 grade 4. ICI-pneumonitis was more likely bilateral (65% vs. 28%; p = .01) and involved more lobes (66% vs. 45% involving at least three lobes) and was less likely to have sharp border (17% vs. 59%; p = .004) compared with RT-pneumonitis. Pneumonitis morphology after RT + ICI was heterogeneous, with 47% bilateral, 37% involving at least three lobes, and 40% sharp borders. Among all patients, risk factors for severe pneumonitis included poor performance status, smoking history, worse lung function, and bilateral and multifocal involvement on CT. An ML model based on seven radiomic features alone could distinguish ICI- from RT-pneumonitis with an area under the receiver-operating curve of 0.76 and identified the predominant etiology after RT + ICI concordant with multidisciplinary consensus. CONCLUSION: RT- and ICI-pneumonitis exhibit distinct spatial features on CT. Bilateral and multifocal lung involvement is associated with severe pneumonitis. Integrating these morphologic features in the clinical management of patients who develop pneumonitis after RT and ICIs may improve treatment decision-making. IMPLICATIONS FOR PRACTICE: Patients with non-small cell lung cancer often receive thoracic radiation and immune checkpoint inhibitors (ICIs), both of which can cause pneumonitis. This study identified similarities and differences in pneumonitis morphology on computed tomography (CT) scans among pneumonitis due to radiotherapy (RT) alone, ICI alone, and the combination of both. Patients who have bilateral CT changes involving at least three lobes are more likely to have ICI-pneumonitis, whereas those with unilateral CT changes with sharp borders are more likely to have radiation pneumonitis. After RT and/or ICI, severe pneumonitis is associated with bilateral and multifocal CT changes. These results can help guide clinicians in triaging patients who develop pneumonitis after radiation and during ICI treatment.

Isolated progression of metastatic lung cancer: Clinical outcomes associated with definitive radiotherapy.

BACKGROUND: Progressive, metastatic non-small cell lung cancer (NSCLC) often requires the initiation of new systemic therapy. However, in patients with NSCLC that is oligoprogressive (≤3 lesions), local radiotherapy (RT) may allow for the eradication of resistant microclones and, therefore, the continuation of otherwise effective systemic therapy. METHODS: Patients treated from 2008 to 2019 with definitive doses of RT to all sites of intracranial or extracranial oligoprogression without a change in systemic therapy were identified. Radiographic progression-free survival (rPFS) and time to new therapy (TNT) were measured. Associations between baseline clinical and treatment-related variables were correlated with progression-free survival via Cox proportional hazards modeling. RESULTS: Among 198 unique patients, 253 oligoprogressive events were identified. Intracranial progression occurred in 51% of the patients, and extracranial progression occurred in 49%. In the entire cohort, the median rPFS was 7.9 months (95% CI, 6.5-10.0 months), and the median TNT was 8.8 months (95% CI, 7.2-10.9 months). On adjusted modeling, patients with the following disease characteristics were associated with better rPFS: better performance status (P = .003), fewer metastases (P = .03), longer time to oligoprogression (P = .009), and fewer previous systemic therapies (P = .02). Having multiple sites of oligoprogression was associated with worse rPFS (P < .001). CONCLUSIONS: In select patients with oligoprogression, definitive RT is a feasible treatment option to delay the initiation of next-line systemic therapies, which have more limited response rates and efficacy. Further randomized prospective data may help to validate these findings and identify which patients are most likely to benefit.

Hospitalization and definitive radiotherapy in lung cancer: incidence, risk factors and survival impact.

BACKGROUND: Unplanned hospitalization during cancer treatment is costly, can disrupt treatment, and affect patient quality of life. However, incidence and risks factors for hospitalization during lung cancer radiotherapy are not well characterized. METHODS: Patients treated with definitive intent radiation (≥45 Gy) for lung cancer between 2008 and 2018 at a tertiary academic institution were identified. In addition to patient, tumor, and treatment related characteristics, specific baseline frailty markers (Charlson comorbidity index, ECOG, patient reported weight loss, BMI, hemoglobin, creatinine, albumin) were recorded. All cancer-related hospitalizations during or within 30 days of completing radiation were identified. Associations between baseline variables and any hospitalization, number of hospitalizations, and overall survival were identified using multivariable linear regression and multivariable Cox proportional-hazards models, respectively. RESULTS: Of 270 patients included: median age was 66.6 years (31-88), 50.4% of patients were male (n = 136), 62% were Caucasian (n = 168). Cancer-related hospitalization incidence was 17% (n = 47), of which 21% of patients hospitalized (n = 10/47) had > 1 hospitalization. On multivariable analysis, each 1 g/dL baseline drop in albumin was associated with a 2.4 times higher risk of any hospitalization (95% confidence interval (CI) 1.2-5.0, P = 0.01), and baseline hemoglobin ≤10 was associated with, on average, 2.7 more hospitalizations than having pre-treatment hemoglobin > 10 (95% CI 1.3-5.4, P = 0.01). After controlling for baseline variables, cancer-related hospitalization was associated with 1.8 times increased risk of all-cause death (95% CI: 1.02-3.1, P = 0.04). CONCLUSIONS: Our data show baseline factors can predict those who may be at increased risk for hospitalization, which was independently associated with increased mortality. Taken together, these data support the need for developing further studies aimed at early and aggressive interventions to decrease hospitalizations during treatment.

Lung cancer and family-centered concerns.

BACKGROUND: Genetic and environmental interactions predispose certain groups to lung cancer, including families. Families or caregiving units experience the disease interdependently. We have previously evaluated the concerns and preferences of patients in addressing the lung cancer experience and cancer risks in their families. This qualitative study evaluates the concerns and preferences of family members and caregivers of patients with lung cancer in the lung cancer experience and familial cancer risks. METHODS: We held focus groups to discuss the format and timing of addressing these preferences and concerns. Qualitative data generated was analyzed using a grounded theory approach. RESULTS: Five focus groups totaling 19 participants were conducted. Seven themes were identified: (1) journey to lung cancer diagnosis has core dimensions for patient and family, (2) importance of communication between patients, families, and providers, (3) challenges for caregivers and family, (4) mixed perceptions of lung cancer causation among relatives, (5) discussion of cancer risk with relatives has complex dynamics, (6) impact of diagnosis on family health behaviors and screening, (7) role of genetic counseling. CONCLUSIONS: Family members of patients with lung cancer are interested in discussing risk factors, prevention, and diagnoses and also would like access to other supportive services do learn about and cope with some of the stresses and barriers they experience in the family lung cancer journey. The diagnosis represents a potential teachable moment with the opportunity to reduce the risk of LC development or improve early detection in LC patient's family members.

A prospective evaluation of whole brain volume loss and neurocognitive decline following hippocampal-sparing prophylactic cranial irradiation for limited-stage small-cell lung cancer.

INTRODUCTION: This study evaluated an association between whole brain volume loss and neurocognitive decline following prophylactic cranial irradiation (PCI) for limited-stage small-cell lung cancer (SCLC). METHODS: This was a secondary analysis of a prospective clinical trial that accrued patients at a single institution from 2013 to 2016. Patients with limited-stage SCLC treated with standard chemo-radiation received PCI 25 Gy/10 fractions, with mean hippocampal dose limited to < 8 Gy. Whole brain volumes were measured using MR imaging obtained before and at 6, 12, 18, and 24 months after PCI. Verbal memory was measured by the Hopkins Verbal Learning Test-Revised (HVLT-R) before and at 6 and 12 months after PCI. Univariate and multivariate linear regression evaluated associations between changes in whole brain volume and verbal memory. RESULTS: Twenty-two patients enrolled. The median whole brain volume before PCI was 1301 mL. Subsequent reduction in whole brain volume was greatest at 18 months after PCI (median change - 23 mL, range - 142 to 20, p = 0.03). At 6 months after PCI, reduction in volume was independently associated with decline in verbal memory, measured by two components of the HVLT-R (Delayed Recall: 0.06/mL volume change, p = 0.046; Percent Retained: 0.66/mL volume change, p = 0.030), when controlling for education and global cognitive function at baseline. CONCLUSION: This is the first study to correlate reduction in whole brain volume and decline in neurocognitive function following whole brain radiation therapy (WBRT). This suggests that loss of brain volume after WBRT may be clinically significant and subsequently impact cognition and quality of life.

Pleural fluid secondary to pulmonary cryptococcal infection: a case report and review of the literature.

BACKGROUND: Pulmonary Cryptococcosis (PC) is diagnosed with increasing incidence in recent years, but it does not commonly involve the pleural space. Here, we report a HIV-negative case with advanced stage IIIB non-small cell lung cancer (NSCLC) treated with radiation therapy presented with dyspnea, a new PET-positive lung mass and bilateral pleural effusion suspecting progressive cancer. However, the patient has been diagnosed as pulmonary cryptococcal infection and successfully treated with oral fluconazole therapy. CASE PRESENTATION: A 77-year-old male with advanced stage non-small cell lung cancer treated with combined chemo-radiation therapy who presented with progressive dyspnea, a new PET-positive left lower lobe lung mass and bilateral pleural effusions. Initial diagnostic thoracentesis and bronchoscopy yielded no cancer, but instead found yeast forms consistent with cryptococcal organisms in the transbronchial biopsies of the left lower lobe lung mass. Subsequent to this, the previously collected pleural fluid culture showed growth of Cryptococcus neoformans. The same sample of pleural effusion was tested and was found to be positive for crytococcal antigen (CrAg) by a lateral flow assay (LFA). The patient has been treated with oral fluconazole therapy resulting in gradual resolution of the nodular infiltrates. CONCLUSION: PC should be considered in immunosuppressed cancer patients. Additionally, concomitant pleural involvement in pulmonary cryptococcal infections may occur. The incidence of false positive 18FDG-PET scans in granulomatous infections and the use of CrAg testing in pleural fluid to aid in diagnosis are reviewed.

Added Value of Computer-aided CT Image Features for Early Lung Cancer Diagnosis with Small Pulmonary Nodules: A Matched Case-Control Study.

Purpose To test whether computer-aided diagnosis (CAD) approaches can increase the positive predictive value (PPV) and reduce the false-positive rate in lung cancer screening for small nodules compared with human reading by thoracic radiologists. Materials and Methods A matched case-control sample of low-dose computed tomography (CT) studies in 186 participants with 4-20-mm noncalcified lung nodules who underwent biopsy in the National Lung Screening Trial (NLST) was selected. Variables used for matching were age, sex, smoking status, chronic obstructive pulmonary disease status, body mass index, study year of the positive screening test, and screening results. Studies before lung biopsy were randomly split into a training set (70 cancers plus 70 benign controls) and a validation set (20 cancers plus 26 benign controls). Image features from within and outside dominant nodules were extracted. A CAD algorithm developed from the training set and a random forest classifier were applied to the validation set to predict biopsy outcomes. Receiver operating characteristic analysis was used to compare the prediction accuracy of CAD with the NLST investigator's diagnosis and readings from three experienced and board-certified thoracic radiologists who used contemporary clinical practice guidelines. Results In the validation cohort, the area under the receiver operating characteristic curve for CAD was 0.9154. By default, the sensitivity, specificity, and PPV of the NLST investigators were 1.00, 0.00, and 0.43, respectively. The sensitivity, specificity, PPV, and negative predictive value of CAD and the three radiologists' combined reading were 0.95, 0.88, 0.86, and 0.96 and 0.70, 0.69, 0.64, and 0.75, respectively. Conclusion CAD could increase PPV and reduce the false-positive rate in the early diagnosis of lung cancer. © RSNA, 2017 Online supplemental material is available for this article.

External beam radiation therapy combined with airway stenting leads to better survival in patients with malignant airway obstruction.

BACKGROUND AND OBJECTIVE: Malignant airway obstruction (MAO), a common complication of patients with advanced lung cancer, causes debilitating dyspnoea and poor quality of life. Two common interventions used in the treatment of MAO include bronchoscopy with airway stenting and external beam radiotherapy (EBRT). Data are limited regarding their clinical effectiveness and overall effect on survival. METHODS: A retrospective chart review of patients treated with airway stenting and/or EBRT at the Johns Hopkins Hospital for MAO between July 2010 and January 2017 was reviewed. Demographics, performance status, cancer histology, therapeutic intervention and date of death were recorded. Survival was calculated using cox regression analysis. RESULTS: Of the 606 patients who were treated for MAO, 237 were identified as having MAO and included in the study. Sixty-eight patients underwent rigid bronchoscopy and stenting, 102 EBRT and 67 a combined approach. Patients who underwent stenting hand an increased hazard ratio (HR) of death in comparison to those who received combination therapy (HR: 2.12, 95% CI: 1.02, 4.39), while there was a trend towards significance in the EBRT alone group in comparison to the combination therapy group (HR: 1.62, 95% CI: 0.93, 2.83). CONCLUSION: In this retrospective analysis, combination therapy with stenting and EBRT led to better survival in comparison to stenting or EBRT alone. Prospective cohort trials are needed to confirm these results.

Management of Central Airway Obstruction: An American College of Chest Physicians Clinical Practice Guideline.

BACKGROUND: Central airway obstruction (CAO), seen in a variety of malignant and non-malignant airway disorders, is associated with a poor prognosis. The management of CAO is dependent on provider training and local resources, which may make the clinical approach and outcomes highly variable. We reviewed the current literature and provided evidence-based recommendations for the management of CAO. METHODS: A multidisciplinary expert panel developed key questions using the PICO (Patient, Intervention, Comparator, and Outcomes) format and conducted a systematic literature search using MEDLINE (PubMed) and the Cochrane Library. The panel screened references for inclusion and used vetted evaluation tools to assess the quality of included studies and extract data, and graded the level of evidence supporting each recommendation. A modified Delphi technique was used to reach consensus on recommendations. RESULTS: A total of 9,688 abstracts were reviewed, 150 full-text articles were assessed, and 31 studies were included in the analysis. One good practice statement and 10 graded recommendations were developed. The overall certainty of evidence was very low. CONCLUSIONS: Therapeutic bronchoscopy can improve the symptoms, quality of life, and survival of patients with malignant and non-malignant CAO. Multi-modality therapeutic options, including rigid bronchoscopy with general anesthesia, tumor/tissue debridement, ablation, dilation, and stent placement, should be utilized when appropriate. Therapeutic options and outcomes are dependent on the underlying etiology of CAO. A multidisciplinary approach and shared decision-making with the patient are strongly encouraged.

Neoadjuvant nivolumab or nivolumab plus LAG-3 inhibitor relatlimab in resectable esophageal/gastroesophageal junction cancer: a phase Ib trial and ctDNA analyses.

Gastroesophageal cancer dynamics and drivers of clinical responses with immune checkpoint inhibitors (ICI) remain poorly understood. Potential synergistic activity of dual programmed cell death protein 1 (PD-1) and lymphocyte-activation gene 3 (LAG-3) inhibition may help improve immunotherapy responses for these tumors. We report a phase Ib trial that evaluated neoadjuvant nivolumab (Arm A, n = 16) or nivolumab-relatlimab (Arm B, n = 16) in combination with chemoradiotherapy in 32 patients with resectable stage II/stage III gastroesophageal cancer together with an in-depth evaluation of pathological, molecular and functional immune responses. Primary endpoint was safety; the secondary endpoint was feasibility; exploratory endpoints included pathological complete (pCR) and major pathological response (MPR), recurrence-free survival (RFS) and overall survival (OS). The study met its primary safety endpoint in Arm A, although Arm B required modification to mitigate toxicity. pCR and MPR rates were 40% and 53.5% for Arm A and 21.4% and 57.1% for Arm B. Most common adverse events were fatigue, nausea, thrombocytopenia and dermatitis. Overall, 2-year RFS and OS rates were 72.5% and 82.6%, respectively. Higher baseline programmed cell death ligand 1 (PD-L1) and LAG-3 expression were associated with deeper pathological responses. Exploratory analyses of circulating tumor DNA (ctDNA) showed that patients with undetectable ctDNA post-ICI induction, preoperatively and postoperatively had a significantly longer RFS and OS; ctDNA clearance was reflective of neoantigen-specific T cell responses. Our findings provide insights into the safety profile of combined PD-1 and LAG-3 blockade in gastroesophageal cancer and highlight the potential of ctDNA analysis to dynamically assess systemic tumor burden during neoadjuvant ICI that may open a therapeutic window for future intervention. ClinicalTrials.gov registration: NCT03044613 .

Molecularly targeted agents as radiosensitizers in cancer therapy--focus on prostate cancer.

As our understanding of the molecular pathways driving tumorigenesis improves and more druggable targets are identified, we have witnessed a concomitant increase in the development and production of novel molecularly targeted agents. Radiotherapy is commonly used in the treatment of various malignancies with a prominent role in the care of prostate cancer patients, and efforts to improve the therapeutic ratio of radiation by technologic and pharmacologic means have led to important advances in cancer care. One promising approach is to combine molecularly targeted systemic agents with radiotherapy to improve tumor response rates and likelihood of durable control. This review first explores the limitations of preclinical studies as well as barriers to successful implementation of clinical trials with radiosensitizers. Special considerations related to and recommendations for the design of preclinical studies and clinical trials involving molecularly targeted agents combined with radiotherapy are provided. We then apply these concepts by reviewing a representative set of targeted therapies that show promise as radiosensitizers in the treatment of prostate cancer.

DAART: a deep learning platform for deeply accelerated adaptive radiation therapy for lung cancer.

Purpose: The study aimed to implement a novel, deeply accelerated adaptive radiation therapy (DAART) approach for lung cancer radiotherapy (RT). Lung cancer is the most common cause of cancer-related death, and RT is the preferred medically inoperable treatment for early stage non-small cell lung cancer (NSCLC). In the current lengthy workflow, it takes a median of four weeks from diagnosis to RT treatment, which can result in complete restaging and loss of local control with delay. We implemented the DAART approach, featuring a novel deepPERFECT system, to address unwanted delays between diagnosis and treatment initiation. Materials and methods: We developed a deepPERFECT to adapt the initial diagnostic imaging to the treatment setup to allow initial RT planning and verification. We used data from 15 patients with NSCLC treated with RT to train the model and test its performance. We conducted a virtual clinical trial to evaluate the treatment quality of the proposed DAART for lung cancer radiotherapy. Results: We found that deepPERFECT predicts planning CT with a mean high-intensity fidelity of 83 and 14 HU for the body and lungs, respectively. The shape of the body and lungs on the synthesized CT was highly conformal, with a dice similarity coefficient (DSC) of 0.91, 0.97, and Hausdorff distance (HD) of 7.9 mm, and 4.9 mm, respectively, compared with the planning CT scan. The tumor showed less conformality, which warrants acquisition of treatment Day1 CT and online adaptive RT. An initial plan was designed on synthesized CT and then adapted to treatment Day1 CT using the adapt to position (ATP) and adapt to shape (ATS) method. Non-inferior plan quality was achieved by the ATP scenario, while all ATS-adapted plans showed good plan quality. Conclusion: DAART reduces the common online ART (ART) treatment course by at least two weeks, resulting in a 50% shorter time to treatment to lower the chance of restaging and loss of local control.

Improving Quality Metrics in Radiation Oncology: Implementation of Pretreatment Peer Review for Stereotactic Body Radiation Therapy in Patients with Thoracic Cancer.

Purpose: Traditional peer reviews occur weekly, and can take place up to 1 week after the start of treatment. The American Society for Radiation Oncology peer-review white paper identified stereotactic body radiation therapy (SBRT) as a high priority for contour/plan review before the start of treatment, considering both the rapid-dose falloff and short treatment course. Yet, peer-review goals for SBRT must also balance physician time demands and the desire to avoid routine treatment delays that would occur in the setting of a 100% pretreatment (pre-Tx) review compliance requirement or prolonging the standard treatment planning timeline. Herein, we report on our pilot experience of a pre-Tx peer review of thoracic SBRT cases. Methods and Materials: From March 2020 to August 2021, patients undergoing thoracic SBRT were identified for pre-Tx review, and placed on a quality checklist. We implemented twice-weekly meetings for detailed pre-Tx review of organ-at-risk/target contours and dose constraints in the treatment planning system for SBRT cases. Our quality metric goal was to peer review ≥90% of SBRT cases before exceeding 25% of the dose delivered. We used a statistical process control chart with sigma limits (ie, standard deviations [SDs]) to access compliance rates with pre-Tx review implementation. Results: We identified 252 patients treated with SBRT to 294 lung nodules. When comparing pre-Tx review completion from initial rollout to full implementation, our rates improved from 19% to 79% (ie, from 1 sigma limit [SDs]) below to >2 sigma limits (SDs) above. Additionally, early completion of any form of contour/plan review (defined as any pre-Tx or standard review completed before exceeding 25% of the dose delivered) increased from 67% to 85% (March 2020-November 2020) to 76% to 94% (December 2020-August 2021). Conclusions: We successfully implemented a sustainable workflow for detailed pre-Tx contour/plan review for thoracic SBRT cases in the context of twice-weekly disease site-specific peer-review meetings. We reached our quality improvement objective to peer review ≥90% of SBRT cases before exceeding 25% of the dose delivered. This process was feasible to conduct in an integrated network of sites across our system.

Ablative radiation alone in stage I lung cancer produces an adaptive systemic immune response: insights from a prospective stud.

Stereotactic ablative body radiation (SABR) delivers high rates of local control in early-stage non-small cell lung cancer (NSCLC); however, systemic immune effects are poorly understood. Here, we evaluate the early pathologic and immunologic effects of SABR. Blood/core-needle tumor biopsies were collected from six patients with stage I NSCLC before and 5-7 days after SABR (48 Gy/4 or 50 Gy/5 fractions). Serial blood was collected up to 1-year post-SABR. We used immunohistochemistry to evaluate pathological changes, immune-cell populations (CD8, FoxP3), and PD-L1/PD-1 expression within the tumor. We evaluated T-cell receptor (TCR) profile changes in the tumor using TCR sequencing. We used the MANAFEST (Mutation-Associated Neoantigen Functional Expansion of Specific T-cells) assay to detect peripheral neoantigen-specific T-cell responses and dynamics. At a median follow-up of 40 months, 83% of patients (n=5) were alive without tumor progression. Early post-SABR biopsies showed viable tumor and similar distribution of immune-cell populations as compared with baseline samples. Core-needle samples proved insufficient to detect population-level TCR-repertoire changes. Functionally, neoantigen-specific T-cells were detected in the blood prior to SABR. A subset of these patients had a transient increase in the frequency of neoantigen-specific T-cells between 1 week and 3-6 months after SABR. SABR alone could induce a delayed, transient neoantigen-specific T-cell immunologic response in patients with stage I NSCLC.

Safety and clinical efficacy of immune checkpoint inhibition and stereotactic body radiotherapy in patients with spine metastasis.

OBJECTIVE: Immunotherapy, particularly immune checkpoint inhibitors (ICIs), has revolutionized the treatment of patients with many tumor histologies. Simultaneously, stereotactic body radiotherapy (SBRT) provides excellent local control (LC) and plays an important role in the management of spine metastasis. Promising preclinical work suggests the potential therapeutic benefit of combining SBRT with ICI therapy, but the safety profile of combined therapy is unclear. This study aimed to evaluate the toxicity profile associated with ICI in patients receiving SBRT and, secondarily, whether ICI administration sequence with respect to SBRT affects LC or overall survival (OS) outcomes. METHODS: The authors retrospectively reviewed patients with spine metastasis treated with SBRT at an academic center. Patients who received ICI at any point during their disease course were compared to those with the same primary tumor types who did not receive ICI by using Cox proportional hazards analyses. Primary outcomes were long-term sequelae, including radiation-induced spinal cord myelopathy, esophageal stricture, and bowel obstruction. Secondarily, models were created to evaluate OS and LC in the cohort. RESULTS: Two hundred forty patients who received SBRT to 299 spine metastases were included in this study. The most common primary tumor types were non-small cell lung cancer (n = 59 [24.6%]) and renal cell carcinoma (n = 55 [22.9%]). One hundred eight patients received at least 1 dose of ICI, with the most common regimen being single-agent anti-PD-1 (n = 80 [74.1%]), followed by combination CTLA-4/PD-1 inhibitors (n = 19 [17.6%]). Three patients experienced long-term radiation-induced sequelae: 2 had esophageal stricture and 1 had bowel obstruction. No patients developed radiation-induced myelopathy. There was no association between receipt of ICI and development of any of these adverse events (p > 0.9). Similarly, ICI was not significantly associated with either LC (p = 0.3) or OS (p = 0.6). In the entire cohort, patients who received ICI prior to beginning SBRT had worse median survival, but ICI sequence with respect to SBRT was not significantly prognostic of either LC (p > 0.3) or OS (p > 0.07); instead, baseline performance status was most predictive of OS (HR 1.38, 95% CI 1.07-1.78, p = 0.012). CONCLUSIONS: Treatment regimens that combine ICIs before, concurrent with, and after SBRT for spine metastases are safe, with minimal risk for increased rates of long-term toxicity.

The radiobiological P(+) index for pretreatment plan assessment with emphasis on four-dimensional radiotherapy modalities.

PURPOSE: Radiation treatment modalities will continue to emerge that promise better clinical outcomes albeit technologically challenging to implement. An important question facing the radiotherapy community then is the need to justify the added technological effort for the clinical return. Mobile tumor radiotherapy is a typical example, where 4D tumor tracking radiotherapy (4DTRT) has been proposed over the simpler conventional modality for better results. The modality choice per patient can depend on a wide variety of factors. In this work, we studied the complication-free tumor control probability (P(+)) index, which combines the physical complexity of the treatment plan with the radiobiological characteristics of the clinical case at hand and therefore found to be useful in evaluating different treatment techniques and estimating the expected clinical effectiveness of different radiation modalities. METHODS: 4DCT volumes of 18 previously treated lung cancer patients with tumor motion and size ranging from 2 mm to 15 mm and from 4 cc to 462 cc, respectively, were used. For each patient, 4D treatment plans were generated to extract the 4D dose distributions, which were subsequently used with clinically derived radiobiological parameters to compute the P(+) index per modality. RESULTS: The authors observed, on average, a statistically significant increase in P(+) of 3.4% ± 3.8% (p < 0.003) in favor of 4DTRT. There was high variability among the patients with a <0.5% up to 13.4% improvement in P(+). CONCLUSIONS: The observed variability in the improvement of the clinical effectiveness suggests that the relative benefit of tracking should be evaluated on a per patient basis. Most importantly, this variability could be effectively captured in the computed P(+). The index can thus be useful to discriminate and hence point out the need for a complex modality like 4DTRT over another. Besides tumor mobility, a wide range of other factors, e.g., size, location, fractionation, etc., can affect the relative benefits. Application of the P(+) objective is a simple and effective way to combine these factors in the evaluation of a treatment plan.

A method for deriving a 4D-interpolated balanced planning target for mobile tumor radiotherapy.

PURPOSE: Tumor control and normal tissue toxicity are strongly correlated to the tumor and normal tissue volumes receiving high prescribed dose levels in the course of radiotherapy. Planning target definition is, therefore, crucial to ensure favorable clinical outcomes. This is especially important for stereotactic body radiation therapy of lung cancers, characterized by high fractional doses and steep dose gradients. The shift in recent years from population-based to patient-specific treatment margins, as facilitated by the emergence of 4D medical imaging capabilities, is a major improvement. The commonly used motion-encompassing, or internal-target volume (ITV), target definition approach provides a high likelihood of coverage for the mobile tumor but inevitably exposes healthy tissue to high prescribed dose levels. The goal of this work was to generate an interpolated balanced planning target that takes into account both tumor coverage and normal tissue sparing from high prescribed dose levels, thereby improving on the ITV approach. METHODS: For each 4DCT dataset, 4D deformable image registration was used to derive two bounding targets, namely, a 4D-intersection and a 4D-composite target which minimized normal tissue exposure to high prescribed dose levels and maximized tumor coverage, respectively. Through definition of an "effective overlap volume histogram" the authors derived an "interpolated balanced planning target" intended to balance normal tissue sparing from prescribed doses with tumor coverage. To demonstrate the dosimetric efficacy of the interpolated balanced planning target, the authors performed 4D treatment planning based on deformable image registration of 4D-CT data for five previously treated lung cancer patients. Two 4D plans were generated per patient, one based on the interpolated balanced planning target and the other based on the conventional ITV target. Plans were compared for tumor coverage and the degree of normal tissue sparing resulting from the new approach was quantified. RESULTS: Analysis of the 4D dose distributions from all five patients showed that while achieving tumor coverage comparable to the ITV approach, the new planning target definition resulted in reductions of lung V(10), V(20), and V(30) of 6.3% ± 1.7%, 10.6% ± 3.9%, and 12.9% ± 5.5%, respectively, as well as reductions in mean lung dose, mean dose to the GTV-ring and mean heart dose of 8.8% ± 2.5%, 7.2% ± 2.5%, and 10.6% ± 3.6%, respectively. CONCLUSIONS: The authors have developed a simple and systematic approach to generate a 4D-interpolated balanced planning target volume that implicitly incorporates the dynamics of respiratory-organ motion without requiring 4D-dose computation or optimization. Preliminary results based on 4D-CT data of five previously treated lung patients showed that this new planning target approach may improve normal tissue sparing without sacrificing tumor coverage.

A digital physician peer to automatically detect erroneous prescriptions in radiotherapy.

Appropriate dosing of radiation is crucial to patient safety in radiotherapy. Current quality assurance depends heavily on a physician peer-review process, which includes a review of the treatment plan's dose and fractionation. Potentially, physicians may not identify errors during this manual peer review due to time constraints and caseload. A novel prescription anomaly detection algorithm is designed that utilizes historical data from the past to predict anomalous cases. Such a tool can serve as an electronic peer who will assist the peer-review process providing extra safety to the patients. In our primary model, we create two dissimilarity metrics, R and F. R defining how far a new patient's prescription is from historical prescriptions. F represents how far away a patient's feature set is from that of the group with an identical or similar prescription. We flag prescription if either metric is greater than specific optimized cut-off values. We use thoracic cancer patients (n = 2504) as an example and extracted seven features. Our testing set f1 score is between 73%-94% for different treatment technique groups. We also independently validate our results by conducting a mock peer review with three thoracic specialists. Our model has a lower type II error rate compared to the manual peer-review by physicians.

Evaluating Proton Dose and Associated Range Uncertainty Using Daily Cone-Beam CT.

Purpose: This study aimed to quantitatively evaluate the range uncertainties that arise from daily cone-beam CT (CBCT) images for proton dose calculation compared to CT using a measurement-based technique. Methods: For head and thorax phantoms, wedge-shaped intensity-modulated proton therapy (IMPT) treatment plans were created such that the gradient of the wedge intersected and was measured with a 2D ion chamber array. The measured 2D dose distributions were compared with 2D dose planes extracted from the dose distributions using the IMPT plan calculated on CT and CBCT. Treatment plans of a thymoma cancer patient treated with breath-hold (BH) IMPT were recalculated on 28 CBCTs and 9 CTs, and the resulting dose distributions were compared. Results: The range uncertainties for the head phantom were determined to be 1.2% with CBCT, compared to 0.5% for CT, whereas the range uncertainties for the thorax phantom were 2.1% with CBCT, compared to 0.8% for CT. The doses calculated on CBCT and CT were similar with similar anatomy changes. For the thymoma patient, the primary source of anatomy change was the BH uncertainty, which could be up to 8 mm in the superior-inferior (SI) direction. Conclusion: We developed a measurement-based range uncertainty evaluation method with high sensitivity and used it to validate the accuracy of CBCT-based range and dose calculation. Our study demonstrated that the CBCT-based dose calculation could be used for daily dose validation in selected proton patients.

An Oncology Urgent Care Clinic for the Management of Immune-Related Adverse Events: A Descriptive Analysis.

Introduction: With the increasing use of immune checkpoint inhibitors (ICI) for cancer, there is a growing burden on the healthcare system to provide care for the toxicities associated with these agents. Herein, we aim to identify and describe the distribution of encounters seen in an urgent care setting for immune-related adverse events (irAEs) and the clinical outcomes from irAE management. Methods: Patient demographics, disease characteristics, and treatment data were collected retrospectively from encounters at an oncology Urgent Care Clinic (UCC) from a single tertiary center for upper aerodigestive malignancies from 1 July 2018 to 30 June 2019. Data were summarized using descriptive statistics with odds ratios for associations between patient features and hospitalization after UCC evaluation. Results: We identified 494 encounters from 289 individual patients over the study period. A history of ICI therapy was noted in 34% (n = 170/494) of encounters and 29 encounters (29/170, 17%) were confirmed and treated as irAEs. For those treated for irAEs, the majority (n = 19/29; 66%) were discharged home. Having an irAE was associated with an increased risk of hospitalization compared to non-irAEs (OR 5.66; 95% CI 2.15−14.89; p < 0.001). Conclusion: In this single institution experience, the majority of UCC encounters for confirmed irAEs were safely managed within the UCC. In ICI-treated patients, having an irAE was associated with an increased risk of hospitalization versus non-irAEs.