Omission of adjuvant radiotherapy in low-risk elderly males with breast cancer

PURPOSE

Randomized clinical trials demonstrate that lumpectomy + hormone therapy (HT) without radiation therapy (RT) yields equivalent survival and acceptable local-regional outcomes in elderly women with early-stage, node-negative, hormone-receptor positive (HR +) breast cancer. Whether these data apply to men with the same inclusion criteria remains unknown.

METHODS

The National Cancer Database was queried for male patients ≥ 65 years with pathologic T1-2N0 (≤ 3 cm) HR + breast cancer treated with breast-conserving surgery with negative margins from 2004 to 2019. Adjuvant treatment was classified as HT alone, RT alone, or HT + RT. Male patients were matched with female patients for OS comparison. Survival analysis was performed using Cox regression and Kaplan - Meier method. Inverse probability of treatment weighting (IPTW) was applied to adjust for confounding.

RESULTS

A total of 523 patients met the inclusion criteria, with 24.4% receiving HT, 16.3% receiving RT, and 59.2% receiving HT + RT. The median follow-up was 6.9 years (IQR: 5.0-9.4 years). IPTW-adjusted 5-yr OS rates in the HT, RT, and HT + RT cohorts were 84.0% (95% CI 77.1-91.5%), 81.1% (95% CI 71.1-92.5%), and 93.0% (95% CI 90.0-96.2%), respectively. On IPTW-adjusted MVA, relative to HT, receipt of HT + RT was associated with improvements in OS (HR: 0.641; p = 0.042). RT alone was not associated with improved OS (HR: 1.264; p = 0.420).

CONCLUSION

Among men ≥ 65 years old with T1-2N0 HR + breast cancer, RT alone did not confer an OS benefit over HT alone. Combination of RT + HT demonstrated significant improvements in OS. De-escalation of treatment through omission of either RT or HT at this point should be done with caution.

Perception and Utilization of Cannabinoids in Patients Undergoing Radiation Treatment: Our Patients Are Curious

PURPOSE

Limited studies have described the utilization of cannabinoids among patients with cancer. This survey study aimed to characterize utilization patterns and perceptions of cannabinoid use for treatment-related side effects among patients receiving radiation treatment.

METHODS AND MATERIALS

This was an anonymous survey study of patients who were undergoing or recently completed radiation treatment at a comprehensive cancer center. Data on cannabinoid use during cancer treatment, reasons for the use of cannabinoids, perceived effects of cannabinoids, and formulations of usage were collected and summarized using descriptive statistics.

RESULTS

Of the 431 respondents, 111 (25.8%) patients reported cannabinoid use since their cancer diagnosis. Among the cannabinoid users, a majority (73.9%) experienced improvement in symptoms; 38.7% had better relief of cancer-treatment symptoms from cannabinoids in comparison to their prescription medications, and 16.2% lowered the amount of prescription pain medications needed after using cannabinoids. Cannabinoids appeared to be most effective in helping patients manage sleep (76.6%) and anxiety (72.1%). When asked about whether physicians should be discussing cannabinoid use, 45.1% of cannabinoid users wanted to speak with their doctors regarding its utilization. For patients who did not report cannabinoid use, a large majority (83.1%) never had discussions with their doctors regarding its utilization as part of their cancer care, and 34.8% wanted to learn more about cannabinoids from their doctors.

CONCLUSIONS

About 1 in 4 patients with cancer reported cannabinoid use to assist in symptom control. A majority had subjective alleviation of treatment-related symptoms from cannabinoid use. Regardless of cannabinoid use, a sizable percentage of patients never had any discussions about cannabinoids with their oncologists, with some expressing interest in learning more. Guidelines are needed to assist radiation oncologists on how cannabinoids may play a role in caring for patients.

Current Status and Future Directions of Image-Guided Adaptive Brachytherapy for Locally Advanced Cervical Cancer

PURPOSE

The standard of care for patients with locally advanced cervical cancer is definitive chemoradiation followed by a brachytherapy boost. This review describes the current status and future directions of image-guided adaptive brachytherapy for locally advanced cervical cancer.

METHODS

A systematic search of the PubMed and Clinicaltrials.gov databases was performed, focusing on studies published within the last 10 years. The search queried "cervical cancer [AND] image-guided brachytherapy [OR] magnetic resonance imaging (MRI) [OR] adaptive brachytherapy".

DISCUSSION

The retroEMBRACE and EMBRACE-I trials have established the use of MRI as the standard imaging modality for brachytherapy application and planning. Quantitative imaging and radiomics have the potential to improve outcomes, with three ongoing prospective studies examining the use of radiomics to further risk-stratify patients and personalize brachytherapy. Another active area of investigation includes utilizing the superior soft tissue contrast provided by MRI to increase the dose per fraction and decrease the number of fractions needed for brachytherapy, with several retrospective studies demonstrating the safety and feasibility of three-fraction courses. For developing countries with limited access to MRI, trans-rectal ultrasound (TRUS) appears to be an effective alternative, with several retrospective studies demonstrating improved target delineation with the use of TRUS in conjunction with CT guidance.

CONCLUSIONS

Further investigation is needed to continue improving outcomes for patients with locally advanced cervical cancer treated with image-guided brachytherapy.

Stereotactic Radiosurgery in the Management of Brain Metastases: A Case-Based Radiosurgery Society Practice Guideline

Purpose

Brain metastases are common among adult patients with solid malignancies and are increasingly being treated with stereotactic radiosurgery (SRS). As more patients with brain metastases are becoming eligible for SRS, there is a need for practical review of patient selection and treatment considerations.

Methods and Materials

Two patient cases were identified to use as the foundation for a discussion of a wide and representative range of management principles: (A) SRS alone for 5 to 15 lesions and (B) a large single metastasis to be treated with pre- or postoperative SRS. Patient selection, fractionation, prescription dose, treatment technique, and dose constraints are discussed. Literature relevant to these cases is summarized to provide a framework for treatment of similar patients.

Results

Treatment of brain metastases with SRS requires many considerations including optimal patient selection, fractionation selection, and plan optimization.

Conclusions

Case-based practice guidelines developed by the Radiosurgery Society provide a practical guide to the common scenarios noted above affecting patients with metastatic brain tumors.

Stereotactic Body Radiation Therapy: A Radiosurgery Society Guide to the Treatment of Localized Prostate Cancer Illustrated by Challenging Cases

Traditionally, external beam radiotherapy (EBRT) for localized prostate cancer (PCa) involved lengthy courses with low daily doses. However, advancements in radiation delivery and a better understanding of prostate radiobiology have enabled the development of shorter courses of EBRT. Ultrahypofractionated radiotherapy, administering doses greater than 5 Gy per fraction, is now considered a standard of care regimen for localized PCa, particularly for intermediate-risk disease. Stereotactic body radiotherapy (SBRT), a specific type of ultrahypofractionated radiotherapy employing advanced planning, imaging, and treatment technology to deliver in five or fewer fractions, is gaining prominence as a cost-effective, convenient, and safe alternative to longer radiotherapy courses. It is crucial to address practical considerations related to patient selection, fractionation scheme, target delineation, and planning objectives. This is especially important in challenging clinical situations where clear evidence for guidance may be lacking. The Radiosurgery Society endorses this case-based guide with the aim of providing a practical framework for delivering SBRT to the intact prostate, exemplified by two case studies. The article will explore common SBRT dose/fractionation schemes and dose constraints for organs-at-risk. Additionally, it will review existing evidence and expert opinions on topics such as SBRT dose escalation, the use of rectal spacers, the role of androgen deprivation therapy in the context of SBRT, SBRT in special patient populations (e.g., high-risk disease, large prostate, high baseline urinary symptom burdens, and inflammatory bowel disease), as well as new imaging-guidance techniques like Magnetic Resonance Imaging for SBRT delivery.

Explainable Artificial Intelligence to Identify Dosimetric Predictors of Toxicity in Patients with Locally Advanced Non-Small Cell Lung Cancer: A Secondary Analysis of RTOG 0617

PURPOSE

Dosimetric predictors of toxicity in patients treated with definitive chemoradiation for locally advanced non-small cell lung cancer are often identified through trial and error. This study used machine learning (ML) and explainable artificial intelligence to empirically characterize dosimetric predictors of toxicity in patients treated as part of a prospective clinical trial.

METHODS AND MATERIALS

A secondary analysis of the Radiation Therapy Oncology Group (RTOG) 0617 trial was performed. Multiple ML models were trained to predict grade ≥3 pulmonary, cardiac, and esophageal toxicities using clinical and dosimetric features. Model performance was evaluated using the area under the curve (AUC). The best performing model for each toxicity was explained using the Shapley Additive Explanation (SHAP) framework; SHAP values were used to identify relevant dosimetric thresholds and were converted to odds ratios (ORs) with confidence intervals (CIs) generated using bootstrapping to obtain quantitative measures of risk. Thresholds were validated using logistic regression.

RESULTS

The best-performing models for pulmonary, cardiac, and esophageal toxicities, outperforming logistic regression, were extreme gradient boosting (AUC, 0.739), random forest (AUC, 0.706), and naive Bayes (AUC, 0.721), respectively. For pulmonary toxicity, thresholds of a mean dose >18 Gy (OR, 2.467; 95% CI, 1.049-5.800; P = .038) and lung volume receiving ≥20 Gy (V20) > 37% (OR, 2.722; 95% CI, 1.034-7.163; P = .043) were identified. For esophageal toxicity, thresholds of a mean dose >34 Gy (OR, 4.006; 95% CI, 2.183-7.354; P < .001) and V20 > 37% (OR, 3.725; 95% CI, 1.308-10.603; P = .014) were identified. No significant thresholds were identified for cardiac toxicity.

CONCLUSIONS

In this data set, ML approaches validated known dosimetric thresholds and outperformed logistic regression at predicting toxicity. Furthermore, using explainable artificial intelligence, clinically useful dosimetric thresholds might be identified and subsequently externally validated.

Stereotactic Body Radiation Therapy for Oligoprogressive and Oligorecurrent Non-Small-Cell Lung Cancer

BACKGROUND AND PURPOSE

The role of stereotactic body radiation therapy (SBRT) in oligoprogressive non-small-cell lung cancer (NSCLC) is controversial. We evaluated whether SBRT in a subset of patients with oligoprogressive or oligorecurrent NSCLC offers a durable response, obviating the need to change systemic therapy.

METHODS

A retrospective analysis of 168 NSCLC patients who underwent SBRT for oligoprogressive or oligorecurrent disease was performed. Oligoprogression was defined as progression in ≤5 lesions during or after systemic therapy following an initial complete or partial response. Oligorecurrence was defined as progression while off systemic therapy. Progression-free survival (PFS), overall survival (OS) and time to next treatment or death (TNT-D) were estimated.

RESULTS

Median age was 68 years. Sixty-seven percent of patients were on systemic therapy at the time of progression. Progression at the primary site was present in 31% of the patients. The number of sites of metastatic progression was 0 to 2 in 76% and 3 to 5 in 24% of the patients. Two-year OS and PFS were 56% (95%CI 46%-64%) and 14% (95%CI 8%-21%), respectively. Median TNT-D was 9 months (95%CI 6-11). No grade 4 or 5 toxicity was seen. In multivariable analysis, patients with 3 to 5 sites of metastatic progression had worse OS (HR 2.6, 95%CI 1.5-4.3, P < .001) and shorter TNT-D (HR 1.7, 95%CI 1.1-2.5, P = .01) than those with 0 to 2 sites.

CONCLUSION

SBRT is a safe and viable treatment option for oligoprogressive and oligorecurrent NSCLC. Patients with 0 to 2 sites had better OS and longer TNT-D compared to those with 3 to 5 lesions.

Stereotactic Body Radiation Therapy for Gynecologic Malignancies: A Case-Based Radiosurgery Society Practice Review

PURPOSE

The use of stereotactic body radiation therapy (SBRT) for gynecologic malignancies is controversial. We discuss certain circumstances when highly precise SBRT may be a useful tool to consider in the management of selected patients.

METHODS AND MATERIALS

Case selection included the following scenarios, the first 2 with palliative intent, para-aortic nodal oligorecurrence of ovarian cancer, pelvic sidewall oligorecurrence of cervical cancer, and inoperable endometrial cancer boost after intensity modulated radiation to the pelvis treated with curative intent. Patient characteristics, fractionation, prescription dose, treatment technique, and dose constraints were discussed. Relevant literature to these cases was summarized to provide a framework for treatment of similar patients.

RESULTS

Treatment of gynecologic malignancies with SBRT requires many considerations, including treatment intent, optimal patient selection, fractionation selection, tumor localization, and plan optimization. Although other treatment paradigms including conventionally fractionated radiation therapy and brachytherapy remain the standard-of-care for definitive treatment of gynecologic malignancies, SBRT may have a role in palliative cases or those where high doses are not required due to the unacceptable toxicity that may occur with SBRT.

CONCLUSIONS

A case-based practice review was developed by the Radiosurgery Society to provide a practical guide to the common scenarios noted above affecting patients with gynecologic malignancies.

A practical guide to hybrid interstitial/intracavitary brachytherapy for locally-advanced cervical cancer

PURPOSE

In select cases of locally advanced cervical cancer, a hybrid brachytherapy (HBT) approach consisting of a combined intracavitary (IC)/insterstitial (IS) implant can yield improved target coverage and/or decreased organ at risk dose compared to IC techniques while limiting invasiveness compared to IS techniques.

METHODS AND MATERIALS

The technique involves placement of transvaginal and/or perineal needles in addition to the tandem and ring/ovoids using either a specialized applicator or free-hand placement. Following applicator and needle placement, brachytherapy may then be planned using principles similar to IC or IS techniques. During treatment planning, it can be helpful to obtain both MRI and CT imaging, as plastic MRI-compatible needles do not show up well on MRI.

RESULTS

In patients where acceptable target coverage cannot be achieved using IC alone or doses to nearby OAR are too high, HBT should be evaluated. HBT can improve both dose to target and OAR while sparing patients the morbidity of perineal template-based interstitial brachytherapy. Specific scenarios where HBT may be preferred include bulky residual primary tumor especially with poor response to EBRT, extension into the lateral parametrium, vaginal extension of tumor, and an asymmetric target. Use of HBT can typically permit extension of dose coverage by an additional 1-2 cm beyond what can be achieved with an IC alone technique.

CONCLUSION

HBT allows for improved therapeutic ratio by improving target volume coverage and/or lowering doses to OARs. Brachytherapists should be trained on the practical aspects of administering HBT to be able to offer a less invasive and impactful treatment option when appropriate.

Modern Radiation for Hematologic Stem Cell Transplantation: Total Marrow and Lymphoid Irradiation or Intensity-Modulated Radiation Therapy Total Body Irradiation

The development of large-field intensity-modulated radiation therapy (IMRT) has enabled the implementation of total marrow irradiation (TMI), total marrow and lymphoid irradiation (TMLI), and IMRT total body irradiation (TBI). IMRT TBI limits doses to organs at risk, primarily the lungs and in some cases the kidneys and lenses, which may mitigate complications. TMI/TMLI allows for dose escalation above TBI radiation therapy doses to malignant sites while still sparing organs at risk. Although still sparingly used, these techniques have established feasibility and demonstrated promise in reducing the adverse effects of TBI while maintaining and potentially improving survival outcomes.

Implications of updated staging system for p16+ oropharyngeal squamous cell carcinoma: Is valuable prognostic information being omitted?

BACKGROUND

This study characterized whether the updated AJCC 8th edition nodal staging system for p16+ oropharyngeal squamous cell carcinoma (OPSCC) resulted in the loss of prognostic value.

METHODS

The NCDB was queried for patients with node-positive p16+ OPSCC. The prognostic impact of nodal size, nodal quantity, nodal laterality, and extracapsular extension (ECE) on overall survival (OS) was assessed.

RESULTS

In the clinical cohort, inferior 5-year OS was observed in patients with more than one positive lymph node (p < 0.001; 82% vs. 86%), ECE (p < 0.001; 82% vs. 75%), or nodal size >6 cm (p < 0.001; 66% vs. 82%). In the pathologic cohort, inferior 5-year OS was observed in patients with > four positive lymph nodes (p < 0.001; 76% vs. 90%), ECE (p < 0.001; 83% vs. 92%), or largest nodal size >6 cm (p < 0.001; 81% vs. 89%).

CONCLUSIONS

Simplifications in the current p16+ OPSCC staging system led to loss of prognostic information in nodal staging.

Clinical Applications of Magnetic Resonance-Guided Radiotherapy: A Narrative Review

Magnetic resonance-guided radiotherapy (MRgRT) represents a promising new image guidance technology for radiation treatment delivery combining an onboard MRI scanner with radiation delivery technology. By enabling real-time low-field or high-field MRI acquisition, it facilitates improved soft tissue delineation, adaptive treatment, and motion management. Now that MRgRT has been available for nearly a decade, research has shown the technology can be used to effectively shrink treatment margins to either decrease toxicity (in breast, prostate cancer, and pancreatic cancer) or facilitate dose-escalation and improved oncologic outcomes (in pancreatic and liver cancer), as well as enabling indications that require clear soft tissue delineation and gating (lung and cardiac ablation). In doing so, the use of MRgRT has the potential to significantly improve the outcomes and quality of life of the patients it treats. The present narrative review aims to describe the rationale for MRgRT, the current and forthcoming state of technology, existing studies, and future directions for the advancement of MRgRT, including associated challenges.

Evaluation of repeatability and reproducibility of radiomic features produced by the fan-beam KV-CT on a novel ring gantry-based PET/CT linear accelerator

BACKGROUND

The RefleXion^® X1 is a novel radiotherapy delivery system on a ring gantry equipped with fan-beam kV-CT and PET imaging subsystems. The day-to-day scanning variability of radiomics features must be evaluated before any attempt to utilize radiomics features PURPOSE: This study aims to characterize the repeatability and reproducibility of radiomic features produced by the RefleXion^® X1 kV-CT.

MATERIALS AND METHODS

The Credence Cartridge Radiomics (CCR) phantom includes six cartridges of varied materials. It was scanned ten times on the RefleXion X1 kVCT imaging subsystem over a three-month period using the two most frequently used scanning protocols (BMS and BMF). Fifty-five radiomic features were extracted for each ROI on each CT scan and analyzed using LifeX software. The coefficient of variation (COV) was computed to evaluate the repeatability. Intraclass correlation coefficient (ICC) and concordance correlation coefficient (CCC) were used to evaluate the repeatability and reproducibility of the scanned images using 0.9 as the threshold. This process is repeated on a GE PET-CT scanner using several built-in protocols as a comparison.

RESULTS

On average, 87% of the features on both scan protocols on the RefleXion X1 kVCT imaging subsystem can be considered repeatable as they met COV < 10% criteria. On GE PET-CT, this number is similar at 86%. When we tighten the criteria to COV<5%, the RefleXion X1 kVCT imaging subsystem showed much better repeatability with 81% of features on average whereas GE PET-CT showed only 73.5% on average. About 91% and 89% of the features with ICC>0.9 respectively for BMS and BMF protocols on RefleXion X1. On the other hand, the percentage of features with ICC>0.9 on GE PET-CT ranges from 67% to 82%. The RefleXion X1 kVCT imaging subsystem showed excellent intra-scanner reproducibility between the scanning protocols much better than the GE PET CT scanner. For the inter-scanner reproducibility, the percentage of features with CCC>0.9 ranged from 49% to 80%. between X1 and GE PET-CT scanning protocols.

CONCLUSIONS

Clinically useful CT radiomic features produced by the RefleXion X1 kVCT imaging subsystem are reproducible and stable over time, demonstrating its utility as a quantitative imaging platform. This article is protected by copyright. All rights reserved.

Long-Term Follow-Up of Bridging Therapies Prior to CAR T-Cell Therapy for Relapsed/Refractory Large B Cell Lymphoma

Background: Bridging therapy (BT) with systemic therapy (ST), radiation therapy (RT), or combined-modality therapy (CMT) is increasingly being utilized prior to chimeric antigen receptor (CAR) T-cell therapy for large B-cell lymphoma (LBCL). We report the long-term outcomes of the patients who received commercial CAR T-cell therapy with or without BT. Methods: The patients with LBCL who underwent infusion of a commercial CD19 CAR T product were eligible. The radiation was stratified as comprehensive or focal. The efficacy outcomes and toxicity were analyzed. Results: In total, 156 patients were included and, of them, 52.5% of the patients received BT. The median progression-free survival (PFS) was 0.65 years in the BT cohort compared to 1.45 years in the non-BT cohort. The median overall survival (OS) was 3.16 years in the BT cohort and was not reached in the non-BT cohort. The patients who received comprehensive radiation (versus focal) had significantly improved PFS and OS, achieving a 1-year PFS of 100% vs. 9.1% and 1-year OS of 100% vs. 45.5%. There was no difference in the severe toxicity between any of the nonbridging or BT cohorts. Conclusions: BT did not appear to compromise outcomes with respect to response rates, disease control, survival, and toxicity. The patients with limited disease treated with RT had favorable outcomes.

Autologous Stem Cell Transplantation with Intensity Modulated Total Body Irradiation Conditioning for Systemic Sclerosis

BACKGROUND

Autologous stem cell transplantation (HSCT) using myeloablative total body irradiation (TBI) and anti-thymocyte globulin (ATG) as a conditioning regimen has become a standard treatment option for certain patients with systemic sclerosis (SSc). Normal organs are more radiosensitive and prone to compromised function in SSc, and therefore lungs and kidneys require dose reduction. We evaluated the role of intensity modulated radiation therapy (IMRT) TBI compared to standard anteroposterior (AP)/posteroanterior (PA) TBI technique.

MATERIALS/METHODS

Patients with SSc who underwent HSCT with TBI between 2017 and 2022 were eligible. All patients underwent conditioning with equine ATG, cyclophosphamide 120 mg/kg, and IMRT TBI to a total dose of 800 cGy in 200 cGy fractions. Patients were replanned using an AP/PA technique for dosimetric comparison. Patients were evaluated for outcomes including event-free survival (EFS), overall survival (OS), disease-modifying antirheumatic drug-free survival (DMARD-FS), and treatment related mortality (TRM).

RESULTS

14 patients were eligible for our analysis. Median follow-up was 34.6 months (1.0-51.7 months). There was one case of TRM secondary to respiratory failure. The 24-month OS, EFS, and DMARD-FS estimates were 92.9%, 74.3%, and 70.0%, respectively. Three patients experienced adverse events, which included respiratory failure (n=1), renal failure (n=1), and death (n=1). Five patients subsequently initiated DMARDs, but three did so due to worsening skin symptoms without other major organ dysfunction. On dosimetric analysis, the mean dose to the planning target volume (PTV) was significantly higher on the IMRT compared to the AP/PA plans (809.4 cGy versus 728.5 cGy, p<0.001). The mean dose to the lungs (239.5 cGy versus 443.9 cGy, p<0.001) and kidneys (204.9cGy versus 281.2 cGy, p<0.001) was significantly lower.

CONCLUSIONS

Use of IMRT TBI as part of the conditioning regimen for HSCT for SSc yields improved dosimetry with efficacy and toxicity outcomes comparable with published data.

Biology-Guided Radiation Therapy

Biology-guided radiation therapy is an emerging field whereby delivery of external beam radiotherapy incorporates biological/molecular imaging to inform radiation treatment. At present, there is evidence for the use of functional imaging such as PET to evaluate treatment response in patients both during and after radiation treatment as well as to provide a method of adapting or selecting patient-specific treatments. Examples in thoracic, gastrointestinal, and hematologic malignancies are provided. Improvements in PET metrics, thresholds, and novel radiotracers will further move this novel field forward.

Integration of artificial intelligence in lung cancer: Rise of the machine

The goal of oncology is to provide the longest possible survival outcomes with the therapeutics that are currently available without sacrificing patients' quality of life. In lung cancer, several data points over a patient's diagnostic and treatment course are relevant to optimizing outcomes in the form of precision medicine, and artificial intelligence (AI) provides the opportunity to use available data from molecular information to radiomics, in combination with patient and tumor characteristics, to help clinicians provide individualized care. In doing so, AI can help create models to identify cancer early in diagnosis and deliver tailored therapy on the basis of available information, both at the time of diagnosis and in real time as they are undergoing treatment. The purpose of this review is to summarize the current literature in AI specific to lung cancer and how it applies to the multidisciplinary team taking care of these complex patients.

Stereotactic body radiation therapy to the kidney for metastatic renal cell carcinoma: A narrative review of an emerging concept

This narrative review provides a historical overview of cytoreductive nephrectomy for metastatic renal cell carcinoma (mRCC) and examines the safety and therapeutic potential of cytoreductive stereotactic body radiation therapy (SBRT) for mRCC in the modern immunotherapy era. In the last five years, the introduction of immune checkpoint inhibitors for the treatment of mRCC has improved outcomes for patients. This has brought forth new exploration of the role of CN in combination with immunotherapy. Early retrospective evidence suggests that there may be a benefit of deferred CN after immunotherapy (IOT) for de novo mRCC patients. However, there has also been concern regarding the feasibility of surgery after IOT due to inflammation. SBRT may be an appropriate alternative in these circumstances. Since 1999, cytoreductive SBRT has been used for inoperable primary RCC. Several prospective and retrospective studies treating the kidney tumor for localized RCC have shown that this technique is safe and produces favorable and durable local control. SBRT has also exhibited similar effectiveness to CN, while providing additional benefits including noninvasiveness and the ability to treat tumors that can't be treated with nephrectomy or ablation due to size or location. Furthermore, SBRT confers immunostimulatory effects, which are hypothesized to work synergistically with immunotherapy. Clinicians should consider SBRT a safe and reliable alternative to CN for RCC patients. Ongoing studies are exploring the utility of SBRT for treatment of the primary tumor in mRCC patients receiving standard of care immunotherapy.

Patterns of Care for Patients With Locally Advanced Rectal Cancer Treated with Total Neoadjuvant Therapy at Predominately Academic Centers between 2016-2020: An NCDB Analysis

Total neoadjuvant therapy (TNT) has emerged as the preferred approach for locally advanced rectal cancer (LARC), defined as T3/4 or any T with N+ disease. Our objective was to (1) determine the proportion of patients with LARC receiving TNT over time, (2) determine the most common method in which TNT is being delivered, and (3) determine what factors are associated with a greater likelihood of receiving TNT in the United States. Retrospective data was obtained from the National Cancer Database (NCDB) for patients diagnosed with rectal cancer between 2016 and 2020. Patients were excluded if they had M1 disease, T1-2 N0 disease, incomplete staging information, nonadenocarcinoma histology, received RT to a nonrectum site, or received a nondefinitive RT dose. Data were analyzed using linear regression, χ² test, and binary logistic regression. Of the 26,375 patients included, most patients were treated at an academic facility (94.6%). Five thousand three (19.0%) patients received TNT, and 21,372 (81.0%) patients did not receive TNT. The proportion of patients receiving TNT increased significantly over time, from 6.1% in 2016 to 34.6% in 2020 (slope = 7.36, 95% CI 4.58-10.15, R² = 0.96, P = .040). The most common TNT regimen was multiagent chemotherapy followed by long-course chemoradiation (73.2% of cases from 2016-2020). There was a significant increase in utilization of short-course RT as part of TNT from 2.8% in 2016 to 13.7% in 2020 (slope = 2.74, 95% CI 0.37-5.11, R² = 0.82, P = .035). Factors associated with a lower likelihood of TNT usage included age >65, female gender, Black race, and T3 N0 disease. TNT use in the United States has increased significantly from 2016-2020, with approximately 34.6% of patients with LARC receiving TNT in 2020. The observed trend appears to be in line with the recent National Comprehensive Cancer Network guidelines recommending TNT as the preferred approach.

Prognostic Role of Biologically Active Volume of Disease in Patients With Metastatic Lung Adenocarcinoma

BACKGROUND

Number of metastatic sites can identify patient populations with non-small cell lung cancer (NSCLC) that benefit from aggressive therapy. Total volume of disease is also relevant. We evaluated the prognostic impact of biologically active volume of disease (BaVD) on patients with metastatic lung adenocarcinoma.

MATERIALS AND METHODS

Positron emission tomography/computerized tomography (PET/CT) scans from patients with newly diagnosed lung adenocarcinoma prior to starting any therapy were identified. SUV thresholds of 3 and 4 were used to auto-contour all FDG avid areas. Kaplan-Meier analysis and Cox regression were performed to examine influence on OS.

RESULTS

One hundred forty-eight patients were included in the analysis. The median BaVD when using an SUV threshold of 3 was 122.8 mL. The median BaVD when using an SUV threshold of 4 was 46.2 mL When stratified by median BaVD using an SUV of 3, median OS was higher for patients with <=122.8 mL (2.12 years) compared to patients with >122.8 mL (1.46 years) (log-rank P = .001). Similarly, when stratified by median BaVD using an SUV of 4, median OS was higher for patients with <=46.2 mL (1.91 years; 95% CI: 1.65-3.22 years) compared to patients with >46.2 mL (1.48 years; 95% CI: 1.07-1.80 years) (log-rank P = .007). On multivariable analysis, BaVD was significantly associated with OS when using an SUV threshold of 3 (HR: 20.169, P < .001) and 4 (HR: 4.117, P < .001).

CONCLUSION

BaVD is an important prognostic factor in metastatic lung adenocarcinoma and may aid identification of patients with limited disease who may be candidates for more aggressive therapies.

Volumetric modulated arc therapy based total marrow and lymphoid irradiation: Workflow and clinical experience

Background

The aim of this study is to report historical treatment planning experience at our institution for patients receiving total marrow and lymphatic irradiation (TMLI) using volumetric modulated arc therapy (VMAT) as part of the conditioning regimen prior to hematopoietic stem cell transplant.

Methods

We identified a total of fifteen patients with VMAT TMLI, ten with a prescription dose of 20 Gy (targeting the skeletal bones, lymph nodes, spleen, and spinal canal, with 12 Gy to the brain and liver) and five with a prescription dose of 12-16 Gy (targeting the skeletal bones, lymph nodes, spleen, and spinal canal). Representative dosimetric parameters including total treatment time, mean and median dose, D80, and D10 (dose covering 80% and 10% of the structure volume, respectively) for targets and normal organs were extracted and compared to historical patients treated with helical tomotherapy.

Results

The median treatment time for the first and subsequent fractions was 1.5 and 1.1 hours, respectively. All the target volumes had a mean dose greater than the prescribed dose except the ribs, which had an average mean dose of 19.5 Gy. The skeletal bones had an average mean dose of 21.1 Gy. The brain and liver have average mean doses of 14.8 and 14.1 Gy, respectively. The mean lung dose had an average of 7.6 ± 0.6 Gy for the 20-Gy cohort. Relative to the prescription dose of 20 Gy, the average mean dose for the normal organ volumes ranged from 16.5% to 72.0%, and the average median dose for the normal organs ranged from 16.5% to 71.0%. Dosimetry for patients treated to 12-16 Gy fell within expected ranges based on historical helical tomotherapy plans.

Conclusions

Dosimetric data in the VMAT TMLI plans at our institution are summarized for 20 Gy and 12-16 Gy cohorts. Dose distributions and treatment times are overall similar to plans generated with helical tomotherapy. TMLI may be delivered effectively using a VMAT technique, even at escalated doses.

Genomic and Transcriptomic Predictors of Response from Stereotactic Body Radiation Therapy in Patients with Oligoprogressive Renal Cell Carcinoma

Stereotactic body radiation therapy (SBRT) has been shown to be safe and effective for delaying systemic treatment change among patients with metastatic renal cell carcinoma (mRCC). In this study, we sought to assess the genomic signatures of patients with mRCC who underwent SBRT for oligoprogression. A total of 30 patients with oligoprogressive disease were identified, the majority of whom had clear cell renal cell carcinoma (83.3%) and were receiving first-line treatment (53.3%). Genomic and transcriptomic sequencing were available in 20 and 16 patients, respectively. Duration of systemic treatment (DOT) was categorized as that prior (DOT[P]) and subsequent (DOT[S]) to radiation treatment. The median DOT(P) and DOT(S) were 15.1 and 18.3 mo, respectively, with a median DOT(S)/DOT(P) ratio of 1.4. Patients who had a DOT(S)/DOT(P) ratio of ≥1 had increased expression in pathways related to cell proliferation and development. In contrast, among patients with a ratio of ≤1, the reactive oxygen species pathway was enriched. This study highlights the potential role of genomics and transcriptomics to refine radiation treatment selection in patients with mRCC. PATIENT SUMMARY: In this study, we looked at mutations and genomic expressions among kidney cancer patients who responded better to stereotactic body radiotherapy. We found that enriched expression of certain pathways might play a role in response to radiotherapy.

Long-term follow up of patients with hematological malignancies treated with total body irradiation using intensity modulated radiation therapy

BACKGROUND

With the advent of modern radiation treatment technologies such as intensity modulated radiation therapy (IMRT), there has been increasing interest in its use for total body irradiation (TBI) conditioning regimens for hematopoietic cell transplantation (HCT) to achieve lower doses to critical organs such as the lungs and kidneys. Although this has been reported on in early studies, long-term safety and efficacy data is limited.

METHODS

We performed a single institution matched-pair retrospective analysis of patients treated with IMRT TBI and standard TBI between 2010 and 2020 to provide data on long-term outcomes. Patients with hematologic malignancies, who could not tolerate standing for traditional TBI or who received prior radiation received IMRT TBI. Patients were matched based on age, diagnosis, disease status, and year of transplant, and were matched 2:1 to the standard TBI and IMRT TBI cohorts. Patient and treatment characteristics, toxicity, graft-versus-host disease (GVHD), dosimetry, and outcomes were evaluated for each cohort.

RESULTS

A total of 13 patients met inclusion criteria for the IMRT cohort, leading to 26 patients in the standard TBI cohort. There was no significant difference in relevant clinical factors between the cohorts. Reasons for using IMRT over conventional TBI included being unable to stand (n=5), prior radiation (n=5), and pediatric patient requiring anesthesia (n=3). Among living patients, median follow-up for all patients was 5.1 years in the IMRT TBI cohort and 5.5 years in the standard TBI cohort. The 5-yr estimate of OS was 68% in the IMRT TBI cohort and 60% in the standard TBI cohort (p=0.706). The 5-yr estimate of RFS was 54% in the IMRT TBI cohort and 60% in the standard TBI cohort (p=0.529). There was no clinically significant pneumonitis, nephritis, hypothyroidism, or cataracts reported in the IMRT TBI cohort. 41.7% of patients in the IMRT TBI cohort and 79.2% of patients in the standard TBI cohort experienced Grade II-IV acute GVHD (p=0.023).

CONCLUSIONS

IMRT TBI appears to lead to favorable long-term outcome and dosimetry, and therefore potentially improved long-term toxicity profile compared to conventional TBI. IMRT TBI warrants further investigation as part of larger prospective trials.

Risk of Subsequent Malignant Neoplasms Following Hematopoietic Stem Cell Transplantation with Total Body Irradiation or Total Marrow Irradiation: Insights from Early Follow-Up

Total marrow irradiation (TMI) is an alternative to total body irradiation (TBI) as a component of the conditioning regimen for hematopoietic cell transplantation (HCT), offering the ability to deliver more targeted doses and facilitating organ-sparing. The organ-sparing effect of TMI is theorized to decrease the risk of complications associated with radiation, including subsequent malignant neoplasms (SMNs), while allowing for dosage escalation to improve oncologic outcomes. The purpose of this study was to compare SMNs rates among patients treated with TBI- or TMI-based conditioning regimens. We hypothesized that TMI would yield a rate of SMNs comparable to, if not lower than, TBI. A retrospective matched-pair analysis of patients who underwent allogeneic HCT and received either TBI- or TMI-based conditioning regimens to a total dose of 12 to 20 Gy was performed. A total of 171 patients received TMI-based conditioning and 171 received TBI-based conditioning, matched based on age, sex, diagnosis, and length of follow-up. SMNs were identified from an established long-term follow-up protocol, our institutional cancer registry, and the California Cancer Registry. There were no significant differences in patient and clinical characteristics between the TMI and TBI cohorts except for clinical response status at transplantation and radiation dose. As expected, patients in the TMI received higher radiation doses (median dose, 16.0 Gy for the TMI cohort versus 13.2 Gy for the TBI cohort; P < .001). The median follow-up for both cohorts was 2.0 years (range, .5 to 12.3 years). There was no significant difference in the risk of developing SMNs between the 2 cohorts (P = .81). A total of 9 patients (5.3%) conditioned with TBI and 10 patients (5.8%) conditioned with TMI developed SMNs, at a median of 3.3 years and 1.7 years following HCT, respectively. Excluding nonmelanoma skin cancers and noninvasive neoplasms, 2 patients in the TBI cohort developed SMNs (both melanomas), and 1 patient in the TMI cohort developed an SMN (colon cancer). No patients developed a subsequent hematologic malignancy. TMI-based conditioning is not associated with a significant difference in the risk of developing SMNs compared with TBI-based conditioning during early post-HCT follow-up. Future studies with longer follow-up may be needed to further characterize the risk of SMNs associated with TMI-based conditioning regimens compared with TBI-based regimens.

Pyramidal Decision Support Framework Leverages Subspecialty Expertise across Enterprise to Achieve Superior Cancer Outcomes and Personalized, Precision Care Plans

The complexity of cancer care requires integrated and continuous support to deliver appropriate care. An expert network with complementary expertise and the capability of multidisciplinary care is an integral part of contemporary oncology care. Appropriate infrastructure is necessary to empower this network to deliver personalized precision care to their patients. Providing decision support as cancer care becomes exponentially more complex with new diagnostic and therapeutic choices remains challenging. City of Hope has developed a Pyramidal Decision Support Framework to address these challenges, which were exacerbated by the COVID pandemic, health plan restrictions, and growing geographic site diversity. Optimizing efficient and targeted decision support backed by multidisciplinary cancer expertise can improve individual patient treatment plans to achieve improved care and survival wherever patients are treated.

Current landscape of radiation oncology in esophageal cancer: a narrative review

Background and Objective

Esophageal cancer is an aggressive disease that is the sixth leading cause of cancer-related death worldwide. The overall treatment paradigm for esophageal cancer has changed considerably over the past decade. This narrative review aims to summarize the current landscape of radiation oncology for esophageal cancer.

Methods

A systematic search of the MEDLINE/PubMed database and Clinicaltrials.gov was performed, focusing on studies published within the last 10 years. Our search queried "esophageal cancer [AND] neoadjuvant radiation" as well as "locally advanced esophageal cancer [AND] definitive radiation". Our search resulted in 298 total references. These were manually reviewed, and only 58 references were within our scope of interest ranging from 2012-2022.

Key Content and Findings

For resectable esophageal cancer, neoadjuvant chemoradiation followed by surgery has been defined as the standard of care over the past decade. In patients with incomplete response to neoadjuvant chemoradiation, the benefit of immunotherapy in the adjuvant setting has recently been established. Ongoing studies are examining whether perioperative chemotherapy may be equivalent to neoadjuvant chemoradiation in resectable esophageal adenocarcinoma. For locally advanced esophageal cancer, recent studies have failed to show a benefit with radiation dose escalation in an unselected population, although the use of early positron emission tomography (PET) response to guide dose escalation is currently being studied. Other ongoing studies aiming to improve outcomes in locally advanced esophageal cancer involve using proton beam therapy to reduce toxicity and combining immunotherapy or targeted therapies with chemoradiation to amplify response.

Conclusions

Recent advances in radiation oncology may continue to improve outcomes for patients with esophageal cancer.

Role of radiotherapy in treatment of extramedullary relapse following total marrow and lymphoid irradiation in high-risk and/or relapsed/refractory acute leukemia

BACKGROUND

Total Marrow and Lymphoid Irradiation (TMLI) is a promising component of the preparative regimen for hematopoietic cell transplantation in patients with high-risk acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL). Extramedullary (EM) relapse after TMLI is comparable to TBI and non-TBI conditioning regimens. This study evaluates outcomes of patients treated with radiotherapy (RT) with EM relapse previously treated with TMLI.

METHODS

A retrospective analysis of five prospective TMLI trials was performed. TMLI targeted bones and major lymphoid tissues using image-guided tomotherapy, with total dose ranging from 12 to 20 Gy. EM recurrences were treated at the discretion of the hematologist and radiation oncologist using RT ± chemotherapy. Descriptive statistics and survival analysis were then performed on this cohort.

RESULTS

In total, 254 patients with refractory or relapsed AML or ALL were treated with TMLI at our institution. Twenty-one patients were identified as receiving at least one subsequent course of radiation. A total of 67 relapse sites (median=2 sites/patient, range=1-16) were treated. Eleven relapsed patients were initially treated with curative intent. Following the initial course of subsequent RT, 1-year, 3-year and 5-year estimates of OS were 47.6%, 32.7% and 16.3%, respectively. OS was significantly better in patients treated with curative intent, with median OS of 50.7 months vs 1.6 months (p<0.001). 1-year, 3-year and 5-year estimates of PFS were 23.8%, 14.3% and 14.3%, respectively. PFS was significantly better in patients treated with curative intent, with median PFS of 6.6 months vs 1.3 months (p<0.001). Following RT, 86.6% of the sites had durable local control.

CONCLUSIONS

RT is an effective modality to treat EM relapse in patients with acute leukemia who relapse after HCT achieving high levels of local control. In patients with limited relapse amenable to curative intent, radiation confers favorable long-term survival. Radiation as salvage treatment for EM relapse after HCT warrants further evaluation.

Utilization of model-agnostic explainable artificial intelligence frameworks in oncology: a narrative review

Background and Objective

Machine learning (ML) models are increasingly being utilized in oncology research for use in the clinic. However, while more complicated models may provide improvements in predictive or prognostic power, a hurdle to their adoption are limits of model interpretability, wherein the inner workings can be perceived as a "black box". Explainable artificial intelligence (XAI) frameworks including Local Interpretable Model-agnostic Explanations (LIME) and SHapley Additive exPlanations (SHAP) are novel, model-agnostic approaches that aim to provide insight into the inner workings of the "black box" by producing quantitative visualizations of how model predictions are calculated. In doing so, XAI can transform complicated ML models into easily understandable charts and interpretable sets of rules, which can give providers with an intuitive understanding of the knowledge generated, thus facilitating the deployment of such models in routine clinical workflows.

Methods

We performed a comprehensive, non-systematic review of the latest literature to define use cases of model-agnostic XAI frameworks in oncologic research. The examined database was PubMed/MEDLINE. The last search was run on May 1, 2022.

Key Content and Findings

In this review, we identified several fields in oncology research where ML models and XAI were utilized to improve interpretability, including prognostication, diagnosis, radiomics, pathology, treatment selection, radiation treatment workflows, and epidemiology. Within these fields, XAI facilitates determination of feature importance in the overall model, visualization of relationships and/or interactions, evaluation of how individual predictions are produced, feature selection, identification of prognostic and/or predictive thresholds, and overall confidence in the models, among other benefits. These examples provide a basis for future work to expand on, which can facilitate adoption in the clinic when the complexity of such modeling would otherwise be prohibitive.

Conclusions

Model-agnostic XAI frameworks offer an intuitive and effective means of describing oncology ML models, with applications including prognostication and determination of optimal treatment regimens. Using such frameworks presents an opportunity to improve understanding of ML models, which is a critical step to their adoption in the clinic.

Stereotactic Radiosurgery in a Small Cell Lung Cancer Patient With Numerous Brain Metastases

Small cell lung cancer (SCLC) is an aggressive form of lung cancer characterized by its propensity to metastasize to the brain. When SCLC patients develop brain metastasis, the standard-of-care treatment is whole-brain radiotherapy (WBRT), with the goal of treating both macroscopic and microscopic tumors. However, WBRT is found to be associated with significant morbidity including cognitive impairment. An emerging alternative to WBRT for SCLC is stereotactic radiosurgery (SRS), supported by a recent multi-institutional series and meta-analysis. However, there is limited evidence on the use of SRS when there are greater than 15 lesions from any histology, much less SCLC, where the risk of microscopic disease is felt to be even higher. Here, we present the case of an adult female with extensive-stage SCLC who developed 23 brain metastases. Due to patient preference, these were treated with SRS to a total dose of 20 Gy in one fraction. The patient did not experience any radiation-induced toxicity, including radionecrosis, and had overall favorable intracranial control using SRS alone at the time of her death, which was due to extracranial disease progression. This case adds to the literature suggesting that SRS could be a reasonable option for patients with SCLC. It illustrates that it might be reasonable to seek to expand on who might be considered a candidate for SRS treatment, with a high number of lesions not necessarily representing imminent widespread intracranial disease progression.

The role of concomitant chemoradiotherapy versus radiation alone in T1-3N0 HPV-positive and HPV-negative oropharyngeal squamous cell carcinoma

OBJECTIVE

To evaluate the role of curative intent concurrent chemoradiation (CCRT) vs radiation (RT) alone for T1-T3N0 HPV-positive and HPV-negative oropharyngeal squamous cell cancer (OPSCC).

METHODS

The NCDB was queried for patients diagnosed between 2010 and 2017 with cT1-3N0M0 OPSCC treated with definitive RT or CCRT. Univariable analysis (UVA) and multivariable analysis (MVA) Cox regression analysis was performed with OS as the endpoint. Propensity score matching (PSM) 1:1 was performed. Interaction test to assess heterogeneity of treatment effect.

RESULTS

A total of 2830 patients were queried. On MVA, CCRT was associated with improved OS for T3N0 tumors (HR 0.49; 95% CI 0.39-0.63) but not for T1N0 (HR 1.43; 95% CI 0.99-2.07) and T2N0 (HR 0.92; 95% CI 0.75-1.13). For T3 patients, CCRT improved OS for HPV-negative (HR 0.43; 95% CI 0.31-0.59) and HPV-positive tumors (HR 0.39; 95% CI 0.25-0.61). After PSM, CCRT was not statistically different to RT for patients with T1-2N0 HPV-negative tumors (HR 1.10; 95% CI 0.85-1.43; p = 0.48) and T1-2N0 HPV-positive tumors (HR 1.15; 95% CI 0.79-1.68; p = 0.45). After PSM, CCRT improved OS compared to RT alone for patients with T3N0 HPV-negative (HR 0.43; 95% CI 0.31-0.59; p < 0.01) and HPV-positive tumors (HR 0.39; 95 %CI 0.25-0.61; p < 0.01).

CONCLUSIONS

CCRT is associated with improved OS in HPV-positive and HPV-negative T3N0 OPSCC. RT alone vs. CCRT demonstrated similar OS for T1-T2N0 OPSCC for both HPV negative and HPV positive tumors.

Evaluation of Radiation Oncologist And Trainee Opinions on Residency Expansion, Possible Actions, and Training Program Accreditation Changes in the United States

PURPOSE

To sample U.S. radiation oncologist and trainee opinions regarding residency expansion, what action(s) should be taken to limit residency supply, if any, and the proposed Accreditation Council for Graduate Medical Education (ACGME) changes.

MATERIALS AND METHODS

An online survey was distributed to 1048 attending radiation oncologists by email and ∼800 residents through their program coordinators. The survey asked respondents to rank how strongly they agreed with certain statements regarding residency supply, possible solutions to address any perceived oversupply, and the proposed ACGME changes on a 1-10 disagreement-to-agreement scale. The 16% response rate yielded 294 responses for analysis.

RESULTS

Of the respondents, 90 (30%) were residents, and 204 (70%) were attendings, of whom 117 (57%) were academic, and 87 (43%) were non-academic. 86% agreed that there is a residency oversupply issue, and 91% agreed that actions should be taken to limit residency expansion. On chi-square test, residents and attendings were similarly likely to agree that there is a residency oversupply issue (93% and 89%, p=0.27), although residents were more likely to agree that this oversupply should be acted upon compared to attendings (100% and 88%, p<0.01). Regarding possible solutions, respondents were most likely to agree that further expansion should be limited (90%), program requirements should be made more stringent (76%), and the use of the Supplemental Offer and Acceptance Program should be limited (SOAP) (69%). Proposed ACGME changes that respondents were most likely to agree with included requiring that programs have modern image guidance, stereotactic radiotherapy, and brachytherapy techniques (98%) and have 4+ faculty members and maintain a faculty-to-resident ratio of >1.5:1 (86%). Case log minimums most supported to be increased were 4 uterus (65%) and 11 postmastectomy breast (61%) simulations.

CONCLUSIONS

The majority of respondents agree that there is a residency oversupply issue and that actions should be taken to limit residency expansion and make program requirements more stringent.

Long-Term Follow-Up of Multiple Myeloma Patients Treated with Tandem Autologous Transplantation Following Melphalan and Upon Recovery, Total Marrow Irradiation

BACKGROUND

Total body irradiation in combination with melphalan for multiple myeloma (MM), was shown to be prohibitively toxic. To ameliorate toxicity, total marrow irradiation (TMI), was given as the sole ablative modality during the second cycle of tandem autologous stem cell transplant (TASCT) for MM patients on a phase I-II trial.

STUDY DESIGN

Patients with MM in response or with stable disease and ≤ 18 months from diagnosis received melphalan (MEL) 200 mg/m² and ASCT (Cycle 1), and, after recovery, TMI and ASCT (Cycle 2) followed by maintenance with an IMiD and dexamethasone for up to 12 months. TMI doses were escalated from 1,000 cGy to 1,800 cGy by 200 cGy increments.

RESULTS

Fifty-four patients were to receive TASCT between 2004 and 2011; 8 patients received single ASCT due to patient or physician preference. The median time between melphalan and TMI was 65 days (range 47-125). Thirty patients (55•6%) received TASCT at the maximum tolerated dose of 1600 cGy. The complete and very good partial response rates were 48•1% and 22•2% following ASCT and maintenance. Median follow-up among survivors was 12.3 years (range: 9•2-15•5+). Progression free survival and overall survival at 10 years was 20•4% (95% CI 10•9-31•9) and 38•8% (95% CI: 25•9-51•5). Secondary neoplasms included (1 each) acute myeloid leukemia, papillary thyroid and prostate carcinoma, and melanoma, and we observed 1 case of ductal carcinoma in situ and 4 patients with non-melanoma skin cancers.

CONCLUSION

TMI as part of TASCT was well-tolerated and TASCT lead to a 20.4% PFS plateau. The inclusion of TMI as a conditioning regiment for MM prior to ASCT warrants further study in the context of modern induction and maintenance therapies.

Prognostic Impact of Primary Tumor Extent and Postoperative Radiation Facility Location in Major Salivary Gland Malignancies

Introduction

The treatment of primary salivary malignancies often requires a multimodality approach. The purpose of this analysis was to evaluate the interaction between primary tumor extent and the treatment location of postoperative radiotherapy (PORT) in patients with primary salivary malignancies with respect to survival outcomes.

Methods

Patients with primary salivary malignancies who underwent upfront surgery followed by radiation were queried in the National Cancer Database (NCDB). Patients were stratified by pathologic T stage and whether PORT was performed at the same or different facility as the definitive surgery. Survival outcomes were compared using the Kaplan-Meier method and Cox proportional hazards regression.

Results

A total of 5,553 patients were selected, of which 1,159 had pathologic T4 (pT4) tumors. Patients who received PORT at the same facility compared with a different facility demonstrated superior overall survival (OS) on log-rank analysis (p=0.003). On subgroup analysis, patients with pT4 tumors had superior OS (p=0.015), whereas patients with smaller T1-3 tumors did not. PORT receipt at the same surgical facility was not a significant predictor of OS on multivariable analysis when all patients were included (p=0.057). However, among patients with pT4 tumors, OS was improved in patients who got PORT at the same facility as their surgery (p=0.015), with 10-year survival rates of 38.3 (95% confidence interval (CI): 33%-44%) versus 31% (95%CI: 24%-38%).

Conclusion

OS was improved in patients with primary salivary malignancies who received PORT at the same facility as their surgery, but the difference appears to be primarily driven by patients with pT4 primary tumors.

Adjuvant Scrotal Radiation Therapy As Bridging Therapy to Chimeric Antigen Receptor T-Cell Following Extramedullary Relapse in B-Cell Acute Lymphoblastic Leukemia

Chimeric antigen T-cell (CAR T) therapy is a promising emerging treatment option for patients with relapsed/refractory acute lymphoma. The role of bridging radiotherapy prior to CAR T infusion is an area of increasing interest with a sizable body of literature regarding its use in non-Hodgkin lymphoma, but reports of its use in leukemia are limited. Furthermore, available literature on bridging radiotherapy is limited to the treatment of bulky, often symptomatic disease, as opposed to its role in treating high-risk regions and sanctuary sites. Here, we present an adult male with multiply relapsed B-cell acute lymphoblastic leukemia (B-ALL) who presented with bone marrow relapse and extramedullary relapse in the right testicle. He was successfully treated with right orchiectomy followed by adjuvant bridging radiotherapy to the left testicle and scrotum, followed by CAR T infusion. Under this treatment paradigm, he tolerated the CAR T infusion with minimal toxicity and was without evidence of disease 100 days post-infusion, with normal testosterone levels. This is the first reported case of bridging radiation being used in the adjuvant setting in a patient with hematologic malignancy. This case adds to the growing body of literature that bridging radiation is well-tolerated and can potentially decrease the risk of relapse in high-risk areas following CAR T infusion.

An examination of nationwide trends in accelerated partial breast irradiation - The replacement of breast brachytherapy with intraoperative radiotherapy and external beam radiation

PURPOSE

To examine recent modality utilization trends in accelerated partial breast irradiation (APBI) in the National Cancer Database (NCDB) based on the American Society for Radiation Oncology (ASTRO) guidelines.

MATERIALS AND METHODS

A total of 58,194 patients treated with APBI were identified. Patients were segregated by APBI modality (brachytherapy, external beam radiotherapy [EBRT], and intraoperative radiotherapy ([IORT]). These patients were then further classified by suitability to receive APBI based on ASTRO guidelines. Temporal trends in utilization were evaluated using linear regression. Logistic regression was applied to study factors contributing to APBI modality choice and treatment within the ASTRO suitability groups.

RESULTS

Patients treated with brachytherapy, EBRT, and IORT comprised 70.5%, 17.5%, and 12.0% of patients treated with APBI. From 2008 to 2017, total APBI cases remained relatively stable (-54.1 cases/year, p = 0.161) while brachytherapy cases decreased by 258.7 cases/year (p < 0.001). EBRT and IORT increased by 51.5 cases/year (p = 0.019) and 153.1 cases/year (p < 0.001), respectively. 40.0% of patients treated with APBI were classified as "suitable", which increased from 2010 to 2017 from 35.3% to 45.3% (slope = 1.51%/year, r² = 0.61, p = 0.022). In comparison, 36.0% (36.1% in 2010 to 33.1% in 2017) of patients were classified as "cautionary" (slope = -0.33%/year, r² = 0.63, p = 0.019) and 23.9% (28.6% in 2010 to 21.6% in 2017) of patients were classified as "unsuitable" (slope = -1.18%/year, r² = 0.67, p = 0.012).

CONCLUSIONS

While overall APBI utilization has remained stable since 2008, this has been accompanied by a decline in brachytherapy and a rise in IORT. The causes of these trends should be the topic of future research.

Characterizing impact of positive lymph node number in endometrial cancer using machine-learning: A better prognostic indicator than FIGO staging?

BACKGROUND

Number of involved lymph nodes (LNs) is a crucial stratification factor in staging of numerous disease sites, but has not been incorporated for endometrial cancer. We evaluated whether number of involved LNs provide improved prognostic value.

PATIENTS AND METHODS

Patients diagnosed with node-positive endometrial adenocarcinoma without distant metastasis were identified in the National Cancer Database. We trained a machine-learning based model of overall survival. Shapley additive explanation values (SHAP) based on the model were used to identify cutoffs of number of LNs involved. Results were validated using a Cox proportional hazards regression model.

RESULTS

We identified 11,381 patients with endometrial cancer meeting the inclusion criteria. Using the SHAP values, we selected the following thresholds: 1-3 LNs, 4-5 LNs, and 6+ LNs. The 3-year OS was 82.0% for 1-3 LNs, 74.3% for 4-5 LNs (hazard ratio [HR] 1.38; p < 0.001), and 59.9% for 6+ LNs (HR 2.23; p < 0.001). On univariate Cox regression, PA nodal involvement was a significant predictor of OS (HR 1.20; p < 0.001) but was not significant on multivariate analysis when number of LNs was included (HR 1.05; p = 0.273). Additionally, we identified an interaction between adjuvant therapy and number of involved LNs. Patients with 1-3 involved LNs had 3-year OS of 85.2%, 78.7% and 74.2% with chemoradiation (CRT), chemotherapy, and radiation, respectively. Patients with 6+ involved LNs had 3-yr OS of 67.8%, 49.6%, and 48.9% with CRT, chemotherapy, and radiation, respectively (p < 0.001).

CONCLUSION

Number of involved LNs is a stronger prognostic and predictive factor compared to PA node involvement.

Outcomes between intensity-modulated radiation therapy versus 3D-conformal in early stage glottic cancer

BACKGROUND

The purpose of this study is to evaluate practice patterns and outcomes between intensity-modulated radiation therapy (IMRT) and 3D-conformal radiation (3D-CRT) in early stage glottic cancer.

METHODS

The linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database was used to identify and compare patient and disease profiles, mortality, and toxicity in patients with T1-2 larynx cancer undergoing definitive radiation (RT).

RESULTS

A total of 1520 patients underwent definitive radiation with 3D-CRT (n = 1309) or IMRT (n = 211). Non-white race, those with a Charlson Comorbidity Index ≥2, T2 disease, and those treated at community practices were more likely to undergo IMRT. Rates of IMRT increased from 2006 to 2015, while relative rates of 3D-CRT decreased. Two-year CSS was superior with 3D-CRT (hazard ratio [HR], 0.38; 95% confidence interval [CI], 0.22-0.65; p < 0.001). There was no difference in OS between 3D-CRT and IMRT (p = 0.119).

CONCLUSIONS

Patients receiving 3D-CRT had improved CSS compared to IMRT with no difference in OS.

Age, racial, and ethnic disparities in reported clinical studies involving brachytherapy

PURPOSE

The purpose of this study was to evaluate for age, racial, and ethnic disparities among clinical studies where patients can potentially receive brachytherapy treatment.

METHODS AND MATERIALS

Trials involving brachytherapy for breast, cervical, prostate, and uterine cancers were identified using ClinicalTrials.gov. The age, racial, and ethnic breakdown of the identified trials were compared to US population-estimates derived from the Surveillance, Epidemiology, and End Results (SEER) Program. Primary outcomes were gaps between gaps between mean age and race and ethnic proportions in trials and the US population. Secondary outcomes included proportions of racial and ethnic data reporting. Descriptive statistics, t-tests, χ2 tests, and univariate analysis were used to analyze the data.

RESULTS

A total of 77 trials with reported data were identified, representing 13,580 patients. The overall difference in mean age in the identified trials compared to US population estimates was -2.29 years (p < 0.001), with the largest difference occurring in prostate cancer at -2.72 years (p < 0.001). With the exception of ethnicity in cervical cancer (p = 0.18), all racial and ethnic distributions were statistically significantly different. Overall, the largest disparity was among Asian (-2.65%) and Hispanic patients (-1.05%). Of the 77 trials, 76 (98.7%) reported age, 36 (46.8%) reported race, and 24 (31.2%) reported ethnicity.

CONCLUSIONS

Diversity data is underreported among clinical studies where brachytherapy is a potential treatment component. However, among reported trials, disparities are present albeit relatively small compared to previous studies reporting on disparities in clinical trials. Future efforts should emphasize increased reporting of racial and ethnicity data as well as ensuring inclusion of older patients and minorities.

Combination of yttrium-90 radioembolization with stereotactic body radiation therapy in the treatment of portal vein tumor thrombosis

PURPOSE

Portal vein tumor thrombosis (PVTT) from cancer involving the liver carries a dismal prognosis, with median overall survival (OS) ranging from 2 to 5 months. While treatment with yttrium-90 (90Y) radioembolization alone may improve outcomes, overall prognosis remains poor. We hypothesize that the combination of 90Y radioembolization to the parenchymal component of the tumor and stereotactic body radiation therapy (SBRT) to the vascular component is a safe and effective means of improving outcomes.

MATERIALS AND METHODS

A single center retrospective review identified 12 patients with cancers involving the liver who received both 90Y radioembolization and SBRT to the PVTT between May 2015 to August 2020. Primary endpoint was the 90-day toxicity rate by the Common Terminology Criteria for Adverse Events version 5.0. Secondary endpoints were the best response rate based on the Response Evaluation Criteria in Solid Tumors v1.1, local control rate, portal vein (PV) patency rate, and median OS.

RESULTS

Patients received a median 90Y dose of 104.3 Gy (range, 83.3 to 131.7 Gy) and a median 5-fraction SBRT dose of 32.5 Gy (range, 27.5 to 50 Gy). There were no late toxicities reported, and only 7 acute grade 1 toxicities reported: elevation of liver function tests (17%), nausea (17%), fatigue (17%), and esophagitis (8%). Local control was 83%. 58% of patients had a patent PV after treatment. With a median follow-up time of 28 months, 1-year OS was 55% with a median OS of 14 months.

CONCLUSION

Combination 90Y radioembolization and SBRT appears to be safe and effective in the treatment of PVTT. Larger prospective studies are warranted to better evaluate this combination treatment approach.

Combination radiation and immunotherapy in gynecologic malignancies-a comprehensive review

Definitive and adjuvant radiation and chemoradiation have been mainstays in the management of multiple gynecologic malignancies for decades. However, despite these treatments, the prognosis of patients with locally advanced, recurrent, refractory, and metastatic disease continues to be poor. Over the last decade, immune checkpoint inhibitors have emerged as a promising therapeutic modality, but response rates to monotherapy are low. Mounting basic science and translational research suggests that immunotherapy and radiation may act synergistically with the potential to improve clinical outcomes across multiple disease sites relative to monotherapy with either radiation or immunotherapy alone. Results from early clinical trials in other disease sites, and burgeoning trials within the gynecologic malignancies space hold promise for combined modality treatment. With increasing clinical data supporting combined modality therapy, there is interest in reevaluating treatment paradigms in gynecologic malignancies to improve the current standards of care. In this review, current proposed mechanisms, rationale, and evidence for treatment of gynecologic malignancies with combined radiation and immunotherapy, specifically immune checkpoint inhibitors, will be discussed. Additionally, although currently early and limited, existing clinical data will be summarized as it applies to cervical, endometrial, ovarian, and vulvar cancers. The status of current clinical trials investigating the sequencing, dosing, and fractionation of combined radiation and immunotherapy in these disease sites will also be reviewed.

Improved Survival Outcomes in Medically Fit Patients With Early-Stage Non-Small-Cell Lung Cancer Undergoing Stereotactic Body Radiotherapy

INTRODUCTION

Stereotactic body radiotherapy (SBRT) has been shown to result in excellent disease control rates for early-stage non-small-cell lung cancer (NSCLC). It remains unknown which patients would most benefit from SBRT in treating NSCLC.

PATIENTS AND METHODS

We conducted a retrospective analysis of 346 patients treated with SBRT for early-stage NSCLC at 2 institutions (86 patients from City of Hope National Medical Center and 260 patients from The Newport Beach Radiosurgery Center/Hoag Hospital) from February 2010 to July 2019. The primary endpoint was overall survival (OS). The omnibus test of model coefficients was performed to study the associations between clinical factors and OS. Survival analyses were performed by the log-rank test and Cox proportional hazards regression.

RESULTS

Under the univariate analysis, variables associated with a decreased likelihood of death included age < 65 years (P = .040) and being a surgical candidate (P = .010). Multivariate analysis found that surgical candidates still had a significantly decreased likelihood of death compared to nonsurgical candidates (Hazard ratio 0.360, 95% confidence interval 0.153-0.848, P = .019). Median OS was significantly increased for surgical candidates versus nonsurgical candidates (83 vs 53 months, P = .017). The local failure rate was 9.1%, the locoregional failure rate was 12.7%, and the distant failure rate was 10.7%.

CONCLUSION

Patients who are deemed to be candidates for surgery have improved OS compared to those who are not when treated with SBRT. This raises the question of selection bias in trials comparing surgery with SBRT in NSCLC, as patients who are deemed to be surgical candidates and then go on to undergo surgery may have an inherent OS benefit.

Anal Cancer in the Era of Dose Painted Intensity Modulated Radiation Therapy: Implications for Regional Nodal Therapy

Since the initial development of 5-fluorouracil and mitomycin as a standard of care platform for definitive anal cancer chemoradiotherapy, multiple studies have evaluated the optimal chemotherapy regimen, and radiotherapy technique. Refinements in treatment technique have taken place during an era of improved diagnostic imaging, including incorporation of FDG-PET, with implications for a possible stage migration effect. This has introduced an opportunity to develop stage-specific recommendations for primary tumor, involved nodal, and elective nodal irradiation dose. Elective nodal irradiation remains standard given the low rates of elective nodal failure with current practice, although may be subject to evolving controversy for patients with early stage disease. In this review, development of the current standard of care for anal cancer chemoradiotherapy is reviewed in the context of modern staging and dose-painted radiotherapy treatment techniques.