Quantifying the impact of SpaceOAR hydrogel on inter-fractional rectal and bladder dose during 0.35 T MR-guided prostate adaptive radiotherapy.

PURPOSE: To investigate the impact of rectal spacing on inter-fractional rectal and bladder dose and the need for adaptive planning in prostate cancer patients undergoing SBRT with a 0.35 T MRI-Linac. MATERIALS AND METHODS: We evaluated and compared SBRT plans from prostate cancer patients with and without rectal spacer who underwent treatment on a 0.35 T MRI-Linac. Each group consisted of 10 randomly selected patients that received prostate SBRT to a total dose of 36.25 Gy in five fractions. Dosimetric differences in planned and delivered rectal and bladder dose and the number of fractions violating OAR constraints were quantified. We also assessed whether adaptive planning was needed to meet constraints for each fraction. RESULTS: On average, rectal spacing reduced the maximum dose delivered to the rectum by more than 8 Gy (p < 0.001). We also found that D3cc received by the rectum could be 12 Gy higher in patients who did not have rectal spacer (p < 9E-7). In addition, the results show that a rectal spacer can reduce the maximum dose and D15cc to the bladder wall by more than 1 (p < 0.004) and 8 (p < 0.009) Gy, respectively. Our study also shows that using a rectal spacer could reduce the necessity for adaptive planning. The incidence of dose constraint violation was observed in almost 91% of the fractions in patients without the rectal spacer and 52% in patients with implanted spacer. CONCLUSION: Inter-fractional changes in rectal and bladder dose were quantified in patients who underwent SBRT with/without rectal SpaceOAR hydrogel. Rectal spacer does not eliminate the need for adaptive planning but reduces its necessity.

Prostatic irradiation-induced sexual dysfunction: a review and multidisciplinary guide to management in the radical radiotherapy era (Part I defining the organ at risk for sexual toxicities).

Prostate cancer is the most common malignancy and the second leading cause of cancer-related death in men. Radiotherapy is a curative option that is administered via external beam radiation, brachytherapy, or in combination. Erectile, ejaculatory and orgasm dysfunction(s) is/are known potential and common toxicities associated with prostate radiotherapy. Our multidisciplinary team of physicians and/or scientists have written a three (3) part comprehensive review of the pathogenesis and management radiation-induced sexual dysfunction. Part I reviews pertinent anatomy associated with normal sexual function and then considers the pathogenesis of prostate radiation-induced sexual toxicities. Next, our team considers the associated radiobiological (including the effects of time, dose and fractionation) and physical (treatment planning and defining a novel Organ at Risk (OAR)) components that should be minded in the context of safe radiation treatment planning. The authors identify an OAR (i.e., the prostatic plexus) and provide suggestions on how to minimize injury to said OAR during the radiation treatment planning process.

Prostatic irradiation-induced sexual dysfunction: A review and multidisciplinary guide to management in the radical radiotherapy era (Part II on Urological Management).

Prostate cancer is the most common malignancy in men and the second leading cause of cancer-related death in men. Radiotherapy is a curative option that is administered via external beam radiation, brachytherapy, or in combination. Sexual dysfunction is a common toxicity following radiotherapy, similar to men undergoing radical prostatectomy, but the etiology is different. The pathophysiology of radiation-induced sexual dysfunction is multi-factorial, and the toxicity is a major cause of impaired quality of life among long-term prostate cancer survivors. Management of a patient's sexual function during and after radiotherapy requires multidisciplinary coordination of care between radiation oncology, urology, psychiatry, pharmacy, and dermatology. This review provides a framework for clinicians to better understand prostatic radiotherapy-induced sexual dysfunction diagnosis, evaluation, and a patient-centered approach to toxicity preventive strategies and management.

Elucidating survival and functional outcomes in patients with primary head and neck malignancies treated in academic versus community settings.

BACKGROUND: Differences in treatment outcomes between community or academic centers are incompletely understood. METHODS: Retrospective review of head and neck cancer patients between 2010 and 2020 in a rural health region. Kaplan-Meier curves and log-rank tests were used to evaluate survival outcomes, along with bivariate and multivariable Cox proportional hazards models. Linear regression was used for functional outcomes of tracheotomy and gastrostomy tube dependence. RESULTS: Two hundred and forty-eight patients treated at an academic center were compared with 94 patients treated in community centers. In multivariable analysis, the risk of death (HR = 0.60, p = 0.019), and risk of recurrence were lower (HR = 0.29, p < 0.001) for patients treated in academic centers. Patients treated in community centers had longer gastrostomy tube dependence (p = 0.002). CONCLUSION: Our findings suggest that treatment at an academic center was associated with a lower risk of recurrence and shorter gastrostomy tube dependence compared to treatment in the community.

Estimating the risk of brain metastasis for patients newly diagnosed with cancer.

BACKGROUND: Brain metastases (BM) affect clinical management and prognosis but limited resources exist to estimate BM risk in newly diagnosed cancer patients. Additionally, guidelines for brain MRI screening are limited. We aimed to develop and validate models to predict risk of BM at diagnosis for the most common cancer types that spread to the brain. METHODS: Breast cancer, melanoma, kidney cancer, colorectal cancer (CRC), small cell lung cancer (SCLC), and non-small cell lung cancer (NSCLC) data were extracted from the National Cancer Database to evaluate for the variables associated with the presence of BM at diagnosis. Multivariable logistic regression (LR) models were developed and performance was evaluated with Area Under the Receiver Operating Characteristic Curve (AUC) and random-split training and testing datasets. Nomograms and a Webtool were created for each cancer type. RESULTS: We identify 4,828,305 patients from 2010-2018 (2,095,339 breast cancer, 472,611 melanoma, 407,627 kidney cancer, 627,090 CRC, 164,864 SCLC, and 1,060,774 NSCLC). The proportion of patients with BM at diagnosis is 0.3%, 1.5%, 1.3%, 0.3%, 16.0%, and 10.3% for breast cancer, melanoma, kidney cancer, CRC, SCLC, and NSCLC, respectively. The average AUC over 100 random splitting for the LR models is 0.9534 for breast cancer, 0.9420 for melanoma, 0.8785 for CRC, 0.9054 for kidney cancer, 0.7759 for NSCLC, and 0.6180 for SCLC. CONCLUSIONS: We develop accurate models that predict the BM risk at diagnosis for multiple cancer types. The nomograms and Webtool may aid clinicians in considering brain MRI at the time of initial cancer diagnosis.

When patients are diagnosed with cancer, it is unknown which patients have a significant risk of cancer spread to the brain. Cancer spread to the brain is important to diagnose since it changes how patients are treated and affects their prognosis. This study used a large national database of patients diagnosed with cancer and studied the characteristics that were associated with cancer spread to the brain. The results can be used by doctors to assess the risk of cancer spread to the brain and determine which patients with cancer may benefit most from brain imaging.

Update on adherence to guidelines for time to initiation of postoperative radiation for head and neck squamous cell carcinoma.

BACKGROUND: A prior study reported that over half of patients with HNSCC initiated PORT after 6 weeks from surgery during 2006-2014. In 2022, the CoC released a quality metric for patients to initiate PORT within 6 weeks. This study provides an update on time to PORT in recent years. METHODS: The NCDB and TriNetX Research Network were queried to identify patients with HNSCC who received PORT during 2015-2019 and 2015-2021, respectively. Treatment delay was defined as initiating PORT beyond 6 weeks after surgery. RESULTS: In NCDB, PORT was delayed for 62% of patients. Predictors of delay included age >50, female sex, black race, nonprivate insurance/uninsured status, lower education, oral cavity site, negative surgical margins, increased postoperative length of stay, unplanned hospital readmissions, IMRT radiation modality, treatment at an academic hospital or in the Northeast, and surgery and radiation at different facilities. In TriNetX, 64% experienced treatment delay. Additional associations with prolonged time to treatment included never married/divorced/widowed marital status, major surgery (neck dissection/free flaps/laryngectomy), and gastrostomy/tracheostomy dependence. CONCLUSIONS: There continue to be challenges to timely initiation of PORT.

Concurrent immunotherapy and re-irradiation utilizing stereotactic body radiotherapy for recurrent high-grade gliomas.

BACKGROUND: Clinical trials evaluating immune checkpoint inhibition (ICI) in recurrent high-grade gliomas (rHGG) report 7%-20% 6-month progression-free survival (PFS), while re-irradiation demonstrates 28%-39% 6-month PFS. AIMS: We evaluate outcomes of patients treated with ICI and concurrent re-irradiation utilizing stereotactic body radiotherapy/fractionated stereotactic radiosurgery (SBRT) compared to ICI monotherapy. METHODS AND RESULTS: Patients ≥18-years-old with rHGG (WHO grade III and IV) receiving ICI + SBRT or ICI monotherapy between January 1, 2016 and January 1, 2019 were included. Adverse events, 6-month PFS and overall survival (OS) were assessed. Log-rank tests were used to evaluate PFS and OS. Histogram analyses of apparent diffusion coefficient maps and dynamic contrast-enhanced magnetic resonance perfusion metrics were performed. Twenty-one patients with rHGG (ICI + SBRT: 16; ICI: 5) were included. The ICI + SBRT and ICI groups received a mean 7.25 and 6.2 ICI cycles, respectively. There were five grade 1, one grade 2 and no grade 3-5 AEs in the ICI + SBRT group, and four grade 1 and no grade 2-5 AEs in the ICI group. Median PFS was 2.85 and 1 month for the ICI + SBRT and ICI groups; median OS was 7 and 6 months among ICI + SBRT and ICI groups, respectively. There were significant differences in pre and posttreatment tumor volume in the cohort (12.35 vs. 20.51; p = .03), but not between treatment groups. CONCLUSIONS: In this heavily pretreated cohort, ICI with re-irradiation utilizing SBRT was well tolerated. Prospective studies are warranted to evaluate potential therapeutic benefits to re-irradiation with ICI + SBRT in rHGG.

Primary chondrosarcomas of the larynx treated with proton radiotherapy: A single institutional experience.

BACKGROUND: Primary laryngeal chondrosarcomas are rare entities whose excellent survival rates following resection promote conservative surgical approaches to maintain quality of life without compromising outcomes. There are excellent outcomes in skull base chondrosarcomas treated with maximal safe resection and post-operative proton therapy. Extrapolating from these findings, we report our institutional experience treating symptomatic or growing laryngeal chondrosarcomas using proton beam therapy. CASES: Demographic information, clinical characteristics, treatment details, and follow-up data were collected and summarized. Patients were monitored with serial imaging and examination. Stable disease was defined as no progression of disease on imaging. Two patients underwent subtotal resections followed by post-operative radiotherapy, while two patients received definitive radiotherapy. All patients are currently alive with stable disease at their last follow-up. CONCLUSION: This case series provides initial evidence for excellent outcomes with maximal safe surgical resection followed by proton beam therapy for patients with symptomatic or growing laryngeal chondrosarcomas. Larger studies are warranted to determine the optimal therapeutic approach.

[68Ga]-DOTATATE PET/MRI as an adjunct imaging modality for radiation treatment planning of meningiomas.

BACKGROUND: Meningiomas express high levels of somatostatin receptor 2 (SSTR2). SSTR2-targeted PET imaging with [68Ga]-DOTATATE can aid with distinguishing residual meningioma from reactive changes in the postoperative setting. We present initial dosimetric analyses, acute events, and local control data utilizing [68Ga]-DOTATATE PET/MRI-assisted target delineation for prospectively-treated intermediate-risk meningiomas. METHODS: Twenty-nine patients underwent DOTATATE PET/MRI meningioma evaluation in 2019. Eight patients with 9 postoperative meningiomas met RTOG 0539 intermediate-risk criteria (recurrent WHO grade I, 1/9; WHO grade II, 8/9). Target volumes were created using DOTATATE PET/MRI to determine residual disease and received a nominal dose of 35.0 Gy over 5 fractions. For comparison, cases were recontoured and planned with MRI alone per RTOG 0539 guidelines. Mean and maximum equivalent 2 Gy doses were generated for target volumes and organs at risk (OAR) within 1 cm of the PTV and compared using Wilcoxon matched pairs signed rank test. RESULTS: DOTATATE PET/MRI-guided planning significantly reduced mean PTV (11.12 cm3 compared to 71.39 cm3 based on MRI alone, P < .05) and mean and max dose to the whole brain, optic nerves, and scalp. PET/MRI plans resulted in at least 50% reduction of mean and max doses to the lens, eyes, chiasm, cochlea, brainstem, and hippocampi. One patient experienced focal alopecia. There were no local recurrences at 6 months. CONCLUSION: Incorporating DOTATATE-PET/MRI for postoperative target delineation in patients with intermediate-risk intracranial meningiomas results in PTV reduction and decreased OAR dose. Our findings warrant larger studies evaluating DOTATATE-PET/MRI in the radiotherapeutic planning of postoperative meningiomas.

Time to administration of stereotactic radiosurgery to the cavity after surgery for brain metastases: a real-world analysis.

OBJECTIVE: Publications on adjuvant stereotactic radiosurgery (SRS) are largely limited to patients completing SRS within a specified time frame. The authors assessed real-world local recurrence (LR) for all brain metastasis (BM) patients referred for SRS and identified predictors of SRS timing. METHODS: The authors retrospectively identified BM patients undergoing resection and referred for SRS between 2012 and 2018. Patients were categorized by time to SRS, as follows: 1) ≤ 4 weeks, 2) > 4-8 weeks, 3) > 8 weeks, and 4) never completed. The relationships between timing of SRS and LR, LR-free survival (LRFS), and survival were investigated, as well as predictors of and reasons for specific SRS timing. RESULTS: In a cohort of 159 patients, the median age at resection was 64.0 years, 56.5% of patients were female, and 57.2% were in recursive partitioning analysis (RPA) class II. The median preoperative tumor diameter was 2.9 cm, and gross-total resection was achieved in 83.0% of patients. All patients were referred for SRS, but 20 (12.6%) did not receive it. The LR rate was 22.6%, and the time to SRS was correlated with the LR rate: 2.3% for patients receiving SRS at ≤ 4 weeks postoperatively, 14.5% for SRS at > 4-8 weeks (p = 0.03), and 48.5% for SRS at > 8 weeks (p < 0.001). No LR difference was seen between patients whose SRS was delayed by > 8 weeks and those who never completed SRS (48.5% vs 50.0%; p = 0.91). A similar relationship emerged between time to SRS and LRFS (p < 0.01). Non-small cell lung cancer pathology (p = 0.04), earlier year of treatment (p < 0.01), and interval from brain MRI to SRS (p < 0.01) were associated with longer intervals to SRS. The rates of receipt of systemic therapy also differed significantly between patients by category of time to SRS (p = 0.02). The most common reasons for intervals of > 4-8 weeks were logistic, whereas longer delays or no SRS were caused by management of systemic disease or comorbidities. CONCLUSIONS: Available data on LR rates after adjuvant SRS are often obtained from carefully preselected patients receiving timely treatment, whereas significantly less information is available on the efficacy of adjuvant SRS in patients treated under "real-world" conditions. Management of these patients may merit reconsideration, particularly when SRS is not delivered within ≤ 4 weeks of resection. The results of this study indicate that a substantial number of patients referred for SRS either never receive it or are treated > 8 weeks postoperatively, at which time the SRS-treated patients have an LR risk equivalent to that of patients who never received SRS. Increased attention to the reasons for prolonged intervals from surgery to SRS and strategies for reducing them is needed to optimize treatment. For patients likely to experience delays, other radiotherapy techniques may be considered.

Timing of Adjuvant Fractionated Stereotactic Radiosurgery Affects Local Control of Resected Brain Metastases.

PURPOSE: For resected brain metastases (BMs), stereotactic radiosurgery (SRS) is often offered to minimize local recurrence (LR). Although the aim is to deliver SRS within a few weeks of surgery, a variety of socioeconomic, medical, and procedural issues can cause delays. We evaluated the relationship between timing of postoperative SRS and LR. METHODS AND MATERIALS: We retrospectively identified a consecutive series of patients with BM managed with resection and SRS or fractionated SRS at our institution from 2012 to 2018. We assessed the correlation of time to SRS and other demographic, disease, and treatment variables with LR, local recurrence-free survival, distant recurrence, distant recurrence-free survival, and overall survival. RESULTS: A total of 133 patients met inclusion criteria. The median age was 64.5 years. Approximately half of patients had a single BM, and median BM size was 2.9 cm. Gross total resection was achieved in 111 patients (83.5%), and more than 90% of patients received fractionated SRS. The median time to SRS was 37.0 days, and the LR rate was 16.4%. Time to SRS was predictive of LR. The median time from surgery to SRS was 34.0 days for patients without LR versus 61.0 days for those with LR (P < .01). The LR rate was 2.3% with SRS administered ≤4 weeks postoperatively, compared with 23.6% if SRS was administered >4 weeks postoperatively (P < .01). Local recurrence-free survival was also improved for patients who underwent SRS at ≤4 weeks (P = .02). Delayed SRS was also predictive of distant recurrence (P = .02) but not overall survival. CONCLUSIONS: In this retrospective study, the strongest predictor of LR after postoperative SRS for BM was time to SRS, and a cutoff of 4 weeks was a reliable predictor of recurrence. These findings merit investigation in a prospective, randomized trial.

Trends in the Use of Stereotactic Body Radiotherapy for Treatment of Prostate Cancer in the United States.

Importance: Stereotactic body radiotherapy is a hypofractionated, cost-effective treatment option for localized prostate cancer. Objective: To characterize US national trends and the clinical and socioeconomic factors associated with the use of stereotactic body radiotherapy in prostate cancer. Design, Setting, and Participants: This retrospective cohort study used data collected by the National Cancer Database to assess the clinical and socioeconomic factors among 106 926 men diagnosed as having prostate cancer from 2010 to 2015 who underwent definitive radiotherapy and the trends in the use of this therapy. The initial analysis was performed between January and February 2018, with final updates performed August 2019. Exposure: Stereotactic body radiotherapy, defined as 5 fractions of radiotherapy. Main Outcomes and Measures: Temporal trends and clinical and sociodemographic factors associated with stereotactic body radiotherapy use. Results: In total, 106 926 patients diagnosed as having localized prostate cancer between 2010 and 2015 and receiving definitive radiotherapy were identified. White patients composed 77.3% of this cohort, whereas black patients composed 18.7%. Government-issued insurance was used by 61.2% of patients. More than 80% of patients had a Charlson-Deyo Comorbidity Index score of 0 (range, 0 to ≥3, with lower numbers indicating fewer comorbidities). In the study population, 25.7% had low-risk disease; 26.3%, favorable intermediate-risk disease; 23.3%, unfavorable intermediate-risk disease; and 24.7%, high-risk disease. The proportion of patients who underwent radiotherapy and received stereotactic body radiotherapy (a total of 5395 patients) increased from 3.1% in 2010 to 7.2% in 2015 (odds ratio, 0.36; 95% CI, 0.33-0.40; P < .001). Among the entire cohort, patients received a median dose of 36.25 Gy (range, 30.00-50.00 Gy). Androgen deprivation therapy use increased significantly as disease risk level increased among all patients receiving radiotherapy (9.5% with low risk to 76.6% with high risk; P = .02) and among those receiving stereotactic body radiotherapy (4.1% with low risk to 33.2% with high risk; P = .04) or not receiving stereotactic body radiotherapy (9.9% with low risk to 77.6% with high risk; P = .04). Patients treated at an academic center, living in an urban area, or possessing higher incomes and those who were healthier, white individuals, or were diagnosed as having lower-risk prostate cancer had higher odds of receiving stereotactic body radiotherapy. Conclusions and Relevance: This study found that stereotactic body radiotherapy use in prostate cancer more than doubled from 2010 to 2015 but accounted for less than 10% of all patients undergoing radiotherapy. Androgen deprivation therapy use increased with disease risk among patients overall, regardless of receiving stereotactic body radiotherapy. Socioeconomic and clinical determinants of stereotactic body radiotherapy included risk category, Charlson-Deyo Comorbidity Index score, facility type and location, income, race/ethnicity, and year of diagnosis. These results are hypothesis generating; further studies evaluating potential disparities in stereotactic body radiotherapy use in localized prostate cancer are warranted.

Intraoperative brachytherapy for resected brain metastases.

Brain metastases are the most common intracranial malignancies in adults. Surgical resection is the preferred treatment approach when a pathological diagnosis is required, for symptomatic patients who are refractory to steroids, and to decompress lesions causing mass effect. Radiotherapy is administered to improve local control rates after surgical resection. After a brief review of the literature describing the treatment of brain metastases using whole-brain radiotherapy, postoperative stereotactic radiosurgery, preoperative radiosurgery, and brachytherapy, we compare patient-related, technical, practical, and radiobiological considerations of each technique. Finally, we focus our discussion on intraoperative brachytherapy, with an emphasis on the technical aspects, benefits, efficacy, and outcomes of studies utilizing permanent Cs-131 implants.

Elective Neck Dissection, but Not Adjuvant Radiation Therapy, Improves Survival in Stage I and II Oral Tongue Cancer with Depth of Invasion >4 mm.

Purpose/objective(s) In early-stage, node negative oral tongue cancer, there is limited data supporting tumor depth of invasion (DOI) as an indication for post-operative radiotherapy (PORT) to the primary site. The primary aim of this study is to examine the effect of tumor DOI and PORT on overall survival (OS). Materials and methods The National Cancer Database (NCDB) was used to query patients with AJCC stage I and II oral tongue cancer (2006-2013). Patients were stratified by receipt of PORT, elective neck dissection (ND), and DOI (≤4 mm or >4 mm). Kaplan-Meier analysis was performed to compare OS (using the log-rank test) between PORT versus no-PORT. Multivariable Cox proportional hazards regression model performed to evaluate the independent effect of PORT and neck dissection on OS. Results Among 939 patients, 69.3% were clinical stage I, 67.4% received ND, 23.4% had DOI >4 mm, and 10.4% received PORT. The addition of PORT did not improve OS with tumor DOI ≤4 mm (p = 0.634) or >4 mm (p = 0.816). The addition of elective neck dissection improved OS for DOI >4 mm (p = 0.010), but not for ≤4 mm (p = 0.128). On multivariable analysis, ND improved OS if DOI >4 mm (HR, 0.37; 95% CI, 0.17-0.81 [p = .012]), when also controlling for age, sex, PORT status, clinical stage, and pathological stage. Conclusion Tumor DOI should not be used as a sole indication for PORT in early stage oral tongue cancers. Elective neck dissection at the time of excision of the primary tumor results in higher OS for tumors with DOI >4 mm.

Excellent Outcomes in a Geriatric Patient with Multiple Brain Metastases Undergoing Surgical Resection with Cesium-131 Implantation and Stereotactic Radiosurgery.

Stereotactic radiosurgery (SRS) is a minimally invasive, focal treatment option for brain metastases. Multiple studies support its use in various settings as an effective, comparable alternative to surgery and whole-brain radiation therapy (WBRT). Here, we present excellent outcomes in a 90-year-old patient who underwent SRS after initially presenting at age 84 with multiple brain metastases of an unknown primary, as well as undergoing SRS to a site of tumor recurrence that was initially treated with surgical resection and intraoperative cesium-131 (Cs-131) brachytherapy. To our knowledge, this is one of the first reports describing the effective use of both intraoperative brachytherapy and SRS in the management of multiple brain metastases.

Current and emerging roles of functional imaging in radiation therapy.

The advent of functional imaging facilitates the acquisition of patient-specific tumor characteristics, including its metabolic state and regional oxygen tension. Recent advances promote incorporating this information with data obtained from current imaging techniques, such as MRI and CT, to manage various malignancies. Functional imaging's vital roles progressively evolved to include: aiding in diagnosis, improving radiation treatment planning, differentiating tumor volume from surrounding normal tissues which enables dose escalation to the former while improving sparing of the latter, adapting radiation therapy regimens according to a tumor's response to initial treatment, and assessing radiation therapy response and toxicity. This review explores functional imaging in radiation oncology in the context of these five applications, as well as its comparison to, and integration with, existing imaging modalities. In parallel with advances in functional imaging and understanding of tumor microbiology, the emergence of diverse tracers provides a plethora of options to distinguish and manage malignancies on the basis of specific metabolic processes and changing microenvironmental cues. Current limitations, potential concerns, and future innovations of functional imaging are also discussed.