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Whole-brain radiation treatment is often considered for patients with leptomeningeal disease. There are limited reports of the development of radiation necrosis after whole-brain radiation treatment and fewer associating the presence of germline mutations with risk. We present a case report to highlight the need for consideration of radiosensitizing mutations when recommending radiation therapy. [ABSTRACT FROM AUTHOR]

• Nearly 7 % of youth and young adults report concurrent cannabis and e-cigarette use. • Older age, male gender, and bisexual identity are risk factors for concurrent cannabis and e-cigarette use. • Household smoking, higher sensation seeking, and lower parental education are also risk factors for concurrent cannabis and e-cigarette use. • Demographic variables can help to guide efforts to prevent and reduce concurrent cannabis and e-cigarette use. Given that cannabis and e-cigarettes are among the most commonly used substances among young people, there is a need to identify risk factors for concurrent cannabis consumption and nicotine vaping among youth and young adults. Data were obtained from the Truth Longitudinal Cohort, collected from September 2020 to March 2021, among a cohort aged 15–24 years (N = 6379). Chi-square tests were conducted to detect differences in sample characteristics by dual use status (never e-cigarette and never cannabis users, never cannabis and former/noncurrent e-cigarette users, never e-cigarette and former/noncurrent cannabis users, former/noncurrent e-cigarette and cannabis users, current e-cigarette only users, current cannabis only users, and concurrent cannabis and e-cigarette dual users). Multinomial logistic regression was used to determine key demographic variables predicting dual use status. Household tobacco use (Relative Risk Ratio, RRR = 4.93), higher sensation seeking (RRR = 3.98), and mental health score (RRR = 2.58) were associated with higher risk of dual use. Being 15–17 years (RRR = 0.22), being female (RRR = 0.59) and having parents with an education level of some college or more (RRR = 0.64) were associated with lower risk of dual use. Findings suggest the need to carefully monitor cannabis and vaping nicotine among young people. The identification of risk factors provides additional guidance for prevention and treatment efforts, suggesting the need to address use of both substances and target those most at risk. [ABSTRACT FROM AUTHOR]

• Stabilizing organ-at-risk anatomy (OAR) is essential. • Interfraction prostate bed volume is stable despite deformable surrounding organs. • Target underdosing and OAR overdosing is avoided in post-prostatectomy radiotherapy. • Volumetric and dosimetric changes from rotation and intrafraction motion are minor. • Shape of prostate bed may also influence target coverage. Stereotactic body radiotherapy (SBRT) in the post-prostatectomy setting is investigational. A major concern is the deformable prostate bed clinical target volume (CTV) and the closely juxtaposed organs-at-risk (OARs). We report a volumetric and dosimetric analysis of kilovoltage cone-beam CT (CBCT) data from the first 18 patients enrolled on a phase II trial of post-prostatectomy SBRT. With instructions on bladder filling and rectal preparation, we hypothesized acceptable CTV coverage while minimal overdosing to OARs could be achieved. All patients received 5 fractions of 6–6.8 Gy to the prostate bed. CBCT were taken prior to and halfway through each fraction. CTV and OARs were contoured for each CBCT. Changes in inter- and intra-fraction volume and dose were calculated. Relative changes in CTV V95%, bladder V32.5 Gy, and rectal V32.5 Gy and V27.5 Gy were evaluated. Interfraction CTV volume remained stable, with median change +5.69% (IQR −1.73% to +9.84%). CTV V95% exhibited median change −0.74% (IQR −9.15% to −0.07%). Volumetric and dosimetric changes were minor from interfraction rotation and intrafraction motion. CTV V95% was ≥93% in 13 of 18 (72%) patients; in the remaining five, median change was −14.09% (IQR −16.64% to −13.56%). Interfraction CTV volume change was significantly larger among patients with CTV V95% <93% (+25.04% vs. +2.85%, p = 0.002). With specific bladder and rectum filling protocols, CTV underdosing and overdosing to bladder and rectum are avoided in majority of patients. Changes in CTV shape may account for the underdosing that may be observed. [ABSTRACT FROM AUTHOR]

Postoperative radiation therapy (RT) is an underused standard-of-care intervention for patients with prostate cancer and recurrence/adverse pathologic features after radical prostatectomy. Although stereotactic body RT (SBRT) is a well-studied and convenient option for definitive treatment, data on the postprostatectomy setting are extremely limited. The purpose of this study was to evaluate short-term physician-scored genitourinary (GU) and gastrointestinal (GI) toxicities and patient-reported outcomes after postprostatectomy SBRT. The SCIMITAR trial was a phase 2, dual-center, open-label, single-arm trial that enrolled patients with postoperative prostate-specific antigen >0.03 ng/mL or adverse pathologic features. Coprimary endpoints were 4-year biochemical recurrence–free survival, physician-scored acute and late GU and GI toxicities by the Common Terminology Criteria for Adverse Events (version 4.03) scale, and patient-reported quality-of-life (QOL) outcomes, as represented by the Expanded Prostate Cancer Index-26 and the International Prostate Symptom Score. Patients received SBRT 30 to 34 Gy/5 fractions to the prostate bed ± bed boost ± pelvic nodes with computed tomography (CTgRT) or magnetic resonance imaging guidance (MRgRT) in a nonrandomized fashion. Physician-scored toxicities and patient-reported QOL outcomes were collected at baseline and at 1, 3, and 6 months of follow-up. Univariable and multivariable analyses were performed to evaluate predictors of toxicities and QOL outcomes. One hundred participants were enrolled (CTgRT, n = 69; MRgRT, n = 31). The median follow-up was 29.5 months (CTgRT: 33.3 months, MRgRT: 22.6 months). The median (range) prostate bed dose was 32 (30-34) Gy. Acute and late grade 2 GU toxicities were both 9% while acute and late grade 2 GI toxicities were 5% and 0%, respectively. Three patients had grade 3 toxicity (n = 1 GU, n = 2 GI). No patient receiving MRgRT had grade 3 GU or grade ≥2 GI toxicity. Compared with CTgRT, MRgRT was associated with a 30.5% (95% confidence interval, 11.6%-49.5%) reduction in any-grade acute GI toxicity (P =.006). MRgRT was independently associated with improved any-grade GI toxicity and improved bowel QOL. Postprostatectomy SBRT was well tolerated at short-term follow-up. MRgRT may decrease GI toxicity. Longer toxicity and/or efficacy follow-up and randomized studies are needed. [ABSTRACT FROM AUTHOR]