Characterization of Photon Intensity Modulated Radiation Therapy Robustness in Patients With Prostate Cancer as a Proposed Benchmark for Proton Therapy Robustness Evaluation.

PURPOSE: Robustness evaluation is increasingly used in particle therapy planning to assess clinical target volume (CTV) coverage in the setting of setup and range uncertainty. However, no clear standard exists as to an acceptable degree of plan robustness. The aim of this study is to quantify x-ray robustness parameters, as this could inform proton planning when held to a similar standard. METHODS AND MATERIALS: Consecutive patients with prostate adenocarcinoma treated with definitive x-irradiation to the prostate alone at a single institution in 2019 were retrospectively reviewed. CTV to planned target volume (PTV) margins of 7 mm in all directions, except 4 mm posteriorly, were used in the main cohort. Plans were normalized to PTV V100% ≥ 95%. Patient setup errors were simulated by shifting the isocenter relative to the patient in each of the cardinal directions. The magnitude of each shift equaled the magnitude of the CTV to PTV expansion in that direction. Range uncertainty was set to 0%. RESULTS: A total of 27 patients were evaluated. The mean (SD) nominal plan CTV V100% was 99.6% (1.1%). The mean (SD) worst-case shift CTV V100% was 97.2% (2.8%). The mean (SD) nominal and worst-case CTV V95% were 100% (0%) and 99.7% (0.5%), respectively. A worst-case CTV V100% > 90% and a worst-case CTV V95% > 99% were achieved in over 95% of plans. The mean (SD) nominal and worst-case rectal V70 Gy were 2.37 cc (1.00 cc) and 11.60 cc (3.16 cc), respectively. The mean (SD) nominal and worst-case bladder V60 Gy were 7.8% (4.8%) and 14.5% (9.3%), respectively. Paired 2-tailed t tests comparing the nominal to worst-case dose-volume histograms were significant for each dosimetric parameter (P < .01). CONCLUSIONS: X-ray planning uses PTV margins to inherently provide robustness to patient setup errors. Although the prostate remains well covered in various setup uncertainty scenarios, organs at risk routinely exceeded nominal treatment plan institutional constraints in the worst-case scenarios. Robustness metrics obtained from x-ray plans could serve as a benchmark for proton therapy robust optimization and evaluation.

Prostate Stereotactic Body Radiation Therapy With a Focal Simultaneous Integrated Boost: 5-Year Toxicity and Biochemical Recurrence Results From a Prospective Trial.

PURPOSE: Stereotactic body radiation therapy (SBRT) is increasingly used as a definitive treatment option for patients with prostate adenocarcinoma. The aim of this study was to assess the late toxicity, patient-reported quality of life outcomes, and biochemical recurrence rates after prostate SBRT with simultaneous integrated boost (SIB) targeting lesions defined by magnetic resonance imaging (MRI). METHODS AND MATERIALS: Patients were eligible if they had biopsy-proven low- or intermediate-risk prostate adenocarcinoma, one or more focal lesions on MRI, and an MRI-defined total prostate volume of <120 mL. All patients received SBRT delivered to the entire prostate to a dose of 36.25 Gy in 5 fractions with an SIB to the lesions seen on MRI to 40 Gy in 5 fractions. Late toxicity was defined as any possible treatment-related adverse event occurring after 3 months from the completion of SBRT. Patient-reported quality of life was ascertained using standardized patient surveys. RESULTS: A total of 26 patients were enrolled. Six patients (23.1%) had low-risk disease and 20 patients had intermediate-risk disease (76.9%). Seven patients (26.9%) received androgen deprivation therapy. Median follow-up was 59.5 months. No biochemical failures were observed. Three patients (11.5%) experienced late grade 2 genitourinary (GU) toxicity requiring cystoscopy, and 7 patients (26.9%) had late grade 2 GU toxicity requiring oral medications. Three patients (11.5%) had late grade 2 gastrointestinal toxicity characterized by hematochezia requiring colonoscopy and steroids per rectum. There were no grade 3 or higher toxicity events observed. The patient-reported quality-of-life metrics at the time of last follow-up were not significantly different than the pre-treatment baseline. CONCLUSIONS: The results of this study support that SBRT to the entire prostate to a dose of 36.25 Gy in 5 fractions with focal SIB to 40 Gy in 5 fractions has excellent biochemical control and is not associated with undue late gastrointestinal or GU toxicity or long-term quality of life decrement. Focal dose escalation with an SIB planning approach may be an opportunity to improve biochemical control while limiting dose to nearby organs at risk.

Carotid body paraganglioma metastatic to spine causing cord compression: a case report.

BACKGROUND: Carotid body tumors (CBTs) are rare neuroendocrine neoplasms arising near the carotid bifurcation with a reported incidence of 1 to 2 cases in 100,000 patients. Most CBTs are sporadic, benign, slow-growing, and non-secreting, but untreated CBTs can grow locally to compress the nearby blood vessels, esophagus, and airway. Regional metastases can occur in 5% to 10% of cases, but distant metastases are exceedingly rare, occurring in roughly 1-2% of cases. As such, the optimal treatment for metastatic CBTs is not well-defined. We report a rare case of a patient with CBT distant metastases causing spinal cord compression. CASE PRESENTATION: A 40-year-old African American female presented with a right neck mass, headaches, vertigo, tinnitus, hoarseness, and dysphagia. Imaging demonstrated a Shamblin II right neck mass; subsequent transcervical resection and pathology showed a carotid body paraganglioma. The patient recurred locally near the carotid bifurcation, so she underwent Stereotactic Body Radiation Therapy to the recurrent right neck disease. She later re-presented with new onset bilateral lower extremity weakness, dysmetria, and numbness. She was found to have metastatic disease to the thoracic spine causing spinal cord compression. She underwent laminectomy, tumor resection, and posterior fixation followed by adjuvant radiation therapy. She was started on systemic therapy with sunitinib. She eventually progressed with metastatic disease to the right iliac bone, which was treated with palliative radiotherapy. Second line systemic therapy with capecitabine and temozolomide was started. At last follow up, the patient was asymptomatic with stable persistent disease. CONCLUSIONS: Paragangliomas often exhibit a prolonged interval to the development of progression; locoregional recurrences or rare distant metastases have been reported to occur as many as 20 years from diagnosis. The natural course of CBTs in other cases as well as the present case call into question the idea that CBTs are truly benign; instead CBTs may be indolent tumors with metastatic potential. Treatment choices for CBTs include surgical resection, radiation therapy, and systemic therapy, though the optimal treatment regimen for metastatic CBTs is not well-defined. A more advanced understanding of CBT pathophysiology, disease classification, risk stratification, and treatment options is needed to improve outcomes for patients.

Cardiac Myxoma with Cerebral Metastases and Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma: A Case Report and Review.

Background Cardiac myxomas, the most common primary cardiac tumors, are generally benign neoplasms. Primary cardiac lymphoma is a rare cardiac malignancy with a very poor prognosis. Here we present a case of a cardiac myxoma with cerebral metastases and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) arising within the cerebral metastases. Case description A 62-year-old man, who presented with symptoms of multiple transient ischemic attacks, was found to have a left atrial myxoma. Twelve months after excision of the myxoma, the patient experienced a recurrence of neurologic symptoms. Brain magnetic resonance imaging revealed multiple hemorrhagic masses. Craniotomy was performed to resect the lesions. Histopathologic examination confirmed cardiac myxoma metastases and a small lymphocytic infiltrate within the tumor consistent with CLL/SLL. Conclusion Including the present case, there are 27 cases of cardiac myxoma cerebral metastases and 22 cases of lymphomas arising within myxomas. The present case is the first known instance of both entities in the same patient. There is no standard management for either cardiac myxoma metastases or lymphoma within a myxoma. For both diseases, surgical excision is the primary treatment modality, but postoperative chemotherapy and/or radiation have been attempted. Myxomas may create a chronic inflammatory state that could lead to the development of CLL/SLL.

Controlling heterogeneity within the lymphatic target volume for dose painted treatment of prostate cancer.

INTRODUCTION: For patients with high risk prostate cancer, conventionally fractionated treatment of the pelvic lymphatics and hypofractionated treatment to the prostate can be delivered simultaneously with dose painting. The purpose of this technical note is to highlight unexpected hot spots within the low dose lymphatic target volume as a clinical problem that we have observed with dose painting, and to describe a simple approach to account for this during treatment planning. SUMMARY: We describe the creation of a control structure that can be incorporated into the optimization objective function. An upper constraint objective can be placed on the control structure such that heterogeneity within the plan is limited to the area near the high dose target volume and better emulates the dosimetry of a conventionally fractionated sequential boost plan.