Faculty Bibliography

PURPOSE/OBJECTIVE:To compare the use of cone-beam computed tomography versus contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) in the calculation of liver volume and planned dose for yttrium-90 radioembolization. MATERIALS AND METHODS/METHODS:The study retrospectively assessed 47 consecutive patients who underwent resin Y-90 radioembolization consecutively over a 2-year period at a single center. Volume calculation software was used to determine perfused lobar liver volumes from cone-beam CT (CBCT) images obtained during mapping angiography. CBCT-derived volumes were compared with perfused lobar volume derived from contrast-enhanced CT and MRI. Nominal activities as determined by the SIR-Spheres Microspheres Activity Calculator were similarly calculated and compared using both CBCT and conventionally acquired volumes. RESULTS:A total of 82 hepatic lobes were assessed in 47 patients. The mean percentage difference between combined CT-MRI- and CBCT-derived calculated lobar volumes was 25.3% (p = 0.994). The mean percentage difference in calculated dose between the two methods was 21.8 ± 24.6% (p = 0.42). Combined left and right lobar CT-derived dose difference was less than 10% in 22 lobes, between 10 and 25% in 20 lobes, between 25 and 50% in 13 lobes and greater than 50% in 5 lobes. Combined left and right lobar MRI-derived dose difference was less than 10% in 11 lobes, between 10 and 25% in 7 lobes, between 25 and 50% in 2 lobes and greater than 50% in 1 lobe. CONCLUSIONS:Although volume measurements derived from CT/MRI did not differ significantly from those derived from CBCT, variability between the two methods led to large and unexpected differences in calculated dose.

Background/UNASSIGNED:Prostate cancer survivors commonly experience late-onset lower urinary tract symptoms following radiotherapy. We aimed to compare lower urinary tract symptoms in patients treated with stereotactic body radiotherapy (SBRT) to those treated with a combination of lower dose SBRT and supplemental intensity-modulated radiotherapy (SBRT + IMRT). Methods/UNASSIGNED:Subjects with localized prostate carcinoma scheduled to receive SBRT or a combination of SBRT and IMRT were enrolled and followed for up to 2 years after treatment completion. Participants treated with SBRT received 35-36.25 Gy in 5 fractions, while those treated with SBRT + IMRT received 19.5 Gy of SBRT in 3 fractions followed by 45-50.4 Gy of IMRT in 25-28 fractions. Urinary symptoms were measured using the American Urological Association (AUA) Symptom Score. Results/UNASSIGNED:Two hundred patients received SBRT (52% intermediate risk, 37.5% low risk according to D'Amico classification) and 145 patients received SBRT + IMRT (61.4% high risk, 35.2% intermediate risk). Both groups experienced a transient spike in urinary symptoms 1 month after treatment. More severe late urinary flare (increase in AUA scores ≥ 5 points from baseline to 1 year after treatment completion and an AUA score ≥ 15 at 1 year after treatment) was experienced by patients who received SBRT compared to those treated with SBRT + IMRT. Conclusion/UNASSIGNED:Participants who received SBRT and supplemental IMRT experienced less severe late urinary flare 1 year after treatment compared to those who received higher dose SBRT alone. This information can be used by clinicians to provide patients with anticipatory counseling to mitigate any psychological burden that comes with unanticipated late urinary toxicities.

BACKGROUND:The majority of patients with pancreatic cancer are diagnosed with metastatic disease at presentation. Nevertheless, local progression is responsible for up to 30% of deaths and can lead to significant morbidity. As a consequence, further exploration of effective methods of local control and palliation is essential. Stereotactic body radiation therapy (SBRT) is a widely utilized technique for the treatment of localized pancreatic cancer. Here, we report our experience with SBRT and chemotherapy for the local treatment of the metastatic patient population. METHODS:This single institution retrospective review analyzed 20 patients with pathologically diagnosed metastatic adenocarcinoma of the pancreas. All patients underwent fiducial placement under endoscopic ultrasound (EUS) guidance. SBRT was delivered in five fractions to a total dose of 25 to 30 Gy. Patients received concurrent (given within 1 week of the start of SBRT) or sequential chemotherapy. Local tumor control was evaluated using Response Evaluation Criteria in Solid Tumors. Toxicity was graded using Common Terminology Criteria for Adverse Events version 4.03. Local control and overall survival were reported using the Kaplan-Meier method. RESULTS:Patient median age was 64 years, and the median pre-treatment Eastern Cooperative Oncology Group performance status was 1. All patients received chemotherapy and half of the patients (10 of 20) received concurrent chemotherapy with folinic acid, fluorouracil, and oxaliplatin or fluorouracil, leucovorin, irinotecan, and oxaliplatin. Nearly all patients (19 of 20) received post-SBRT chemotherapy. Median time from pathological diagnosis to SBRT was 3.9 months. The twelve-month local control and overall survival were 43 and 53%, respectively. However, in patients with planning target volume (PTV) targets smaller than the population median, the 12-month local control was 78%. Median time to local progression (17.8 vs. 3.0 months, p = 0.02) and overall survival (24.9 vs. 8.8, p = 0.001) were also significantly improved in this smaller PTV cohort. Though not statistically significant, there was a trend towards improvement in local control (17.8 vs. 4.3 months, p = 0.17) and overall survival (16.7 vs. 9.7 months, p = 0.087) for those who received concurrent versus sequential chemotherapy, respectively. Lastly, there were no reported grade 3-5 late toxicities. CONCLUSIONS:As systemic therapies improve, the local management of pancreatic cancer will become increasingly important. Here, we report significantly improved local control with SBRT of smaller PTV tumors with concurrent chemotherapy. Five-fraction SBRT offers a quick and effective modality of local tumor control with minimal toxicity in the metastatic pancreatic cancer population.

Purpose/Objective: High-grade glioma is the most common primary malignant tumor of the CNS, with death often resulting from uncontrollable intracranial disease. Radiation dose may be limited by the tolerance of critical structures, such as the brainstem and optic apparatus. In this report, long-term outcomes in patients treated with conventionally fractionated stereotactic boost for tumors in close proximity to critical structures are presented. Materials/Methods: Patients eligible for inclusion in this single institution retrospective review had a pathologically confirmed high-grade glioma status post-surgical resection. Inclusion criteria required tumor location within one centimeter of a critical structure, including the optic chiasm, optic nerve, and brainstem. Radiation therapy consisted of external beam radiation followed by a conventionally fractionated stereotactic boost. Oncologic outcomes and toxicity were assessed. Results: Thirty patients eligible for study inclusion underwent resection of a high-grade glioma. The median initial adjuvant EBRT dose was 50 Gy with a median conventionally fractionated stereotactic boost of 10 Gy. All stereotactic treatments were given in 2 Gy daily fractions. Median follow-up time for the entire cohort was 38 months with a median overall survival of 45 months and 5-year overall survival of 32.5%. The median freedom from local progression was 45 months, and the 5-year freedom from local progression was 29.7%. Two cases of radiation retinopathy were identified following treatment. No patient experienced toxicity attributable to the optic chiasm, optic nerve, or brainstem and no grade 3+ radionecrosis was observed. Conclusions: Oncologic and toxicity outcomes in high-grade glioma patients with tumors in unfavorable locations treated with conventionally fractionated stereotactic boost are comparable to those reported in the literature. This treatment strategy is appropriate for those patients with resected high-grade glioma in close proximity to critical structures.