Malignant mixed mullerian tumors: a SEER database review of rurality and treatment modalities on disease outcome

Introduction

Malignant Mixed Mullerian Tumors (MMMT) are rare and poorly understood sarcomas with limited research on risk factors, pathogenesis, and optimal treatments. This study aimed to address this knowledge gap and explore the impact of community size, patient characteristics, disease characteristics, and treatment modalities on MMMT outcomes.

Methods

Using the Surveillance, Epidemiology, and End Results database (SEER), the largest SEER cohort to date of 3,352 MMMT patients was analyzed for demographic factors, treatment modalities, and histologic characteristics. Data was processed, including the removal of incomplete entries, and analyzed in Python 3.1 using packages scikit-learn, lifelines, and torch; log-rank analysis and Cox proportional hazards models were used to evaluate a number of demographic characteristics and disease characteristics for significance in regard to survival.

Results

Our study found adjuvant radiotherapy and chemotherapy significantly improved survival, with modest benefits from neoadjuvant chemotherapy. Our findings also suggest age at diagnosis, disease grade, and suburban versus rural geographic locations may play key roles in patient prognosis. On multivariable analysis both disease Grade and surgical treatment were significant factors.

Discussion

MMMTs remain challenging, but appropriate treatment appears to enhance survival. The present findings suggest opportunities for improved outcomes and treatment strategies for patients with MMMTs.

Novel combination of GammaTile cesium-131 brachytherapy with 5-aminolevulinic acid fluorescence-guided resection in the re-irradiation of pediatric recurrent high-grade glioma: illustrative case

BACKGROUND

Herein, the authors describe the successful utilization of 5-aminolevulinic acid (5-ALA) and the first case of GammaTile cesium-131 therapy in a pediatric patient with recurrent high-grade glioma. 5-ALA was utilized to optimize gross-total resection prior to GammaTile implantation. After conversion to an equivalent dose in 2-Gy fractions (EQD2), a composite was made of the GammaTile dose with the initial external beam radiotherapy. Two hypothetical plans consisting of a standard hypofractionated strategy for glioma reirradiation and a CyberKnife plan using GammaTile's planning target volume were developed and likewise underwent EQD2 conversion and composite plan generation with the initial radiotherapy.

OBSERVATIONS

5-ALA was useful in achieving gross-total resection with no acute toxicity from the surgery or GammaTile irradiation. When compared with the hypothetical composite doses, GammaTile's composite, axium point dose (D0.03cc) to the brainstem was 32.9 Gy less than the hypofractionated and the CyberKnife composite plans at 38.7 Gy and 40.2 Gy, respectively. The right hippocampus demonstrated a substantially reduced composite plan dose with GammaTile with a D0.03cc of 62.4 Gy versus 71.7 and 80.7 Gy for the hypofractionated and CyberKnife composite plans, respectively.

LESSONS

Utilization of 5-ALA and GammaTile therapy yielded clinically superior tumor debulking and effective radiotherapy dose localization with sparing of organs at risk, respectively.

Developing a 4-D Dynamic Model for GammaTile Dose Distribution

PURPOSE/OBJECTIVE(S)

GammaTile consists of Cesium-131 seeds imbedded in square 2cm tiles for intracranial resectable neoplasms. Currently, intra- and inter-tile source motion as the resection cavity evolves is not well characterized. We hypothesize that source motion is influenced by the overall tile motion which can be elucidated by 4D models of seed motion.

MATERIALS/METHODS

Our patient underwent 23 fractions of EBRT after GammaTile for glioblastoma as a combined modality approach. Individual sources were identified and assigned to tiles on the post-operative, daily cone beam, and post-radiotherapy CT scans. All imaging was registered to the day 1 post-op/implant CT to utilize the same 3D space for tracking source movement. A programming environment was used to model source distances and generate dose clouds based on the seed position to create a 4D isodose volume. These dose clouds were compared to those calculated from the day 1 post-implant static isodose volume. The statistical analysis was performed using JMP®.

RESULTS

We compared the 4D vs. static isodose volumes. The DICE score for each isodose volume was evaluated (for 30, 60, and 90 Gy the DICE scores were 0.95, 0.94, and 0.92 respectively). We found a steady decline in DICE score as the isodose line increased: DICE = -0.00065*Dose (Gy) + 0.976. Looking at the distance moved, tiles moved a mean of 5.8 mm (1.3-9.6) and appeared to remain adherent to the resection cavity wall in the first 81 days. Looking at the relative motion of the seeds within a tile, we see the tile retains a planar shape during the first 81 days and seeds move a mean of 2.2 mm (1.8-2.5) towards the center of the tile, which was a 50% contraction of the tile area. Table 1 details changes in the mean distance of source from tile center and volume occupied by all sources over time.

CONCLUSION

This modeling of the tile movement/contraction is the first reported proof of concept in an approach relating tile motion with respect to sources and cavity over time. Tiles moved a mean of 5.8 mm and shrunk in the first 81 days. Discerning both how surgical cavity healing impacts seed/tile migration and how deformation impacts the dose distribution of the radiation delivered may provide a more accurate estimate of dose received by normal structures and at-risk tumor bed.

First application of GammaTile cesium-131 brachytherapy with maximal safe resection of a glioma in a patient with limited scleroderma

The purpose of this report is to present the first documented application of GammaTile to an intra-cranial tumor of a patient with a symptomatic radiosensitive connective tissue disorder, a case where there were significant concerns with standard oncologic strategies. We hypothesized that GammaTile® (GT Medical Technologies, Tempe, Arizona, USA) would also be advantageous in the application of intra-cranial tumors in patients with conditions of increased radiosensitivity. We generated a standard external beam radiation therapy (EBRT) plan consisting of an overall 1.5 cm expansion to 59.4 Gy in 1.8 Gy fractions. Also, we developed a CyberKnife (Accuray, Sunnyvale, CA, USA) plan with a 5 mm expansion on the surgical cavity prescribed to 60 Gy in 30 fractions, to make an EBRT comparison using the same prescription volume as GammaTile. We report the first published application of GammaTile® brachytherapy to an intra-cranial malignancy in a patient with limited scleroderma. The dose delivered by GammaTile was compared to the dose that would be delivered with both typical volumes and small volumes of EBRT. The maximum dose delivered to the scar and scalp by GammaTile was reduced to half of that from other external beam techniques (~25 Gy vs. ~55 Gy). MRI imaging at 6 months and 12 months post-resection demonstrated no evidence of disease recurrence nor radiation necrosis. At the 12-month follow-up visit, the surgical scar was well-healed with no skin changes to the surrounding scalp. Dosimetrically and clinically, this report highlights the successful application of GammaTile to an intra-cranial tumor bed in a patient with scleroderma.

A SEER Database Cohort of 547 Patients with Non-Squamous Cell Carcinoma of the Penis: Clinical Characteristics and Outcomes

PURPOSE/OBJECTIVE(S)

Little research has investigated the prevalence and distribution of the diverse pathologies of non-squamous cell carcinoma (non-SCC) of the penis. Although rare in clinical practice, these cancers have become a focus of greater importance among patients, clinicians, and researchers, particularly in developing countries. The principal objective of this study was to analyze the major types of penile non-squamous cell carcinoma, elucidate common treatment pathways, and highlight outcomes including 5-year survival.

MATERIALS/METHODS

The Surveillance, Epidemiology and End Results (SEER) database was queried between 2000 to 2018 to identify a retrospective cohort of patients with penile non-SCC. Demographic information, cancer characteristics, diagnostic methods, treatments administered, and survival were investigated.

RESULTS

A total of 547 cases of penile non-SCC were included in the analysis. The most prevalent non-SCC cancers included epithelial neoplasms, not otherwise specified (15.4%), unspecified neoplasms (15.2%), basal cell neoplasms (13.9%), blood vessel tumors (13.0%), nevi and melanomas (11.7%), and ductal and lobular neoplasms (9.9%). Data for the nine most prevalent neoplasms are included in Table 1. Over half (56.7%) of patients elected to undergo surgical intervention. Patients rarely received systemic therapy (3.8%) or radiation (4.0%). Five-year survival was 35.5%. Median survival was 5.2 years (62.7 months). Patients who underwent surgery had greater annual survival for 0 to 10 years compared to those who did not have surgery. Significant differences in survival were found between patients who had regional, localized, and distant metastases (p<0.05). A significant difference in survival was found for patients married at diagnosis versus those who were unmarried at diagnosis (p<0.05). Lower survival rates were observed for patients older than 70 years.

CONCLUSION

Although less prevalent than squamous cell carcinoma, penile non-SCC encompasses a diverse set of neoplasms. Patients in this cohort had a high utilization of surgical management leading to superior outcomes compared to those not receiving surgery. Radiation is an uncommonly pursued treatment pathway. Patient demographics and socioeconomic variables such as marital status may be valuable when investigating cancer outcomes. This updated database analysis can help inform diagnosis, management, and clinical outcomes for this rare group of malignancies.

Comparison of Low Dose Rate and High Dose Rate Brachytherapy Boost Techniques in Prostate Cancer: Evaluation of Toxicity

PURPOSE/OBJECTIVE(S)

The ASCENDE-RT trial has been criticized for higher rates of chronic severe toxicity (18% genitourinary (GU)) than expected with a low dose rate (LDR) boost technique. We compared clinical outcomes of LDR and high dose rate (HDR) boost in the acute and chronic setting from a large single institution experience over a continuous 20-year period, with a focus on GU and gastrointestinal (GI) toxicity during treatment of prostate cancer.

MATERIALS/METHODS

We retrospectively reviewed patients treated with LDR boost (2003 - 2013) and HDR boost (2014 - 2018). Clinical and treatment-related prognostic factors including age, stage, androgen deprivation therapy (ADT), dosimetry details, and toxicity data were recorded. Toxicity was scored according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Multi-variable analysis (MVA) was performed to evaluate variables associated with toxicity.

RESULTS

A total of 184 men were evaluated (87 LDR and 97 HDR) with a median follow-up of 7.1 years and 4.0 years, respectively. Most patients (92% LDR and 57% HDR) received ADT in addition to BT. The median EBRT dose was 46 Gy for LDR and 45 Gy for HDR (range 25 - 50 Gy). Prostate D90% was similar at 104% and 105% in the LDR and HDR groups, respectively. Urethra D10% and Rectum V100% were both higher with LDR compared to HDR with 155% vs 119% and 0.436% vs 0.073%, respectively. Severe (grade 3+) toxicity was rare (Table 1), with 3.4% of LDR patients experiencing grade 3 chronic GU toxicity. With HDR, 3.1% and 1% of patients experienced acute and chronic grade 3 GU toxicity, respectively. Although non-severe GU toxicity (grade 1-2) was similar between groups (95% LDR vs 89% HDR, p = 0.16), LDR patients experienced more grade 2 GU events (80.5% acute; 82.8% chronic) compared to HDR patients (45.4% acute; 57.7% chronic). There were no severe GI toxicities in the acute or chronic period. Non-severe acute GI toxicity was more common with HDR, while non-severe chronic GI toxicity was more common with LDR. On MVA, acute GU toxicity (any grade) was associated with short term ADT (p = 0.01) and Urethra D10% (p < 0.05); Chronic GU toxicity (any grade) was associated with age (p = 0.09) and Prostate V150cc (p = 0.07) but not BT boost technique.

CONCLUSION

This comparative retrospective analysis of BT boost techniques reveals the overall rate of severe GU and GI toxicity to be low with both LDR and HDR. HDR boost appears to have a slightly more favorable ratio of Grade 1 to Grade 2 GU toxicity and improved urethra/rectum dosimetry. Our analysis suggests that the dosimetric advantages of HDR may deliver small reductions in GU toxicity.

Towards a multi-scale computer modeling workflow for simulation of pulmonary ventilation in advanced COVID-19

Physics-based multi-scale in silico models offer an excellent opportunity to study the effects of heterogeneous tissue damage on airflow and pressure distributions in COVID-19-afflicted lungs. The main objective of this study is to develop a computational modeling workflow, coupling airflow and tissue mechanics as the first step towards a virtual hypothesis-testing platform for studying injury mechanics of COVID-19-afflicted lungs. We developed a CT-based modeling approach to simulate the regional changes in lung dynamics associated with heterogeneous subject-specific COVID-19-induced damage patterns in the parenchyma. Furthermore, we investigated the effect of various levels of inflammation in a meso-scale acinar mechanics model on global lung dynamics. Our simulation results showed that as the severity of damage in the patient's right lower, left lower, and to some extent in the right upper lobe increased, ventilation was redistributed to the least injured right middle and left upper lobes. Furthermore, our multi-scale model reasonably simulated a decrease in overall tidal volume as the level of tissue injury and surfactant loss in the meso-scale acinar mechanics model was increased. This study presents a major step towards multi-scale computational modeling workflows capable of simulating the effect of subject-specific heterogenous COVID-19-induced lung damage on ventilation dynamics.

Survival Is Worse in Patients Completing Immunotherapy Prior to SBRT/SRS Compared to Those Receiving It Concurrently or After

Purpose/Objectives

The abscopal effect could theoretically be potentiated when combined with immunomodulating drugs through increased antigen production. The optimal dosing and schedule of radiotherapy with immunotherapy are unknown, although they are actively investigated in laboratory and clinical models. Clinical data in patients treated for metastatic disease with both modalities may guide future studies.

Materials and Methods

This is a single-institution retrospective review of all patients treated with stereotactic body radiotherapy (SBRT)/stereotactic radiosurgery (SRS) and immunomodulating therapy within 6 months before or after SBRT/SRS for metastatic cancer. Clinical and tumor characteristics were recorded, as well as SBRT/SRS details, immunotherapy details, and survival. Log-rank tests on Kaplan–Meier curves for overall survival (OS) that were calculated from the end of SBRT/SRS were used in univariate analysis and Cox proportional hazards regression for multivariate analysis.

Results

A total of 125 patients were identified who met the inclusion criteria; 70 received SBRT, and 57 received SRS. Eighty-three patients were treated for non-small cell lung cancer, 7 patients for small cell lung cancer, and 35 patients for other cancers, with the most common one being melanoma. Fifty-three percent of patients received nivolumab, 29% pembrolizumab, 13% atezolizumab, 5% other. Twenty percent received immunotherapy before SBRT/SRS, 39% during SBRT/SRS, 41% after. Eighty-six patients had died by the time of the analysis; the median OS for the whole cohort was 9.7 months. Patients who had completed immunotherapy prior to SBRT/SRS had worse OS than those who received concurrent therapy or immunotherapy after SBRT/SRS, with a difference in median OS of 3.6 months vs. 13.0 months (p = 0.010) that was retained on multivariate analysis (p = 0.011). There was no significant difference in OS between patients receiving SRS vs. SBRT (p = 0.20), sex (p = 0.53), age &gt;62 years (p = 0.76), or lung primary vs. others (p = 0.73) on univariate or multivariate analysis. When comparing before/concurrent to after/concurrent administration, there is a difference in survival with after/concurrent survival of 8.181 months and before survival of 13.010 months, but this was not significant (p = 0.25).

Conclusions

OS appears to be worse in patients who complete immunotherapy prior to SBRT/SRS compared to those receiving it concurrently or after. The design of this retrospective review may be prone to lead time bias, although the difference in median survival is longer than the 6-month window before SBRT/SRS and could only account for part of this difference. Further analysis into causes of death and toxicity and prospective studies are needed to confirm the results of this analysis.

Stereotactic Shifts During Frame-Based Image-Guided Stereotactic Radiosurgery: Clinical Measurements

PURPOSE

To determine the magnitude and reason for discrepancies between frame- and cone beam computed tomography (CBCT)-determined stereotactic coordinates, we reviewed frame-based Gamma Knife radiosurgery procedures in which CBCT was performed before treatment.

METHODS AND MATERIALS

Clinical and treatment documentation was reviewed for 150 frame placements for which stereotactic coordinates were defined via both frame and fiducials on computed tomography imaging and CBCT. Treatment planning system-reported rotational and translational differences and standard deviations (SDs) between frame-based and CBCT-based stereotactic coordinates were recorded. Potential clinical predictors for increased differences were collected. Multiple linear regressions were performed to evaluate for associations with increased translations and rotations.

RESULTS

The absolute mean of the measured pitch, yaw, and roll shifts was 0.14 degrees (range -0.71-0.63 degrees, SD 0.19 degrees), 0.16 degrees (range -0.50 to 0.83 degrees, SD 0.21 degrees), and 0.12 degrees (range 0.37-0.51 degrees, SD 0.15 degrees), respectively. The absolute mean of the measured shifts in the left-right, anteroposterior, and superior-inferior direction was 0.29 mm (range -1.29 to 0.82 mm, SD 0.35 mm), 0.24 mm (range -0.59 to 0.33 mm, SD 0.19 mm), and 0.24 mm (range -0.69 to 0.91 mm, SD 0.27 mm), respectively. Three cases (2.0%) exceeded 1 mm in translational difference, all in the left-right direction (1.05, 1.13, and 1.29 mm). Lower Karnofsky Performance Scale status was associated with greater translational differences (vector magnitude, P = .023) and rotation (pitch, P = .044; yaw, P = .002). Usage of longer total pin length (sum of all 4 fixation pin lengths) was associated with increased rotation but not with translation (P < .001 and P = .56, respectively).

CONCLUSIONS

CBCT imaging in this cohort of frame-based cases suggests that the discrepancy in stereotactic coordinates is less than 1 mm or degree in most cases. Low Karnofsky Performance Scale status and longer total pin length correlate with larger differences between frame-defined and CBCT-defined stereotactic coordinates.

Endometrial cancer in an increasingly obese population: Exploring alternative options when surgery may not cut it

OBJECTIVES

The study objectives were to describe outcomes of obese patients with early endometrial cancer following primary non-surgical treatment, assess predictors of response, and estimate the increased surgical risk for these women.

METHODS

Retrospective chart review identified women with early stage endometrial cancer at a single institution with BMI ≥ 30 kg/m2 who did not undergo surgery as primary treatment modality due to obesity and medical co-morbidities. Clinicopathologic factors were abstracted, characteristics of responders vs. non-responders compared and the National Surgical Quality Improvement Program (NSQIP) surgical risk calculator utilized to quantify surgical risks.

RESULTS

Fifty-one patients were identified, with a mean BMI of 49.0 kg/m2. The NSQIP calculator predicted a significantly higher complication rate for our cohort compared to the expected average risk for hysterectomy (18.8% vs 7.2%, p < .0001). The majority of patients were treated with radiation alone (49%), followed by hormone therapy (45.1%). Response rates were 38.1% for women treated with hormones and 63.6% in the radiation group (p = .063). No significant differences were identified between responders and non-responders with regard to NSQIP scores, BMI, co-morbidities or age. Among those with persistent or progressive disease, 87.5% responded to secondary treatment. Only one death was from cancer progression. Two individuals died following treatment complications (one surgical, one chemotherapy); the remaining twelve deaths were due to pre-existing co-morbidities.

CONCLUSIONS

Hormone and radiation therapy are both viable options for obese patients deemed to have too significant risk of surgical complications. Pursuing surgical intervention in this population may do more harm than good.

Patient-reported outcomes in head and neck cancer: prospective multi-institutional patient-reported toxicity

Purpose

Head and neck cancer is occurring in an increasingly younger patient population, with treatment toxicity that can cause significant morbidity. Using a patient guided, Internet-based survivorship care plan program, we obtained and looked at patterns of patient-reported outcomes data from survivors seeking information after treatment for head and neck cancer.

Methods

The Internet-based OncoLife and LIVESTRONG Care Plan programs were employed, which design unique survivorship care plans based on patient-reported data. Care plans created for survivors of head and neck cancer were used in this evaluation. Demographics, treatment modality, and toxicity were included in this evaluation. Toxicity was further analyzed, grouped into system-based subsets.

Results

A total of 602 care plans were created from self-identified head and neck cancer survivors, from which patient-reported outcome data were attained. A majority of patients were Caucasian (96.2%) with median age at diagnosis of 55 years, living in suburban locations (39.9%), with ~50% receiving care within 20 miles of their residence. There was an equal distribution of education levels from high school only to graduate school. The majority of patients received care through cancer centers (96.7%), with a split between academic and non-academic centers. Ninety-three percent of patients had radiation therapy as part of their treatment modality, with 70.3% having chemotherapy and 60.1% having surgery. The most common system toxicities affected the oropharynx, followed by epithelium (skin/hair/nail), and then general global health. Specifically, the most common side effects were difficulty swallowing (61.5%) and changes in skin color/texture (49.7%). One third of patients experienced hearing/tinnitus/vertigo, xerostomia, loss of tissue flexibility, or fatigue.

Conclusion

The current work demonstrates the ability to obtain patient-reported outcomes of head and neck cancer survivors through an Internet-based survivorship care plan program. For this group dysphagia and dermatitis were the most commonly reported toxicities, as was expected; however, global effects of therapy, such as fatigue, were also significant and should be addressed in future survivorship planning.

High dose-rate tandem and ovoid brachytherapy in cervical cancer: dosimetric predictors of adverse events

Background

Brachytherapy (BT) is a vital component of the curative treatment of locally advanced cervical cancer. The American Brachytherapy Society has published guidelines for high dose rate (HDR) BT with recommended dose limits. However, recent reports suggest lower doses may be needed to avoid toxicity. The purpose of this study is to investigate incidence and predictive factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following HDR intracavitary brachytherapy for locally advanced cervical cancer.

Methods

We retrospectively evaluated a cohort of patients with locally advanced cervical cancer who received CT-based HDR BT. Cumulative doses were calculated using the linear-quadratic model. Statistical analyses were used to investigate clinical and dosimetric predictors of GI and GU toxicity following HDR brachytherapy according to CTCAE v4.0 grading criteria.

Results

Fifty-six women with FIGO IB1 – IVA cervical cancer were included. The overall rate of any GU adverse event (Grade 1+) was 23.3% (n = 13) and severe adverse events (Grade 3+) was 7.1% (n = 4). Of those, the bladder equivalent dose in 2- Gray (Gy) fractions (EQD₂) D_2cc was ≥80 for three of the four patients. The overall rate of any GI adverse event was 26.8% (n = 15) and the rate of severe adverse events was 14.3% (n = 8). Of those, six of the eight patients had a rectal EQD₂ D_2cc ≥ 65 Gy and seven patients had a sigmoid D2cc ≥ 65 Gy. Amongst clinically meaningful factors for development of adverse events (i.e. diabetes, smoking status, ovoid size, and treatment duration), there were no statistically significant prognostic factors identified.

Conclusions

Severe adverse events are observed even with adherence to current ABS guidelines. In the era of recent multi-institutional study results, our data also supports more stringent dosimetric goals. We suggest cumulative D2cc dose limits of: less than 80 Gy for the bladder and less than 65 Gy for the rectum and sigmoid.

Spatial shifts in frame-based Gamma Knife radiosurgery: A case for cone beam CT imaging as quality assurance using the Gamma Knife® Icon™

BACKGROUND

Cone beam CT (CBCT) imaging has been integrated into the most recent version of the Leksell Gamma Knife for the primary purpose to facilitate fractionated therapy.

CASE DESCRIPTION

This case study presents three patients where the CBCT system of the Gamma Knife Icon discovered potentially clinically significant frame shifts. In each case, patients were imaged with volumetric MR prior to stereotactic frame placement. Immediately following frame placement, diagnostic stereotactic CT imaging was acquired with a stereotactic indicator box attached to the frame. Following treatment planning and immediately before radiosurgery, a CBCT was acquired using the on-board imaging functionality of the Gamma Knife Icon, which provides a registration of the patient's anatomy to stereotactic space independent of that provided by the stereotactic frame/fiducials. Co-registration of the CT and CBCT provides an estimate of the difference between these two estimates of stereotactic coordinates. The vector magnitudes of the differences measured at the center of stereotactic space were 0.93mm, 2.64mm and 2.18 mm for Case 1, Case 2 and Case 3 respectively.

CONCLUSIONS

Use of the CBCT functionality of the Gamma Knife Icon to verify the consistency of frame placement can prevent clinically significant targeting errors due to frame slippage or frame adapter mounting errors, and allows any required adjustments to be made without interrupting the overall treatment workflow.

Evaluation of outcomes after stereotactic radiosurgery for pilocytic astrocytoma

Pilocytic astrocytomas are rare intracranial gliomas that are typically treated with surgical extirpation. Our aim was to report the radiologic and clinical outcomes of patients treated with stereotactic radiosurgery (SRS) for pilocytic astrocytoma in the primary and salvage setting. Patients with pilocytic astrocytoma treated at a single institution with SRS from 1990 to 2015 were reviewed. Patient, disease, and treatment characteristics were collected and overall survival, local control, and toxicity were evaluated. Twenty-eight consecutive patients (12 females and 16 males) with a median age of 17.4 years at SRS were identified. Overall, 46% of patients were treated with SRS as part of the initial treatment course after biopsy or subtotal resection, and the remainder as a salvage therapy. The most common location was the cerebellum (28%) followed by brainstem and basal ganglia (21 and 18%, respectively). Four patients received prior external beam radiation therapy (14%). Median tumor volume was 1.84 cc (0.19-15.94 cc), and 39% had a cystic component at SRS. Prescription dose ranged from 4 to 20 Gy (median 16 Gy) to a median isodose line of 50% (range 30-100%). With a median follow-up of 5.2 years (0.3-17.1 years), all patients remained alive at last follow-up. Two patients demonstrated evidence of local radiographic progression at last follow-up (7%). No toxicity could be directly attributed to SRS. In this SRS series, durable tumor control was achieved in 93% of patients with pilocytic astrocytoma, although continued follow up will be important giving the natural history of this disease. As demonstrated, SRS is an appropriate technique in the primary and recurrent treatment of pilocytic astrocytoma that offers favorable disease control and infrequent clinical toxicity.

Systematic Review of Focal Prostate Brachytherapy and the Future Implementation of Image-Guided Prostate HDR Brachytherapy Using MR-Ultrasound Fusion

Prostate cancer is the most common malignancy found in North American and European men and the second most common cause of cancer related death. Since the practice of PSA screening has become common the disease is most often found early and can have a long indolent course. Current definitive therapy treats the whole gland but has considerable long-term side effects. Focal therapies may be able to target the cancer while decreasing dose to organs at risk. Our objective was to determine if focal prostate brachytherapy could meet target objectives while permitting a decrease in dose to organs at risk in a way that would allow future salvage treatments. Further, we wanted to determine if focal treatment results in less toxicity. Utilizing the Medline repository, dosimetric papers comparing whole gland to partial gland brachytherapy and clinical papers that reported toxicity of focal brachytherapy were selected. A total of 9 dosimetric and 6 clinical papers met these inclusion criteria. Together, these manuscripts suggest that focal brachytherapy may be employed to decrease dose to organs at risk with decreased toxicity. Of current technology, image-guided HDR brachytherapy using MRI registered to transrectal ultrasound offers the flexibility and efficiency to achieve such focal treatments.