Clinical and radiological effects of Bevacizumab for the treatment of radionecrosis after stereotactic brain radiotherapy.

PURPOSE: The purpose of this multicenter retrospective study was to analyze the clinical and radiological effects of bevacizumab (BV) on radionecrosis (RN) that developed after stereotactic radiotherapy (SRT) for brain metastasis. METHODS: Forty patients with SRT related symptomatic brain RN treated in 10 radiation oncology centers were analyzed. The clinical response to BV treatment was categorized as follows: complete (no additional treatment required), partial (requiring either steroids or repeat BV), and unresponsive (requiring surgery). The radiological features of brain RN were analyzed in 10 patients whose serial MRI scans were available after corticosteroid and BV treatments. RESULTS: BV was used as a first line treatment in 11 (27.5%) and as a second line treatment in 29 (72.5%) of patients. The neurological symptoms regressed in 77.5% of patients after treatment with BV (45% complete response, 32.5% partial response). The median edema volume increased from 75.9 cc (range: 5.9-125.8 cc) at RN to 113.65 cc (range: 1.5-382.1 cc) after use of corticosteroids, representing a rate of 39.8% increase (p = 0.074). However, after BV treatment the median volume of edema decreased to 19.5 cc (range: 0-163.3 cc) which represents a difference of 62.2% (p = 0.041) from RN. CONCLUSION: The use of BV caused clinical response rate of 77.5% and a good radiological response in corticosteroid unresponsive patients. The role of BV should be further investigated in prospective studies.

A Rare Case of BRAF-mutated Metastatic Pleomorphic Xanthoastrocytoma Patient who Developed Radiodermatitis After Receiving Anti-BRAF Treatment.

Pleomorphic xanthoastrocytoma (PXA) is a rare type of grade 2 or 3 brain tumor that usually occurs in children and young adults. The standard treatment for PXA is maximally safe resection, usually with adjuvant radiation therapy, for high-grade tumors. BRAF V600E mutation is one of the most common molecular alterations in these tumors, with nearly 70% of cases carrying this mutation. Although BRAF inhibitors have shown promise in treating progressive or refractory disease, their use has been associated with various adverse effects, including radiodermatitis, which is a relatively common complication. This paper presents a case of a 16-year-old male patient with BRAF-mutated metastatic PXA, who developed mild radiodermatitis after receiving BRAF inhibitors with concurrent radiation therapy.

Intraoperative sonographic guidance for intracavitary brachytherapy of cervical cancer.

BACKGROUND: To describe the role and benefits of intraoperative sonographic (US) guidance in intracavitary brachytherapy of cervical cancer. METHODS: The data of 142 patients who received tandem-based intracavitary brachytherapy for cervical cancer between January 2010 and June 2015 were retrospectively reviewed. US guidance was carried out for tandem selection and appropriate application. The complications and applicator conformity were assessed with planning CT. RESULTS: Intracavitary brachytherapy was performed under US guidance for 412 insertions in 113 consecutive patients with cervical cancer. Before we started to use US guidance, applications were done in 29 patients: uterine perforation occurred in two patients (6.9%), the tandem length was short in two patients (6.9%), the tandem length was long in four patients (13.8%), and tandem was in myometrium in three patients (10.3%). We then decided to use US guidance routinely. With US guidance, only 1 of 113 patients had uterine perforation (0.9%), tandem length was short in only one patient (0.9%), and tandem was in myometrium in one patient (0.9%). CONCLUSIONS: Real-time US provided safe and effective guidance for intracavitary brachytherapy of cervical cancer resulting in decreased rates of perforations and misplacement of applicators. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 46:8-13, 2018.

Dosimetric comparison of stereotactic MR-guided radiation therapy (SMART) and HDR brachytherapy boost in cervical cancer.

PURPOSE: The standard of care in locally advanced cervical cancer (LACC) is concomitant chemoradiotherapy followed by high-dose-rate brachytherapy (HDR-BT). Although previous studies compared HDR-BT with stereotactic body radiotherapy (SBRT), there is scarce data regarding the dosimetric outcomes of stereotactic MR-guided adaptive radiation therapy (SMART) boost in lieu of HDR-BT. METHODS AND MATERIALS: In this single-institutional in-silico comparative study, LACC patients who were definitively treated with external beam radiotherapy followed by HDR-BT were selected. Target volumes and organs at risk (OARs) were delineated in MRI and HDR-planning CT. An HDR-BT and a SMART boost plan were generated with a prescribed dose of 28 Gy in four fractions for all patients. The HDR-BT and SMART boost plans were compared in regard to target coverage as well OARs doses. RESULTS: Mean EQD2 D90 to HR-CTV and IR-CTV for HDR-BT plans were 89.7 and 70.5 Gy, respectively. For SMART, the mean EQD2 D90 to HR-PTV, HR-CTV, and IR-CTV were 82.9, 95.4, and 70.2 Gy, respectively. The mean D2cc EQD2 of bladder, rectum, and sigmoid colon for HDR-BT plans were 86.4, 70.7, and 65.7 Gy, respectively. The mean D2cc EQD2 of bladder, rectum, and sigmoid colon for SMART plans were 81.4, 70.8, and 73.6 Gy, respectively. All dose constraints in terms of target coverage and OARs constraints were met for both HDR-BT and SMART plans. CONCLUSIONS: This dosimetric study demonstrates that SMART can be applied in cases where HDR-BT is not available or ineligible with acceptable target coverage and OAR sparing. However, prospective clinical studies are needed to validate these results.

Factors influencing local control after MR-guided stereotactic body radiotherapy (MRgSBRT) for adrenal metastases.

Purpose: Stereotactic body radiotherapy (SBRT) is an effective treatment for adrenal gland metastases, but it is technically challenging and there are concerns about toxicity. We performed a multi-institutional pooled retrospective analysis to study clinical outcomes and toxicities after MR-guided SBRT (MRgSBRT) using for adrenal gland metastases. Methods and Materials: Clinical and dosimetric data of patients treated with MRgSBRT on a 0.35 T MR-Linac at 11 institutions between 2016 and 2022 were analyzed. Local control (LC), local progression-free survival (LPFS), distant progression-free survival (DPFS) and overall survival (OS) were estimated using Kaplan-Meier method and log-rank test. Results: A total of 255 patients (269 adrenal metastases) were included. Metastatic pattern was solitary in 25.9 % and oligometastatic in 58.0 % of patients. Median total dose was 45 Gy (range, 16-60 Gy) in a median of 5 fractions, and the median BED10 was 100 Gy (range, 37.5-132.0 Gy). Adaptation was done in 87.4 % of delivered fractions based on the individual clinicians' judgement. The 1- and 2- year LPFS rates were 94.0 % (95 % CI: 90.7-97.3 %) and 88.3 % (95 % CI: 82.4-94.2 %), respectively and only 2 patients (0.8 %) experienced grade 3 + toxicity. No local recurrences were observed after treatment to a total dose of BED10 > 100 Gy, with single fraction or fractional dose of > 10 Gy. Conclusions: This is a large retrospective multi-institutional study to evaluate the treatment outcomes and toxicities with MRgSBRT in over 250 patients, demonstrating the need for frequent adaptation in 87.4 % of delivered fractions to achieve a 1- year LPFS rate of 94 % and less than 1 % rate of grade 3 + toxicity. Outcomes analysis in 269 adrenal lesions revealed improved outcomes with delivery of a BED10 > 100 Gy, use of single fraction SBRT and with fraction doses > 10 Gy, providing benchmarks for future clinical trials.

Psychosocial Impact of the War in Ukraine on Pediatric Cancer Patients and Their Families Receiving Oncological Care Outside Their Country at the Onset of Hostilities.

Psychosocial care of pediatric cancer patients and their families is as critical as the medical and surgical components of their therapies. Strains on family communication and structure and financial need are linked to poorer psychological outcomes for both patients and families. It is critical that children remain as connected as possible to their communities and extended families during therapy. For Ukrainian pediatric cancer patients receiving care outside of their nation's borders on February 24, 2022, the Russian invasion of Ukraine compounded these problems. Based on conversations with patients and parents, we evaluated the psychosocial impact of war on pediatric Ukrainian cancer patients and their families who had left their country before the onset of the conflict to undergo treatment of pediatric malignancies at our medical center. These families shared with us the problems they have experienced after the Russian invasion of Ukraine. Their concerns can be summarized in 4 categories: (1) emotional stress experienced by the patients, families and relatives related to the dangers of war; (2) difficulties in obtaining previous hospital records in Ukraine; (3) medical expenses; and (4) uncertainty regarding the patient's and their family's future and the ability of the children to ever return to their homes. Psychosocial distress relating to the violence of war will hopefully pass in near future, but our pediatric patients and their families will continue to face stressors related to displacement and financial concerns for some time to come.

Magnetic Resonance Imaging-Guided Radiation Therapy for Early-Stage Gastric Mucosa-Associated Lymphoid Tissue Lymphoma.

Lymphoid neoplasia derived from mucosa-associated lymphoid tissue (MALT; also abbreviated as MALToma) is most commonly seen in the stomach. Radiotherapy (RT) is indicated in early-stage disease as a standard of care. With the advent of RT techniques, large field irradiation was replaced by involved site and involved field approaches. Magnetic resonance imaging-guided online adaptive RT (MRgRT) has the advantage of better soft tissue visualization, adaptive planning before each fraction, and online tumor tracking during treatment; hence, it could be a safe and effective choice for gastric MALToma patients. Herein, we investigated the interfractional changes in target and the impact of MRgRT on daily dosimetry in a gastric MALToma case. A patient diagnosed with MALToma who failed to respond to antibacterial treatment was referred to our clinic for RT. He was found to be suitable for MRgRT. We treated the patient with MRgRT in 20 fractions to a total dose of 30 Gy. Reoptimized adaptive plans were generated before each fraction since the coverages of the original plan were inadequate in each fraction. The patient showed good compliance and tolerated the treatment well. To our knowledge, this is the first documented case of a gastric MALToma treated with MRgRT. MRgRT is safe and feasible for this patient group with improved target coverage using small planning target volume margins. Without online adaptive planning, the target coverages would be inadequate and we would risk surrounding tissues to get higher doses.

Magnetic Resonance Image-Guided Hypofractionated Ablative Radiation Therapy for Hepatocellular Carcinoma With Tumor Thrombus Extending to the Right Atrium.

Hepatocellular carcinoma (HCC) presenting with tumor thrombus (TT) and inferior vena cava (IVC)/right atrium (RA) infringement point to an advanced-stage disease that is deemed inoperable. Stereotactic body radiotherapy is an emerging treatment option for this group of patients with promising outcomes in recent studies that are comparable to conventional treatment methods, namely, transarterial chemoembolization and transarterial radioembolization. Here, we report a case of HCC with RA extension through the IVC. The patient was referred to our clinic for treatment options, and he was found suitable for magnetic resonance imaging-guided radiotherapy (MRgRT). We treated the patient with MRgRT in five fractions to a total dose of 40 Gray. The tumor was tracked during the treatment sessions, and adaptive treatment planning was performed before each fraction. The patient tolerated the treatment well with no acute grade 3-4 toxicities. The last follow-up showed that the patient had a complete biochemical response and is now a candidate for an orthotopic liver transplant. To our knowledge, this report is the first to document the MRgRT treatment of an HCC with TT and RA extension. MRgRT is safe and feasible for this patient group and can be an effective bridging therapy for liver transplants.

Magnetic Resonance Imaging-Guided Online Adaptive Lattice Stereotactic Body Radiotherapy in Voluminous Liver Metastasis: Two Case Reports.

Lattice Radiotherapy (LRT) is a technique in which heterogeneous doses are delivered to the target so large tumors can have optimal doses of radiation without compromising healthy tissue sparing. To date, case reports and case series documented its application for bulky tumors mainly in the pelvic region. LRT not only provides dosimetric advantages but also promotes tumor control by triggering some radiobiological and immunological pathways. We report two cases of giant liver metastases for whom other treatment options were not suitable. We treated both patients with Magnetic Resonance Image-Guided Radiotherapy (MRgRT) with online adaptive LRT (OALRT) technique. Adaptive plans were generated before each fraction. Tumors were observed to have regressed interfractionally so the location and number of spheres were adapted to tumor size and daily anatomy of the surrounding organs at risk (OAR). Both patients had good treatment compliance without any Grade 3+ side effects. They are both under follow-up and report improvement. By reporting the first application of OALRT by using MRgRT in liver metastases, we show that MRgRT is a promising modality for LRT technique with better target and OAR visualization as well as online adaptive planning before each fraction according to the daily anatomy of the patient.

Multi-Institutional Outcomes of Stereotactic Magnetic Resonance Image Guided Adaptive Radiation Therapy With a Median Biologically Effective Dose of 100 Gy10 for Non-bone Oligometastases.

Purpose: Randomized data show a survival benefit of stereotactic ablative body radiation therapy in selected patients with oligometastases (OM). Stereotactic magnetic resonance guided adaptive radiation therapy (SMART) may facilitate the delivery of ablative dose for OM lesions, especially those adjacent to historically dose-limiting organs at risk, where conventional approaches preclude ablative dosing. Methods and Materials: The RSSearch Registry was queried for OM patients (1-5 metastatic lesions) treated with SMART. Freedom from local progression (FFLP), freedom from distant progression (FFDP), progression-free survival (PFS), and overall survival (LS) were estimated using the Kaplan-Meier method. FFLP was evaluated using RECIST 1.1 criteria. Toxicity was evaluated using Common Terminology Criteria for Adverse Events version 4 criteria. Results: Ninety-six patients with 108 OM lesions were treated on a 0.35 T MR Linac at 2 institutions between 2018 and 2020. SMART was delivered to mostly abdominal or pelvic lymph nodes (48.1%), lung (18.5%), liver and intrahepatic bile ducts (16.7%), and adrenal gland (11.1%). The median prescribed radiation therapy dose was 48.5 Gy (range, 30-60 Gy) in 5 fractions (range, 3-15). The median biologically effective dose corrected using an alpha/beta value of 10 was 100 Gy10 (range, 48-180). No acute or late grade 3+ toxicities were observed with median 10 months (range, 3-25) follow-up. Estimated 1-year FFLP, FFDP, PFS, and OS were 92.3%, 41.1%, 39.3%, and 89.6%, respectively. Median FFDP and PFS were 8.9 months (95% confidence interval, 5.2-12.6 months) and 7.6 months (95% confidence interval, 4.5-10.6 months), respectively. Conclusions: To our knowledge, this represents the largest analysis of SMART using ablative dosing for non-bone OM. A median prescribed biologically effective dose of 100 Gy10 resulted in excellent early FFLP and no significant toxicity, likely facilitated by continuous intrafraction MR visualization, breath hold delivery, and online adaptive replanning. Additional prospective evaluation of dose-escalated SMART for OM is warranted.

Magnetic resonance image-guided stereotactic body radiation therapy for liver rhabdoid tumor in infancy: A case report.

Extracranial malignant rhabdoid tumors are rare and aggressive tumors that typically occur in the pediatric age group and have a poor prognosis. Herein, we report a case of a one year and five months old male infant who was referred with the diagnosis of malignant rhabdoid tumor of the liver. Magnetic resonance guided stereotactic body radiotherapy was administered with concomitant chemotherapy. Treatment was well tolerated with no severe acute side effects. A 40.8% volumetric reduction of the tumor was observed at the last fraction of MR guided radiotherapy.

Magnetic resonance image-guided hypofractionated ablative radiation therapy for extrahepatic cholangiocarcinoma: Plan adaptation in changing anatomy.

Extrahepatic cholangiocarcinoma is an aggressive malignancy of biliary duct epithelium which typically has a poor prognosis. Although surgical resection improves overall survival, many patients are deemed medically inoperable or have unresectable tumors. Herein, we report a case of an 84-year-old Caucasian male who was diagnosed with medically inoperable extrahepatic cholangiocarcinoma. Magnetic resonance image-guided hypofractionated ablative radiotherapy was administered which has the advantages of superior soft tissue resolution, better visualization of the target and organ at risk, daily online adaptive planning and continuous cine MR tracking of the target during irradiation. Concomitant chemotherapy was used. On the first fraction the patient presented with a broken arm that forced the patient take a treatment position much different than the one used for simulation CT and planning. The patient was able to finish the treatment without the need of another simulation by adapting the plan according to the new anatomy. The patient is being followed up until today and is alive with no evidence of disease.

Stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of liver metastases in oligometastatic patients: initial clinical experience.

PURPOSE: We aimed to present our initial clinical experience on the implementation of a stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of liver metastases in oligometastatic disease. MATERIALS AND METHODS: Twenty-one patients (24 lesions) with liver metastasis treated with SMART were included in this retrospective study. Step-and-shoot intensity-modulated radiotherapy technique was used with daily plan adaptation. During delivery, real-time imaging was used by acquiring planar magnetic resonance images in sagittal plane for monitoring and gating. Acute and late toxicities were recorded both during treatment and follow-up visits. RESULTS: The median follow-up time was 11.6 months (range, 2.2 to 24.6 months). The median delivered total dose was 50 Gy (range, 40 to 60 Gy); with a median fraction number of 5 (range, 3 to 8 fractions) and the median fraction dose was 10 Gy (range, 7.5 to 18 Gy). Ninety-three fractions (83.7%) among 111 fractions were re-optimized. No patients were lost to follow-up and all patients were alive except one at the time of analysis. All of the patients had either complete (80.9%) or partial (19.1%) response at irradiated sites. Estimated 1-year overall survival was 93.3%. Intrahepatic and extrahepatic progression-free survival was 89.7% and 73.5% at 1 year, respectively. There was no grade 3 or higher acute or late toxicities experienced during the treatment and follow-up course. CONCLUSION: SMART represents a new, noninvasive and effective alternative to current ablative radiotherapy methods for treatment of liver metastases in oligometastatic disease with the advantages of better visualization of soft tissue, real-time tumor tracking and potentially reduced toxicity to organs at risk.

Magnetic resonance image-guided adaptive stereotactic body radiotherapy for prostate cancer: preliminary results of outcome and toxicity.

OBJECTIVE: Using moderate or ultra-hypofractionation, which is also known as stereotactic body radiotherapy (SBRT) for treatment of localized prostate cancer patients has been increased. We present our preliminary results on the clinical utilization of MRI-guided adaptive radiotherapy (MRgRT) for prostate cancer patients with the workflow, dosimetric parameters, toxicities and prostate-specific antigen (PSA) response. METHODS: 50 prostate cancer patients treated with ultra-hypofractionation were included in the study. Treatment was performed with intensity-modulated radiation therapy (step and shoot) technique and daily plan adaptation using MRgRT. The SBRT consisted of 36.25 Gy in 5 fractions with a 7.25 Gy fraction size. The time for workflow steps was documented. Patients were followed for the acute and late toxicities and PSA response. RESULTS: The median follow-up for our cohort was 10 months (range between 3 and 29 months). The median age was 73.5 years (range between 50 and 84 years). MRgRT was well tolerated by all patients. Acute genitourinary (GU) toxicity rate of Grade 1 and Grade 2 was 28 and 36%, respectively. Only 6% of patients had acute Grade 1 gastrointestinal (GI) toxicity and there was no Grade ≥ 2 GI toxicity. To date, late Grade 1 GU toxicity was experienced by 24% of patients, 2% of patients experienced Grade 2 GU toxicity and 6% of patients reported Grade 2 GI toxicity. Due to the short follow-up, PSA nadir has not been reached yet in our cohort. CONCLUSION: In conclusion, MRgRT represents a new method for delivering SBRT with markerless soft tissue visualization, online adaptive planning and real-time tracking. Our study suggests that ultra-hypofractionation has an acceptable acute and very low late toxicity profile. ADVANCES IN KNOWLEDGE: MRgRT represents a new markerless method for delivering SBRT for localized prostate cancer providing online adaptive planning and real-time tracking and acute and late toxicity profile is acceptable.

Radiotherapy in the treatment of extracranial hemangiopericytoma/solitary fibrous tumor: Study from the Rare Cancer Network.

BACKGROUND AND PURPOSE: The role of radiotherapy (RT) in the treatment of hemangiopericytoma/solitary fibrous tumor (HPC/SFT) is still under debate. We aimed at investigating whether radiotherapy can improve the results in patients operated for extracranial HPC/SFT. MATERIALS AND METHODS: Data from patients with HPC/SFT, treated from 1982 to 2012, were retrospectively reviewed within the Rare Cancer Network framework. Actuarial local control (LC), disease-free survival (DFS), metastasis-free survival (MFS) and overall survival (OS) were calculated with Kaplan-Meyer method. Patient and tumor parameters were analyzed by univariate and multivariate analysis. RESULTS: Of 114 HPC/SFT, 58 (50.9%) occurred in the extremities/superficial trunk and 56 (49.1%) in intra-thoracic/retroperitoneum. Seventy-eight patients (68.4%) underwent surgery only (Sx), and 36 (31.6%) Sx and RT (Sx + RT). Median RT dose was 60 Gy (range 45-68.4 Gy) in 1.6-2.2 Gy fractions. In the extremities/superficial trunk group of patients, actuarial 5-year LC rates were 50.4% after Sx and 91.6% after Sx + RT (p < 0.0001) for LC, and 50.4% after Sx and 83.1% after Sx + RT (p = 0.008) for DFS. In the intra-thoracic/retroperitoneum group of patients, actuarial 5-year rates were 89.3% after Sx and 77.8% after Sx + RT (p = 0.99) for LC, and 73.8% after Sx and 77.8% after Sx + RT (p = 0.93) for DFS. At multivariate analysis, the addition of RT resulted in better LC and DFS in the whole series. The advantage was confirmed for LC in the group of patients affected by extremity/superficial trunk tumors. CONCLUSION: Addition of RT to Sx could improve the prognosis, in terms of LC and DFS, essentially in patients with extremities/superficial trunk tumor locations.

Primary extranodal lymphoma of the glands. Literature review and options for best practice in 2019.

Primary extranodal non-Hodgkin's lymphomas (EN-NHL) are a heterogeneous group of malignancies that involve numerous entities with significant difference in terms of tumor site locations, prognostic factors, biology expression, and therapeutic options. In the literature, many EN-NHL types were reported from limited series which only allowed narrow views for elucidating prognostic factors and defining the role of loco-regional therapies in the era of new systemic and biologically targeted therapies. The Rare Cancer Network (RCN), an international multidisciplinary consortium, has published a number of reports on several EN-NHL sites which included many gland locations. In this review, we will focus on the recent literature for a selected number of EN-NHL types in both exocrine and endocrine gland locations. We aim to provide renewed and clear messages for the best practice in 2019 for diagnosis, histopathology, treatments, and also their prognostic implications. We believe that better understanding of molecular and genetic characteristics of these particular diseases is crucial for an appropriate management in the era of personalized treatment developments.

Treatment outcome and prognostic factors for adult patients with medulloblastoma: The Rare Cancer Network (RCN) experience.

BACKGROUND AND PURPOSE: The optimal treatment for adults with newly diagnosed medulloblastoma (MB) has not been defined. We report a large series of cases from the Rare Cancer Network. MATERIAL AND METHODS: Thirteen institutions enrolled 206 MB patients who underwent postoperative radiotherapy (RT) between 1976 and 2014. Log-rank univariate and Cox-modeled multivariate analyses were used to analyze data collected. RESULTS: Median patient age was 29 years; follow-up was 31 months. All patients had the tumor resected; surgery was complete in 140 (68%) patients. Postoperative RT was given in 202 (98%) patients, and 94% received craniospinal irradiation (CSI) and, usually, a posterior fossa boost. Ninety-eight (48%) patients had chemotherapy, mostly cisplatin and vincristine-based. The 10-year local control, overall survival, and disease-free survival rates were 46%, 51%, and 38%, respectively. In multivariate analyses, Karnofsky Performance Status (KPS) ≥80 and CSI were significant for disease-free and overall survival (P ≤ .04 for all); receiving chemotherapy and KPS ≥80 correlated with better local-control rates. CONCLUSIONS: Patients with high KPS who received CSI had better rates of disease-free and overall survival. Chemotherapy was associated with better local control. These results may serve as a benchmark for future studies designed to improve outcomes for adults with medulloblastoma.

Computed tomography based evaluation of prostatic fiducial marker migration between the periods of insertion and simulation.

OBJECTIVE: The aim of this study was to determine whether significant fiducial marker migration occurs between the periods of prostatic marker insertion and computed tomography (CT) performed for radiotherapy planning and if a waiting period is necessary. MATERIAL AND METHODS: Thirty-nine patients with prostate adenocarcinoma underwent fiducial marker insertion before radiotherapy between June 2013 and December 2015. Three markers were inserted by one radiologist under the guidance of transrectal ultrasonography. All patients underwent CT three hours after insertion to confirm the number and position of fiducial markers. Radiotherapy planning CT was performed on an average of 11 days (range 7-20) after insertion. CT images were imported into treatment planning system to analyze the position of fiducial markers. Point- based marker match algorithm was used to find the distance of marker migration. The mean and maximum distances between each fiducial markers were calculated. RESULTS: The mean distance of migration was 1.029±0.42 mm (range 0.23-1.93 mm) and the maximum distance was 1.361±0.59 mm (range 0.25-2.74 mm). The distance of marker migration was not statistically significant for the groups organized according to the timing of marker insertion, prostate volume, patient age, prostate specific antigen level and Gleason score. CONCLUSION: According to our results significant fiducial marker migration did not occur during the interval between insertion and treatment planning CT. It should be taken into consideration that performing simulation on the same day as marker insertion might prevent increased cost and delayed radiation therapy by saving the patients from extra visits to the clinic.