Hee Chul Park

The first private-hospital based proton therapy center in Korea; status of the Proton Therapy Center at Samsung Medical Center

Purpose The purpose of this report is to describe the proton therapy system at Samsung Medical Center (SMC-PTS) including the proton beam generator, irradiation system, patient positioning system, patient position verification system, respiratory gating system, and operating and safety control system, and review the current status of the SMC-PTS. Materials and Methods The SMC-PTS has a cyclotron (230 MeV) and two treatment rooms: one treatment room is equipped with a multi-purpose nozzle and the other treatment room is equipped with a dedicated pencil beam scanning nozzle. The proton beam generator including the cyclotron and the energy selection system can lower the energy of protons down to 70 MeV from the maximum 230 MeV. Results The multi-purpose nozzle can deliver both wobbling proton beam and active scanning proton beam, and a multi-leaf collimator has been installed in the downstream of the nozzle. The dedicated scanning nozzle can deliver active scanning proton beam with a helium gas filled pipe minimizing unnecessary interactions with the air in the beam path. The equipment was provided by Sumitomo Heavy Industries Ltd., RayStation from RaySearch Laboratories AB is the selected treatment planning system, and data management will be handled by the MOSAIQ system from Elekta AB. Conclusion The SMC-PTS located in Seoul, Korea, is scheduled to begin treating cancer patients in 2015.

Dosimetric effects of multileaf collimator leaf width on intensity-modulated radiotherapy for head and neck cancer.

PURPOSEnThe authors evaluated the effects of multileaf collimator (MLC) leaf width (2.5 vs. 5 mm) on dosimetric parameters and delivery efficiencies of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) for head and neck (H&N) cancers.nnnMETHODSnThe authors employed two types of mock phantoms: large-sized head and neck (LH&N) and small-sized C-shape (C-shape) phantoms. Step-and-shoot IMRT (S&S_IMRT) and VMAT treatment plans were designed with 2.5- and 5.0-mm MLC for both C-shape and LH&N phantoms. Their dosimetric characteristics were compared in terms of the conformity index (CI) and homogeneity index (HI) for the planning target volume (PTV), the dose to organs at risk (OARs), and the dose-spillage volume. To analyze the effects of the field and arc numbers, 9-field IMRT (9F-IMRT) and 13-field IMRT (13F-IMRT) plans were established for S&S_IMRT. For VMAT, single arc (VMAT1) and double arc (VMAT2) plans were established. For all plans, dosimetric verification was performed using the phantom to examine the relationship between dosimetric errors and the two leaf widths. Delivery efficiency of the two MLCs was compared in terms of beam delivery times, monitor units (MUs) per fraction, and the number of segments for each plan.nnnRESULTSn2.5-mm MLC showed better dosimetric characteristics in S&S_IMRT and VMAT for C-shape, providing better CI for PTV and lower spinal cord dose and high and intermediate dose-spillage volume as compared with the 5-mm MLC (p < 0.05). However, no significant dosimetric benefits were provided by the 2.5-mm MLC for LH&N (p > 0.05). Further, beam delivery efficiency was not observed to be significantly associated with leaf width for either C-shape or LH&N. However, MUs per fraction were significantly reduced for the 2.5-mm MLC for the LH&N. In dosimetric error analysis, absolute dose evaluations had errors of less than 3%, while the Gamma passing rate was greater than 95% according to the 3%/3 mm criteria. There were no significant differences in dosimetric error between the 2.5- and 5-mm MLCs.nnnCONCLUSIONSnAs compared with MLC of 5-mm leaf widths, MLC with finer leaf width (2.5-mm) can provide better dosimetric outcomes in IMRT for C-shape. However, the MLC leaf width may only have minor effects on dosimetric characteristics in IMRT for LH&N. The results of the present study will serve as a useful assessment standard when assigning or introducing equipment for the treatment of H&N cancers.

Predictors and patterns of recurrence after curative liver resection in intrahepatic cholangiocarcinoma, for application of postoperative radiotherapy: a retrospective study

BackgroundThe majority of patients with intrahepatic cholangiocarcinoma (IHCC) who undergo complete tumor resection subsequently develop tumor recurrence. The objectives of this study were to determine the risk factors for IHCC recurrence after curative (R0) liver resection and to identify the feasibility about postoperative adjuvant radiation therapy (RT).MethodsWe retrospectively reviewed patients who underwent liver resection for IHCC between April 1995 and December 2012 at Samsung Medical Center. Cox regression analysis was performed to determine risk factors of recurrence. Patients with a recurrence in remnant liver within 2xa0cm from the resection margin, with or without locoregional lymph node (LN) metastases, were considered as potential RT candidates. Center-of-mass (COM) distances between the recurrent cancers and the cut surface were measured with MATLAB.ResultsWe included 153 out of 198 patients who underwent partial liver resection for IHCC. About two thirds (nu2009=u200993, 60.8xa0%) of patients developed recurrent disease. The median recurrence-free survival (RFS) was 14xa0months (range, 0–204). Tumor size ≥4.0xa0cm, LN metastasis and multiple tumors were significant predictors of IHCC recurrence on multivariate analysis. Tumor size ≥5.0xa0cm was the only factor associated with recurrence beyond the RT field in patients with recurrence. Among 93 patients with recurrence, 16 (17.2xa0%) patients were recurred in the RT field.ConclusionAfter curative resection in IHCC, more than 60xa0% of patients recurred, and among recurred patients, 17.2xa0% were recurred within the RT field. Consequently, for control of locoregional recurrence, adjuvant RT could be carefully considered in patients with recurrence factors. Especially, patients with a tumor size larger than 5xa0cm should be judiciously selected for adjuvant RT.

Clinical impact of combined transarterial chemoembolization and radiotherapy for advanced hepatocellular carcinoma with portal vein tumor thrombosis: An external validation study

PURPOSEnTo evaluate the relationship between portal vein tumor thrombosis (PVTT) response and clinical outcomes in patients with hepatocellular carcinoma (HCC) treated with transarterial chemoembolization followed by radiotherapy (TACE-RT).nnnMATERIALS AND METHODSnThe study enrolled 329 patients in the training set and 179 patients in the validation set. All patients who were treated with TACE-RT from 2002 to 2008 and satisfied the inclusion criteria were enrolled in the study. The median follow-up period was 11.7 months (range, 1.6-108.6) in the training set and 11.9 months (range, 1.7-105.1) in the validation set.nnnRESULTSnAfter TACE-RT, PVTT response was complete or partial in 32 (9.7%) and 134 (40.7%) patients of the training set and in 18 (10.1%) and 96 (53.6%) patients in the validation set, respectively. Failure to obtain PVTT response was significantly related with elevated post-treatment Child-Pugh score (P<0.001). Furthermore, progression-free survival was significantly related with PVTT response (P<0.001, hazard ratio 0.33, 95% confidence interval 0.25-0.42) in multivariate analysis. In receiver-operating characteristics analysis of 1-year progression prediction, the PVTT response showed an area under the curve of 0.74. Most of the findings were successfully reproduced in the independent external validation set.nnnCONCLUSIONSnPositive PVTT response was closely associated with favorable clinical outcomes. The PVTT response to TACE-RT reduces metastasis and makes it possible to maintain normal liver function and achieve longer survival.

Clinical outcomes of stereotactic body radiotherapy for spinal metastases from hepatocellular carcinoma

Purpose To investigate the outcomes of patients with spinal metastases from hepatocellular carcinoma (HCC), who were treated by stereotactic body radiotherapy (SBRT). Materials and Methods This retrospective study evaluated 23 patients who underwent SBRT from October 2008 to August 2012 for 36 spinal metastases from HCC. SBRT consisted of approximately 2 fractionation schedules, which were 18 to 40 Gy in 1 to 4 fractions for group A lesions (n = 15) and 50 Gy in 10 fractions for group B lesions (n = 21). Results The median follow-up period was 7 months (range, 2 to 16 months). Seven patients developed grade 1 or 2 gastrointestinal toxicity, and one developed grade 2 leucopenia. Compression fractures occurred in association with 25% of the lesions, with a median time to fracture of 2 months. Pain relief occurred in 92.3% and 68.4% of group A and B lesions, respectively. Radiologic response (complete and partial response) occurred in 80.0% and 61.9% of group A and B lesions, respectively. The estimated 1-year spinal-tumor progression-free survival rate was 78.5%. The median overall survival period and 1-year overall survival rate were 9 months (range, 2 to 16 months) and 25.7%, respectively. Conclusion SBRT for spinal metastases from HCC is well tolerated and effective at providing pain relief and radiologic response. Because compression fractures develop at a high rate following SBRT for spinal metastases from primary HCC, careful follow up of the patient is required.

High Dose Involved Field Radiation Therapy as Salvage for Loco-Regional Recurrence of Non-Small Cell Lung Cancer

Purpose To determine the effectiveness of salvage radiation therapy (RT) in patients with loco-regional recurrences (LRR) following initial complete resection of non-small cell lung cancer (NSCLC) and assess prognostic factors affecting survivals. Materials and Methods Between 1994 and 2007, 64 patients with LRR after surgery of NSCLC were treated with high dose RT alone (78.1%) or concurrent chemo-radiation therapy (CCRT, 21.9%) at Samsung Medical Center. Twenty-nine patients (45.3%) had local recurrence, 26 patients (40.6%) had regional recurrence and 9 patients (14.1%) had recurrence of both components. The median RT dose was 54 Gy (range, 44-66 Gy). The radiation target volume included the recurrent lesions only. Results The median follow-up time from the start of RT in survivors was 32.0 months. The rates of in-field failure free survival, intra-thoracic failure free survival and extra-thoracic failure free survival at 2 years were 52.3%, 33.9% and 59.4%, respectively. The median survival after RT was 18.5 months, and 2-year overall survival (OS) rate was 47.9%. On both univariate and multivariate analysis, the interval from surgery till recurrence and CCRT were significant prognostic factors for OS. Conclusion The current study demonstrates that involved field salvage RT is effective for LRR of NSCLC following surgery.

Treatment outcome of hepatic re-irradiation in patients with hepatocellular carcinoma.

Purpose We evaluated the efficacy and toxicity of repeated high dose 3-dimensional conformal radiation therapy (3D-CRT) for patients with unresectable hepatocellular carcinoma. Materials and Methods Between 1998 and 2011, 45 patients received hepatic re-irradiation with high dose 3D-CRT in Samsung Medical Center. After excluding two ineligible patients, 43 patients were retrospectively reviewed. RT was delivered with palliative or salvage intent, and equivalent dose of 2 Gy fractions for α/β = 10 Gy ranged from 31.25 Gy10 to 93.75 Gy10 (median, 44 Gy10). Tumor response and toxicity were evaluated based on the modified Response Evaluation Criteria in Solid Tumors criteria and the Common Terminology Criteria for Adverse Events (CTCAE) ver. 4.0. Results The median follow-up duration was 11.2 months (range, 4.1 to 58.3 months). An objective tumor response rate was 62.8%. The tumor response rates were 81.0% and 45.5% in patients receiving ≥45 Gy10 and <45 Gy10, respectively (p = 0.016). The median overall survival (OS) of all patients was 11.2 months. The OS was significantly affected by the Child-Pugh class as 14.2 months vs. 6.1 months (Child-Pugh A vs. B, p < 0.001), and modified Union for International Cancer Control (UICC) T stage as 15.6 months vs. 8.3 months (T1-3 vs. T4, p = 0.004), respectively. Grade III toxicities were developed in two patients, both of whom received ≥50 Gy10. Conclusion Hepatic re-irradiation may be an effective and tolerable treatment for patients who are not eligible for further local treatment modalities, especially in patients with Child-Pugh A and T1-3.

High Dose Three-Dimensional Conformal Boost Using the Real-Time Tumor Tracking Radiotherapy System in Cervical Cancer Patients Unable to Receive Intracavitary Brachytherapy

Purpose The purpose of this study is to evaluate the clinical results of treatment with a high dose of 3-dimensional conformal boost (3DCB) using a real-time tracking radiation therapy (RTRT) system in cervical cancer patients. Materials and Methods Between January 2001 and December 2004, 10 patients with cervical cancer were treated with a high dose 3DCB using RTRT system. Nine patients received whole pelvis radiation therapy (RT) with a median dose of 50 Gy (range, 40-50 Gy) before the 3DCB. The median dose of the 3DCB was 30 Gy (range, 25-30 Gy). Eight patients received the 3DCB twice a week with a daily fraction of 5 Gy. The determined endpoints were tumor response, overall survival, local failure free survival, and distant metastasis free survival. The duration of survival was calculated from the time of the start of radiotherapy. Results All patients were alive at the time of analysis and the median follow-up was 17.6 months (range, 4.9-27.3 months). Complete response was achieved in nine patients and one patient had a partial response. The 1- and 2-year local failure free survival was 78.8% and 54%, respectively. The 1- and 2-year distant metastasis free survival was 90% and 72%, respectively. Late toxicity of a grade 2 rectal hemorrhage was seen in one patient. A subcutaneous abscess was encountered in one patient. Conclusion The use of the high dose 3DCB in the treatment of cervical cancer is safe and feasible where intracavitary brachytherapy (ICBT) is unable to be performed. The escalation of the 3DCB dose is currently under evaluation.

Radiotherapy for Adrenal Metastasis from Hepatocellular Carcinoma: A Multi-Institutional Retrospective Study (KROG 13-05)

Although the adrenal glands are not common sites of metastasis from hepatocellular carcinoma (HCC), this metastasis can be met in patients with advanced HCC in some clinical settings. However, the effectiveness of radiotherapy against such metastases is unclear. Therefore, we performed the present multi-institutional study to investigate tumor response, overall survival (OS), treatment-related toxicity, and prognostic factors after radiotherapy. We retrospectively reviewed 134 patients who completed a planned radiotherapy for their adrenal metastases. Complete response was noted in 6 (4.3%), partial response in 48 (34.0%), and stable disease in 78 patients (55.3%). The median OS was 12.8 months, and the 1-, 2-, and 5-year OS rates were 53.1%, 23.9%, and 9.3%, respectively. Grade 3 anorexia occurred in 2 patients, grade 3 diarrhea in 1, and grade 3 fatigue in 1. Multivariate analyses revealed that the following factors had significant effects on OS: controlled intrahepatic tumor; controlled extrahepatic metastasis; and Child-Pugh class A. Although patients with adrenal metastasis from HCC had poor OS, radiotherapy provided an objective response rate of 38.3% and disease stability of 93.6%, with minimal adverse events. Therefore, radiotherapy for these patients could represent a good treatment modality, especially for patients with controlled intrahepatic tumors, controlled extrahepatic metastasis, and good hepatic function.

Variation in Practice Patterns of Korean Radiation Oncologists for Spine Metastasis between 2009 and 2014

Purpose The Korean Society of Radiation Oncologists (KOSRO) conducted the Patterns of Care Study (PCS) of radiotherapy (RT) for spine metastases in 2009. The current study was conducted to investigate current practice patterns and compare them with the results of the PCS. Materials and Methods The survey questionnaire was composed of 10 questions regarding general information and seven questions for each of two clinical scenarios. Results Fifty-four members of the KOSRO answered at least one question on the web-based questionnaire. The yearly number of patients treated who underwent palliative spine RT was greater than 200 in 14 (25.9%), 51 to 100 in 13 (24.1%), and 31 to 50 in 11 respondents (20.4%). Scenario 1 described a patient presenting with cord compressive spine metastasis in multiple bones and liver metastasis from non-small cell lung cancer. Thirty gray (Gy) in 10 fractions was chosen by 35 respondents (64.8%). Scenario 2 described a case of a single spine metastasis without progression after targeted therapy. Thirty Gy in 10 fractions was chosen by 19 respondents (35.2%), and a single fraction or less than four fractions of stereotactic ablative radiotherapy (SABR) were selected by 18 respondents (33.3%). When compared with the 2009 PCS, practice patterns of Korean radiation oncologists had not changed significantly over 5 years, except that SABR emerged as a new treatment modality in the selected population. Conclusion The 2014 PCS demonstrated that multiple fraction RT is still preferred in a considerable proportion of Korean radiation oncologists.