Distinct Repopulation Activity in Hu-Mice between CBand LPB-CD34＋ Cells by Enrichment of Transcription Factors

Background and Objectives@#Human CD34＋hematopoietic stem cells can reconstitute the human hematopoietic system when transplanted into immunocompromised mice after irradiation. Human leukapheresis peripheral blood (LPB)-and cord blood (CB)-derived CD34＋ cells have a similar capacity to reconstitute myeloid lineage cells in a humanized mice (hu-mice) model. However, potent stem cells, such as CB-CD34＋ cells, efficiently reconstitute the lymphoid system in vivo compared to LPB-CD34 ＋ cells. Modeling the human hematolymphoid system is vital for studying immune cell crosstalk in human xenografted mice, with CB-CD34＋ cells used as an optimized cell source because they are essential in reconstituting lymphoid lineage cells. @*Methods@#and Results: In this study, we established hu-mice that combined human characteristics with long-term survival and investigated the efficiency of the engraftment of lymphoid lineage cells derived from LPB- and CB-CD34＋cells in the bone marrow, spleen, and LPB. We found an overall increase in the transcriptional activity of lymphoid lineage genes in CB-CD34＋ cells. Our results revealed that potent CB-CD34＋ cells displaying a general upregulation of the expression of genes involved in lymphopoiesis could contribute to the hematolymphoid system in the humanized mice model with longevity. @*Conclusions@#Our data suggest that humanized mouse model by usage of CB-CD34 ＋ cells displaying high expression of TFs for lymphoid lineage cells can contribute to study the immune response against lymphocytes.

Distinct Repopulation Activity in Hu-Mice between CBand LPB-CD34＋ Cells by Enrichment of Transcription Factors

Background and Objectives@#Human CD34＋hematopoietic stem cells can reconstitute the human hematopoietic system when transplanted into immunocompromised mice after irradiation. Human leukapheresis peripheral blood (LPB)-and cord blood (CB)-derived CD34＋ cells have a similar capacity to reconstitute myeloid lineage cells in a humanized mice (hu-mice) model. However, potent stem cells, such as CB-CD34＋ cells, efficiently reconstitute the lymphoid system in vivo compared to LPB-CD34 ＋ cells. Modeling the human hematolymphoid system is vital for studying immune cell crosstalk in human xenografted mice, with CB-CD34＋ cells used as an optimized cell source because they are essential in reconstituting lymphoid lineage cells. @*Methods@#and Results: In this study, we established hu-mice that combined human characteristics with long-term survival and investigated the efficiency of the engraftment of lymphoid lineage cells derived from LPB- and CB-CD34＋cells in the bone marrow, spleen, and LPB. We found an overall increase in the transcriptional activity of lymphoid lineage genes in CB-CD34＋ cells. Our results revealed that potent CB-CD34＋ cells displaying a general upregulation of the expression of genes involved in lymphopoiesis could contribute to the hematolymphoid system in the humanized mice model with longevity. @*Conclusions@#Our data suggest that humanized mouse model by usage of CB-CD34 ＋ cells displaying high expression of TFs for lymphoid lineage cells can contribute to study the immune response against lymphocytes.

Re-Irradiation and Its Contribution to Good Prognosisin Recurrent Glioblastoma Patients

Background@#: Radiation therapy, one of the strongest anti-cancer treatments, is already performed totreat primary glioblastoma; however, the effect of repeated radiation therapy for recurrent tumors has notbeen fully explored. The aim of this study was to determine the efficacy of re-irradiation in treating recurrentglioblastoma. @*Methods@#: The study included 36 patients with recurrent glioblastoma treated with repeated radiationtherapy between 2002 and 2016. Stereotactic radiosurgery (SRS) and hypo-fractionated stereotacticradiotherapy (HSRT) were performed in these patients. @*Results@#: Fourteen patients received SRS with a median dose of 25 Gy (range, 20-32 Gy) in1-5 fractions. Twenty-two patients received HSRT with a median dose of 40 Gy (range, 31.5-52 Gy) in6-20 fractions. There were six treatment-related grade 3 adverse events. Survival analysis showed thatre-irradiation significantly prolonged overall survival (OS) and progression-free survival (PFS). The medianOS and one-year OS rate after re-irradiation were 17.2 months and 60.4%, respectively. The medianPFS and 6-month PFS rate after re-irradiation were 4.4 months and 41.9%, respectively. Of the 36 patients,three survived without any progression in their condition. @*Conclusion@#: Re-irradiation for recurrent glioblastoma showed favorable outcomes. Radiation doseand fractionation should be carefully considered to minimize radiation necrosis.

Two Distinct Subsets Are Identified from the Peritoneal Myeloid Mononuclear Cells Expressing both CD11c and CD115

To this date, the criteria to distinguish peritoneal macrophages and dendritic cells (DCs) are not clear. Here we delineate the subsets of myeloid mononuclear cells in the mouse peritoneal cavity. Considering phenotypical, functional, and ontogenic features, peritoneal myeloid mononuclear cells are divided into 5 subsets: large peritoneal macrophages (LPMs), small peritoneal macrophages (SPMs), DCs, and 2 MHCII⁺CD11c⁺CD115⁺ subpopulations (i.e., MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ and MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺). Among them, 2 subsets of competent Ag presenting cells are demonstrated with distinct functional characteristics, one being DCs and the other being MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells. DCs are able to promote fully activated T cells and superior in expanding cytokine producing inflammatory T cells, whereas MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells generate partially activated T cells and possess a greater ability to induce Treg under TGF-β and retinoic acid conditions. While the development of DCs and MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells are responsive to the treatment of FLT3 ligand and GM-CSF, the number of LPMs, SPMs, and MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺ cells are only influenced by the injection of GM-CSF. In addition, the analysis of gene expression profiles among MHCII⁺ peritoneal myeloid mononuclear cells reveals that MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺ cells share high similarity with SPMs, whereas MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells are related to peritoneal DC2s. Collectively, our study identifies 2 distinct subpopulations of MHCII⁺CD11c⁺CD115⁺ cells, 1) MHCII⁺CD11c⁺CD115⁺CD14⁻CD206⁻ cells closely related to peritoneal DC2s and 2) MHCII⁺CD11c⁺CD115⁺CD14⁺CD206⁺ cells to SPMs.

Extended Culture of Bone Marrow with Granulocyte Macrophage-Colony Stimulating Factor Generates Immunosuppressive Cells

Bone marrow-derived dendritic cells (BM-DCs) are generated from bone marrow (BM) cells cultured with granulocyte macrophage-colony stimulating factor (GM-CSF) for a week. In this study we investigated the effect of duration on the BM culture with GM-CSF. Within several months, the cells in the BM culture gradually expressed homogeneous levels of CD11c and major histocompatibility complex II on surface, and they became unable to stimulate allogeneic naïve T cells in mixed lymphocyte reaction (MLR). In addition, when the BM culture were sustained for 32 wk or longer, the BM cells acquired ability to suppress the proliferation of allogeneic T cells in MLR as well as the response of ovalbumin-specific OT-I transgenic T cells in antigen-dependent manner. We found that, except for programmed death-ligand 1, most cell surface molecules were expressed lower in the BM cells cultured with GM-CSF for the extended duration. These results indicate that BM cells in the extended culture with GM-CSF undergo 2 distinct steps of functional change; first, they lose the immunostimulatory capacity; and next, they gain the immunosuppressive ability.

Incorporating Risk Factors to Identify the Indication of Post-mastectomy Radiotherapy in N1 Breast Cancer Treated with Optimal Systemic Therapy: A Multicenter Analysis in Korea (KROG 14-23) / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: In a recent meta-analysis, post-mastectomy radiotherapy (PMRT) reduced any first recurrence (AFR) and improved survival in N1 and N2 patients. We investigated risk factors for AFR in N1 after optimal systemic therapy without PMRT, to define a subgroup of patients who may benefit from PMRT. MATERIALS AND METHODS: One thousand three hundred eighty-two pT1-2N1M0 breast cancer patients treated with mastectomy without PMRT between 2005 and 2010 were retrospectively analyzed. Only 0.6% had no systemic therapy. RESULTS: After a median follow-up of 5.9 years, there were 173 AFR (53 loco-regional recurrence [LRR] without distant metastases [DM], 38 LRR with DM, and 82 DM without LRR). The 5-year LRR and AFR rates were 6.1% and 12.0%, respectively. Multivariate analysis revealed that close resection margin (p=0.001) was the only independent risk factor for LRR. Multivariate analysis for AFR revealed that age < 35 years (p=0.025), T2 stage (p=0.004), high tumor grade (p=0.032), close resection margin (p=0.035), and triple-negative biological subtype (p=0.031) were independent risk factors. Two or three positive lymph nodes (p=0.078) were considered a marginally significant factor. When stratified by these six factors, the 5-year LRR rates were 3.6% with 0-1 (n=606), 7.5% with 2-3 (n=655), and 12.7% with 4-6 (n=93) risk factors. The 5-year AFR rates were 7.1% with 0-1, 15.0% with 2-3, and 24.5% with 4-6 risk factors. CONCLUSION: Patients with pT1-2N1M0 breast cancer who underwent mastectomy and optimal systemic therapy showed excellent loco-regional control and disease control. The patients with four or more risk factors may benefit from PMRT, and those with two or three risk factors merit consideration of PMRT.

Incorporating Risk Factors to Identify the Indication of Post-mastectomy Radiotherapy in N1 Breast Cancer Treated with Optimal Systemic Therapy: A Multicenter Analysis in Korea (KROG 14-23) / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: In a recent meta-analysis, post-mastectomy radiotherapy (PMRT) reduced any first recurrence (AFR) and improved survival in N1 and N2 patients. We investigated risk factors for AFR in N1 after optimal systemic therapy without PMRT, to define a subgroup of patients who may benefit from PMRT. MATERIALS AND METHODS: One thousand three hundred eighty-two pT1-2N1M0 breast cancer patients treated with mastectomy without PMRT between 2005 and 2010 were retrospectively analyzed. Only 0.6% had no systemic therapy. RESULTS: After a median follow-up of 5.9 years, there were 173 AFR (53 loco-regional recurrence [LRR] without distant metastases [DM], 38 LRR with DM, and 82 DM without LRR). The 5-year LRR and AFR rates were 6.1% and 12.0%, respectively. Multivariate analysis revealed that close resection margin (p=0.001) was the only independent risk factor for LRR. Multivariate analysis for AFR revealed that age < 35 years (p=0.025), T2 stage (p=0.004), high tumor grade (p=0.032), close resection margin (p=0.035), and triple-negative biological subtype (p=0.031) were independent risk factors. Two or three positive lymph nodes (p=0.078) were considered a marginally significant factor. When stratified by these six factors, the 5-year LRR rates were 3.6% with 0-1 (n=606), 7.5% with 2-3 (n=655), and 12.7% with 4-6 (n=93) risk factors. The 5-year AFR rates were 7.1% with 0-1, 15.0% with 2-3, and 24.5% with 4-6 risk factors. CONCLUSION: Patients with pT1-2N1M0 breast cancer who underwent mastectomy and optimal systemic therapy showed excellent loco-regional control and disease control. The patients with four or more risk factors may benefit from PMRT, and those with two or three risk factors merit consideration of PMRT.

Radiation Pneumonitis in Association with Internal Mammary Node Irradiation in Breast Cancer Patients: An Ancillary Result from the KROG 08-06 Study / 한국유방암학회지

PURPOSE: The aim of this study is to present the incidence of radiation pneumonitis (RP) reported within 6 months after treatment for breast cancer with or without internal mammary node irradiation (IMNI). METHODS: In the Korean Radiation Oncology Group (KROG) 08-06 phase III randomized trial, patients who were node-positive after surgery were randomly assigned to receive radiotherapy either with or without IMNI. A total of 747 patients were enrolled, and three-dimensional treatment planning with computed tomography simulation was performed for all patients. Of the 747 patients, 722 underwent chest X-rays before and within 6 months after radiotherapy. These 722 patients underwent evaluation, and RP was diagnosed on the basis of chest radiography findings and clinical symptoms. The relationship between the incidence of RP and clinical/dosimetric parameters was analyzed. RESULTS: RP developed in 35 patients (4.8%), including grade 1 RP in 26 patients (3.6%), grade 2 RP in nine patients (1.2%); there was no incidence of grade 3 or higher RP. Grade 2 RP cases were observed in only the IMNI group. The risk of developing RP was influenced by IMNI treatment; pneumonitis occurred in 6.5% of patients (n=23/356) who underwent IMNI and in 3.3% of patients (n=12/366) who did not (p=0.047). The differences in lung dosimetric parameters (mean lung dose, V10–40) were statistically significant between the two groups. CONCLUSION: IMNI treatment resulted in increased radiation exposure to the lung and a higher rate of RP, but the incidence and severity of RP was minimal and acceptable. This minor impact on morbidity should be balanced with the impact on survival outcome in future analyses.

Effect of aldosterone on epithelial-to-mesenchymal transition of human peritoneal mesothelial cells

BACKGROUND: Peritoneal fibrosis is one of the major causes of technical failure in patients on peritoneal dialysis. Epithelial-to-mesenchymal transition (EMT) of the peritoneum is an early and reversible mechanism of peritoneal fibrosis. Human peritoneal mesothelial cells (HPMCs) have their own renin-angiotensin-aldosterone system (RAAS), however, it has not been investigated whether aldosterone, an end-product of the RAAS, induces EMT in HPMCs, and which mechanisms are responsible for aldosterone-induced EMT. METHODS: EMT of HPMCs was evaluated by comparing the expression of epithelial cell marker, E-cadherin, and mesenchymal cell marker, alpha-smooth muscle actin after stimulation with aldosterone (1-100nM) or spironolactone. Activation of extracellular signal-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) and generation of reactive oxygen species (ROS) were assessed by western blotting and 2',7'-dichlorofluororescein diacetate staining, respectively. The effects of MAPK inhibitors or antioxidants (N-acetyl cysteine, apocynin, and rotenone) on aldosterone-induced EMT were evaluated. RESULTS: Aldosterone induced EMT in cultured HPMCs, and spironolactone blocked aldosterone-induced EMT. Aldosterone induced activation of both ERK1/2 and p38 MAPK from 1 hour. Either PD98059, an inhibitor of ERK1/2, or SB20358, an inhibitor of p38 MAPK, attenuated aldosterone-induced EMT. Aldosterone induced ROS in HPMCs from 5 minutes, and antioxidant treatment ameliorated aldosterone-induced EMT. N-acetyl cysteine and apocynin alleviated activation of ERK and p38 MAPK. CONCLUSION: Aldosterone induced EMT in HPMCs by acting through the mineralocorticoid receptor. Aldosterone-induced generation of ROS followed by activation of ERK, and p38 MAPK served as one of the mechanisms of aldosterone-induced EMT of HPMCs.

Difference in the rate of rectal complications following prostate brachytherapy based on the prostate-rectum distance and the prostate longitudinal length among early prostate cancer patients

PURPOSE: To investigate the difference in rectal complications rate following prostate low dose rate (LDR) brachytherapy based on prostate-rectum distance and prostate longitudinal length among early prostate cancer patients. MATERIALS AND METHODS: From March 2008 to February 2013, 245 prostate cancer patients with a Gleason score or =6 months were evaluated for radiation proctitis. Magnetic resonance imaging (MRI) was performed for a prebrachytherapy evaluation, and prostate-rectum distance and prostate longitudinal length were measured. The radiation proctitis was confirmed and graded via colonoscopy based on the radiation therapy oncology group (RTOG) toxicity criteria. RESULTS: Twenty-three patients received a colonoscopy for proctitis evaluation, and 12 were identified as grade 1 on the RTOG scale. Nine patients were diagnosed as grade 2 and 2 patients were grade 3. No patient developed grade 4 proctitis. The rectal-complication group had a mean prostate-rectum distance of 2.51+/-0.16 mm, while non-rectal-complication control group had 3.32+/-0.31 mm. The grade 1 proctitis patients had a mean prostate-rectum distance of 2.80+/-0.15 mm, which was significantly longer than 2.12+/-0.31 mm of grades 2 and 3 patient groups (p=0.045). All 11 patients of grades 2 and 3 had a prostate longitudinal length of 35.22+/-2.50 mm, which was longer than group 1, but the difference was not statistically significant (p=0.214). CONCLUSIONS: As the prostate-rectum distance increased, fewer postimplantation rectal symptoms were observed. Patients with a shorter prostate-rectum distance in MRI should receive modified implantation techniques or radical prostatectomy.

Risk Factors for Distant Metastasis as a Primary Site of Treatment Failure in Early-Stage Breast Cancer / 전남의대학술지

The aim of this study was to evaluate the risk factors for distant metastasis (DM) as a primary site of failure in early-stage breast cancer. Data from 294 patients diagnosed with pathologic stage I or II breast cancer between January 2000 and December 2005 were reviewed retrospectively. Median follow-up duration was 81.0 months (range, 18-135 months). The total number of patients with DM without evidence of locoregional recurrence was 20 and the median time between surgery and DM was 29 months (range, 9-79 months). Median survival time was 38 months (range, 22-77 months) after operation. HER-2 positivity (p=0.015), T stage of tumor (p=0.012), and number of involved lymph nodes (p=0.008) were significant predictors of DM in the univariable analysis. Number of involved lymph nodes [p=0.005, hazards ratio (HR): 1.741; 95% confidence interval (CI): 1.178-2.574] and HER-2 positivity (p=0.018, HR: 2.888; 95% CI: 1.201-6.941) had a statistically significant effect on DM-free survival in the multivariable analysis. A cautious evaluation may be helpful when patients with risk factors for DM have symptoms implying the possibility of DM. To reduce DM, applying intensive therapy is needed after curative surgery for patients with high risk for DM.

Risk Factors for Distant Metastasis as a Primary Site of Treatment Failure in Early-Stage Breast Cancer / 전남의대학술지

The aim of this study was to evaluate the risk factors for distant metastasis (DM) as a primary site of failure in early-stage breast cancer. Data from 294 patients diagnosed with pathologic stage I or II breast cancer between January 2000 and December 2005 were reviewed retrospectively. Median follow-up duration was 81.0 months (range, 18-135 months). The total number of patients with DM without evidence of locoregional recurrence was 20 and the median time between surgery and DM was 29 months (range, 9-79 months). Median survival time was 38 months (range, 22-77 months) after operation. HER-2 positivity (p=0.015), T stage of tumor (p=0.012), and number of involved lymph nodes (p=0.008) were significant predictors of DM in the univariable analysis. Number of involved lymph nodes [p=0.005, hazards ratio (HR): 1.741; 95% confidence interval (CI): 1.178-2.574] and HER-2 positivity (p=0.018, HR: 2.888; 95% CI: 1.201-6.941) had a statistically significant effect on DM-free survival in the multivariable analysis. A cautious evaluation may be helpful when patients with risk factors for DM have symptoms implying the possibility of DM. To reduce DM, applying intensive therapy is needed after curative surgery for patients with high risk for DM.

Esophageal tolerance to high-dose stereotactic radiosurgery

PURPOSE: Esophageal tolerance is needed to guide the safe administration of stereotactic radiosurgery (SRS). We evaluated comprehensive dose-volume parameters of acute esophageal toxicity in patients with spinal metastasis treated with SRS. MATERIALS AND METHODS: From May 2008 to May 2011, 30 cases in 27 patients with spinal metastasis received single fraction SRS to targets neighboring esophagus. Endpoints evaluated include length (mm), volume (mL), maximal dose (Gy), and series of dose-volume thresholds from the dose-volume histogram (volume of the organ treated beyond a threshold dose). RESULTS: The median time from the start of irradiation to development of esophageal toxicity was 2 weeks (range, 1 to 12 weeks). Six events of grade 1 esophageal toxicity occurred. No grade 2 or higher events were observed. V15 of external surface of esophagus was found to predict acute esophageal toxicity revealed by multivariate analysis (odds radio = 1.272, p = 0.047). CONCLUSION: In patients with spinal metastasis who received SRS for palliation of symptoms, the threshold dose-volume parameter associated with acute esophageal toxicity was found to be V15 of external surface of esophagus. Restrict V15 to external surface of esophagus as low as possible might be safe and feasible in radiosurgery.

Outcomes of Gleason Score < or =8 among High Risk Prostate Cancer Treated with 125I Low Dose Rate Brachytherapy Based Multimodal Therapy

PURPOSE: To investigate the role of low dose rate (LDR) brachytherapy-based multimodal therapy in high-risk prostate cancer (PCa) and analyze its optimal indications. MATERIALS AND METHODS: We reviewed the records of 50 high-risk PCa patients [clinical stage > or =T2c, prostate-specific antigen (PSA) >20 ng/mL, or biopsy Gleason score > or =8] who had undergone 125I LDR brachytherapy since April 2007. We excluded those with a follow-up period or =9 and Gleason score or =9 (p or =9 was observed to be significantly associated with BCR (p=0.021). Acute and late grade > or =3 toxicities were observed in 20% (10/50) and 36% (18/50) patients, respectively. CONCLUSION: Our results showed that 125I LDR brachytherapy-based multimodal therapy in high-risk PCa produced encouraging relatively long-term results among the Asian population, especially in patients with Gleason score or =9 was a significant predictor of BCR among high risk PCa patients after brachytherapy.

Treatment outcome in patients with triple negative early stage breast cancers compared with other molecular subtypes

PURPOSE: To determine whether triple negative (TN) early stage breast cancers have poorer survival rates compared with other molecular types. MATERIALS AND METHODS: Between August 2000 and July 2006, patients diagnosed with stage I, II early stage breast cancers, in whom all three markers (estrogen receptor, progesterone receptor, and human epidermal growth factor receptor [HER]-2) were available and treated with modified radical mastectomy or breast conserving surgery followed by radiotherapy, were retrospectively reviewed. RESULTS: Of 446 patients, 94 (21.1%) were classified as TN, 57 (12.8%) as HER-2 type, and 295 (66.1%) as luminal. TN was more frequently associated with young patients younger than 35 years old (p = 0.002), higher histologic grade (p 0.05). CONCLUSION: We found that patients with TN early stage breast cancers had no difference in survival rates compared with other molecular subtypes. Prospective study in homogeneous treatment group will need for a prognosis of TN early stage breast cancer.

A comparison of preplan MRI and preplan CT-based prostate volume with intraoperative ultrasound-based prostate volume in real-time permanent brachytherapy

PURPOSE: The present study compared the difference between intraoperative transrectal ultrasound (iTRUS)-based prostate volume and preplan computed tomography (CT), preplan magnetic resonance imaging (MRI)-based prostate volume to estimate the number of seeds needed for appropriate dose coverage in permanent brachytherapy for prostate cancer. MATERIALS AND METHODS: Between March 2007 and March 2011, among 112 patients who underwent permanent brachytherapy with 125I, 60 image scans of 56 patients who underwent preplan CT (pCT) or preplan MRI (pMRI) within 2 months before brachytherapy were retrospectively reviewed. Twenty-four cases among 30 cases with pCT and 26 cases among 30 cases with pMRI received neoadjuvant hormone therapy (NHT). In 34 cases, NHT started after acquisition of preplan image. The median duration of NHT after preplan image acquisition was 17 and 21 days for cases with pCT and pMRI, respectively. The prostate volume calculated by different modalities was compared. And retrospective planning with iTRUS image was performed to estimate the number of 125I seed required to obtain recommended dose distribution according to prostate volume. RESULTS: The mean difference in prostate volume was 9.05 mL between the pCT and iTRUS and 6.84 mL between the pMRI and iTRUS. The prostate volume was roughly overestimated by 1.36 times with pCT and by 1.33 times with pMRI. For 34 cases which received NHT after image acquisition, the prostate volume was roughly overestimated by 1.45 times with pCT and by 1.37 times with pMRI. A statistically significant difference was found between preplan image-based volume and iTRUS-based volume (p < 0.001). The median number of wasted seeds is approximately 13, when the pCT or pMRI volume was accepted without modification to assess the required number of seeds for brachytherapy. CONCLUSION: pCT-based volume and pMRI-based volume tended to overestimate prostate volume in comparison to iTRUS-based volume. To reduce wasted seeds and cost of the brachytherapy, we should take the volume discrepancy into account when we estimate the number of 125I seeds for permanent brachytherapy.

A Correction Method of Dose to Attenuation Rate of Transmitting Photon Beam Through Couch Top for Radiosurgery Using Novalis / 의학물리

This study has its own goal to deliver the accurate dose on the target volume by calculating and modifying the attenuation rate of photon beam transmitting the couch top with geometric model. The experiment was that the transmission rate and attenuation rate of photon beam transmitting the couch top was predicted by the geometric model, then compared and analyzed with what was measured experimentally based on that. The result showed that the predicted value by the geometric model accorded closely with the experimental value. In addition, in order to judge whether the practical clinical application is available, the point dose, measured after modifying the attenuation rate modelinged according to the treatment plan of a patient of spine radiosurgery, was compared with the one done nothing. The result was that the former showed decreased error range with treatment planned one than the latter. This papers calculated the transmission and attenuation rate with the geometric model transmitting the couch top and verified it experimentally. This method is expected to be very useful in not only the radiosurgery using Novalis but also the general radiation therapy.

Permanent Brachytherapy of Localized Prostate Cancer: Preliminary Results / 대한방사선종양학회지

PURPOSE: To evaluate the biochemical control rate and the rate of side effects after performing permanent brachytherapy of localized prostate cancer. MATERIALS AND METHODS: 67 patients with localized prostate cancer were treated with brachytherapy between April 2007 and December 2008. Of these, 43 patients who were followed up and did not receive external radiotherapy were evaluated for the change in prostate specific antigen (PSA) level and the occurrence of side effects. In total, 18 patients were classified as low risk, 19 patients as intermediate risk, and 6 patients as high risk. The prescription dose was 145 Gy. RESULTS: A PSA increase greater than 2 ng/mL occurred in 2 patients (4.7%). Radiation Therapy Oncology Group (RTOG) grade 1 and 2 acute urologic complications (UC) occurred in 40 and 3 patients, respectively. Further, 5 patients had RTOG grade 1 acute rectal complication (RC). The numbers of RTOG grade 1, 2, and 3 chronic UC were 1, 4, and 1, respectively. The numbers of RTOG grade 1, 2, and 4 chronic RC were 5, 10, and 3, respectively. The statistically significant risk factors (RF) of acute RC were the minimal dose in the most irradiated 0.1 cc volume (D0.1CC, p=0.041) and absolute volume receiving 150% of the prescribed dose (V150cc, p=0.038) in the entire rectum (ER). The percentage (V100%, p=0.019) and absolute volume (V100cc, p=0.047) in the involved rectum (IR) were also statistically significant. The RF of chronic RC were V100% (p=0.011) in the ER and the D0.1cc (p=0.049), V100cc (p=0.023) in the IR. The number of used seeds were related with acute UC (p=0.028). CONCLUSION: Permanent brachytherpy of localized prostate cancer showed a favorable short term biochemical control rate. As such, selective intermediate and high risk patients can be managed with permanent brachytherapy. The effort to reduce rectal complication is also necessary.

Property of Dose Distribution in Accordance with Dose Rate Variation in Intensity Modulated Radiation Therapy / 의학물리

As radiation is irradiated from various directions in intensity modulated radiation therapy (IMRT), longer treatment time than conventional treatment method is taken. In case of the patients who have problem to keep same posture for long time because of pain and injury, reducing treatment time through increased dose rate is a way for effective treatment. This study measured and found out the variation of dose and dose distribution in accordance with dose rate variation. IMRT treatment plan was set up to investigate from 5 directions - 0degrees, 72degrees, 144degrees, 216degrees, 288degrees - using ECLIPSE system (Varian, SomaVision 6.5, USA). To confirm dose and dose rate in accordance with dose rate variation, dose rate was set up as 100, 300, 500 MU/min, and dose and dose distribution were measured using ionization chamber (PTW, TN31014) and film dosimeter (EDR2, Kodak). At this time, film dosimeter was inserted into acrylic phantom, then installed to run parallel with beam's irradiating direction, 21EX-S (Varian, USA) was utilized as linear accelerator for irradiation. The measured film dosimeter was analyzed using VXR-16 (Vidar System Corporation) to confirm dose distribution.

Low-Dose-Rate Brachytherapy for Low- and Intermediate-Risk Groups of Localized Prostate Cancer

PURPOSE: We applied low-dose-rate brachytherapy for low- and intermediate-risk groups of prostate cancer patients. Our initial experiences were analyzed to assess the result of low-dose-rate brachytherapy for low- and intermediate-risk groups of patients with localized prostate cancer. MATERIALS AND METHODS: A total of 50 consecutive patients have been treated with brachytherapy for 1 year since April 2007. Among them, a total of 24 patients in the low- or intermediate-risk groups were enrolled: 10 of the 24 patients were in the low-risk group (clinical T1a-T2b, Gleason score [GS] of 2-6, PSA<10 ng/ml), and 14 patients were in the intermediate-risk group (clinical T2b-T2c, Gleason score of 7, or PSA 10-20 ng/ml). Implantations were performed by practicing a real-time ultrasound-guided placement including prostatic capsular placement in the intermediate-risk group. All 24 patients were treated with 1 to 3 months of androgen-deprivation therapy. RESULTS: In the low- and intermediate-risk groups, the median patients' ages were 64 and 70 years, respectively. The numbers of patients in the low-risk group according to clinical T stage were 4 cases of T1c and 6 cases of T2a. The intermediate-risk group included 4 patients of stage T2a, 3 patients of stage T2b, and 7 patients of T2c. Five patients with a GS< or =6 and 9 patients with a GS of 7 were classified as being in the intermediate-risk group. Serum PSA levels in the intermediate-risk group were less than 10 ng/ml in 11 patients and 10-20 ng/ml in 3 patients. The median radiation doses delivered to 90% of the prostate in the low-risk and intermediate-risk groups were 257.5 Gy (range, 142.5-357.5 Gy) and 260.0 Gy (range, 147.5-357.5 Gy), respectively. Biochemical failure was not revealed in any case during follow-up. No patients experienced major complications. CONCLUSIONS: We can expect outstanding local control effect with low-dose-rate brachytherapy in low- and intermediate-risk prostate cancer. Our technique of modifying the insertion field in the intermediate-risk group is feasible and tolerable. However, long-term follow-up data are needed for this strategy.