Optimal follow-up duration for evaluating objective response to radiotherapy in patients with hepatocellular carcinoma: a retrospective study / 癌症

The time to complete or partial (objective) response to radiotherapy in patients with hepatocellular carcinoma (HCC) is variable; thus, the reported frequency of these responses depends on the length of follow-up. However, the optimum follow-up duration is unknown. We sought to determine the optimal follow-up duration by analyzing the medical records of 25 patients with 39 HCC lesions who received definitive helical tomotherapy at a daily dose of 2 to 4 Gy at 5 fractions per week, for a total dose of 40 to 60 Gy, between January 2008 and January 2013. We determined the time to objective treatment response and local recurrence after radiotherapy and assessed several predictors of delayed treatment response. The median follow-up duration was 15.2 months (range, 7.8 to 52.1 months). Among all 39 lesions, objective responses were observed for 36 (92.3%). The median time to objective response was 3.9 months (range, 1.5 to 9.8 months). The objective response rates increased over time from 15.4% at 3 months to 71.8% at 6 months and 87.2% at 9 months. Age 60 years old or older and post-radiotherapy α-fetoprotein concentrations higher than pre-radiotherapy concentrations predicted delayed treatment response. The objective response rate continued to increase over 9 months. Therefore, to fully evaluate the treatment response of HCC, we recommend continuous observation for at least 9 months after radiotherapy.

Tumor Regression Patterns Based on Follow-up Duration in Patients With Head and Neck Squamous Cell Carcinoma Treated With Radiotherapy or Chemoradiotherapy

OBJECTIVES: We describe patterns of tumor regression based on follow-up duration after radiotherapy (RT) or chemo-RT in patients with head and neck squamous cell carcinoma. METHODS: Thirty-one patients with head and neck squamous cell carcinoma were included in this study and received definitive RT or chemo-RT. The pattern of primary tumor regression after treatment was evaluated every 1 to 2 months. Predictive factors for the length of time to full regression were also analyzed. RESULTS: Among all patients, 27 patients showed regression of the primary tumor, 24 patients showed >50% regression, and 15 patients showed total regression. The primary tumor gradually regressed during the course of follow-up. The median time to full regression was 5.2 months (range, 1.3 to 17.9 months). In the 24 patients who showed >50% regression, the rate of >50% regression increased over time as follows: 25.0% at 1 month, 62.5% at 2 months, 75.0% at 3 months, 91.7% at 4 months, and 95.8% at 5 months. Higher total RT dose and shorter RT duration were associated with longer time to full regression. CONCLUSION: A substantial number of patients showed continuous regression of the primary tumor for more than 2 months after treatment. The timing for evaluation of tumor regression must be greater than 2 months from the completion of RT or chemo-RT in patients with head and neck squamous cell carcinoma.

Comparison of survival rates between patients treated with conventional radiotherapy and helical tomotherapy for head and neck cancer

PURPOSE: Compared to conventional radiotherapy (RT), intensity-modulated radiotherapy (IMRT) significantly reduces the rate of treatment-induced late toxicities in head and neck cancer. However, a clear survival benefit of IMRT over conventional RT has not yet been shown. This study is among the first comparative study to compare the survival rates between conventional RT and helical tomotherapy in head and neck cancer. MATERIALS AND METHODS: From January 2008 to November 2011, 37 patients received conventional RT and 30 patients received helical tomotherapy for management of head and neck cancer. We retrospectively compared the survival rates between patients treated with conventional RT and helical tomotherapy, and analyzed the prognostic factors for survival. RESULTS: The 1- and 2-year locoregional recurrence-free survival rates were 61.2% and 58.1% for the conventional RT group, 89.3% and 80.3% for the helical tomotherapy group, respectively. The locoregional recurrence-free survival rates of the helical tomotherapy group were significantly higher than conventional RT group (p = 0.029). There were no significant differences in the overall and distant metastasis-free survival between the two groups. RT technique, tumor stage, and RT duration were significant prognostic factors for locoregional recurrence-free survival. CONCLUSION: This study showed the locoregional recurrence-free survival benefits of helical tomotherapy in the treatment of head and neck cancers.

Predictive Factors for Radiation Pneumonitis in Lung Cancer Treated with Helical Tomotherapy / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Predictive factors for radiation pneumonitis (RP) after helical tomotherapy (HT) may differ from those after linac-based radiotherapy. In this study, we identified predictive factors for RP in patients with lung cancer treated with HT. MATERIALS AND METHODS: We retrospectively analyzed clinical, treatment-related and dosimetric factors from 31 patients with lung cancer treated with HT. RP was graded according to Common Terminology Criteria for Adverse Events version 4.0 and grade > or =2 RP was defined as a RP event. We used Kaplan-Meier methods to compute the actuarial incidence of RP. For univariate and multivariate analysis, the log-rank test and the Cox proportional regression hazard model were used. We generated receiver-operating characteristics (ROC) curves to define the cutoff values for significant parameters. RESULTS: The median follow-up duration was 6.6 months (range, 1.6 to 38.5 months). The 2-, 4-, and 6-month actuarial RP event rates were 13.2%, 58.5%, and 67.0%, respectively. There was no grade 4 or more RP. Ipsilateral V5, V10, V15, and contralateral V5 were related with RP event on univariate analysis. By multivariate analysis, ipsilateral V10 was factor most strongly associated with RP event. On the ROC curve, the cutoff values of ipsilateral V5, V10, V15, and contralateral V5 were 67.5%, 58.5%, 50.0%, and 55.5%, respectively. CONCLUSION: In our study, ipsilateral V5, V10, V15, and contralateral V5 were significant predictive factors for RP after HT.

Which Patients Might Benefit from Postmastectomy Radiotherapy in Breast Cancer Patients with T1-2 Tumor and 1-3 Axillary Lymph Nodes Metastasis? / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study compared the clinical outcomes of T1-2N1 breast cancer patients with and without postmastectomy radiotherapy (PMRT). Risk factors for loco-regional recurrence (LRR) were identified in order to define a subgroup of patients who might benefit from PMRT. MATERIALS AND METHODS: Of 110 T1-2N1 breast cancer patients who underwent mastectomy from January 1994 through December 2009, 32 patients underwent PMRT and 78 patients did not. Treatment outcomes and risk factors for LRR were analyzed. RESULTS: The 5- and 10-year LRR rates were both 6.2% in the PMRT group, and 10.4% and 14.6% in the no-PMRT group (p=0.336). In addition, no significant differences in distant metastasis-free survival (DMFS) or overall survival (OS) were observed between patients receiving and not receiving PMRT. In multivariate analysis, factors associated with higher LRR rates included grade 3 disease, extracapsular extension (ECE), and triple negative subtype. Patients who had one or more risk factors for LRR were defined as a high-risk patient group. In the high-risk group, both 5- and 10-year LRR rates for patients who underwent PMRT was 18.2%, and LRR rates of 21.4% at five years and 36.6% at 10 years were observed for patients who did not undergo PMRT (p=0.069). CONCLUSION: PMRT in T1-2N1 breast cancer patients should be considered according to several prognostic factors in addition to T and N stage. Findings of our study indicated that PMRT did not improve LRR, DMFS, or OS in T1-2N1 breast cancer patients. However, in a subgroup of patients with grade 3 disease, ECE, or triple negative subtype, PMRT might be beneficial.

Treatment Outcomes of Helical Intensity-Modulated Radiotherapy for Unresectable Hepatocellular Carcinoma

BACKGROUND/AIMS: This study reports treatment outcomes after helical intensity-modulated radiotherapy (IMRT) in unresectable hepatocellular carcinoma (HCC) patients for whom transarterial chemoembolization (TACE) was considered ineffective or unsuitable. METHODS: From January 2008 to December 2011, 22 unresectable HCC patients received helical IMRT. A daily dose of 1.8 to 4 Gy was delivered at five fractions per week to deliver a total dose of 30 to 60 Gy. The most-prescribed dose fractionation was a total dose of 50 to 57.5 Gy, with a daily dose of 2.3 to 2.5 Gy. RESULTS: In the entire group, the objective response rate of the primary tumor was 72.7%. In the eight patients with portal vein thrombosis (PVT), the objective response rate of PVT was 50.0%. Median disease progression-free survival was 11.8 months, and the 1-year disease progression-free survival rate was 40.2%. The median overall survival was 14.4 months, and the 1- and 2-year overall survival rates were 86.4% and 69.1%, respectively. PVT and Child-Pugh classifications were significant prognostic factors for overall survival in multivariate analyses. CONCLUSIONS: Helical IMRT in patients with unresectable HCC resulted in high treatment response and survival rates. This study suggests helical IMRT is a practical treatment option for HCC patients in whom TACE is unsuitable or ineffective.

Preoperative Concurrent Chemoradiotherapy for Locally Advanced Rectal Cancer: Treatment Outcomes and Analysis of Prognostic Factors / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study was designed to investigate the long-term oncologic outcomes for locally advanced rectal cancer patients after treatment with preoperative concurrent chemoradiotherapy followed by total mesorectal excision, and to identify prognostic factors that affect survival and pathologic response. MATERIALS AND METHODS: From June 1996 to June 2009, 135 patients with locally advanced rectal cancer were treated with preoperative concurrent chemoradiotherapy followed by total mesorectal excision at Kyung Hee University Hospital. Patient data was retrospectively collected and analyzed in order to determine the treatment outcomes and identify prognostic factors for survival. RESULTS: The median follow-up time was 50 months (range, 4.5 to 157.8 months). After preoperative chemoradiotherapy, sphincter preservation surgery was accomplished in 67.4% of whole patients. A complete pathologic response was achieved in 16% of patients. The estimated 5- and 8-year overall survival, loco-regional recurrence-free survival, and distant metastasis-free survival rate for all patients was 82.7% and 75.7%, 76.8% and 71.9%, 67.9% and 63.3%, respectively. The estimated 5- and 8-year overall survival, loco-regional recurrence-free survival, and distant metastasis-free survival rate for pathologic complete responders was 100% and 100%, 100% and 88.9%, 95.5% and 95.5%, respectively. In the multivariate analysis, pathologic complete response was significantly associated with overall survival. The predictive factor for pathologic complete response was pretreatment clinical stage. CONCLUSION: Preoperative chemoradiotherapy for locally advanced rectal cancer resulted in a high rate of overall survival, sphincter preservation, down-staging, and pathologic complete response. The patients achieving pathologic complete response had very favorable outcomes. Pathologic complete response was a significant prognostic factor for overall survival and the significant predictive factor for a pathologic complete response was pretreatment clinical stage.

Three Cases of Radiation-Induced Hepatitis B Virus Reactivation after Hepatic Tomotherapy: Case Report / 대한방사선종양학회지

Radiation-induced liver disease (RILD) has been characterized as a veno-occlusive disease with anicteric elevation of alkaline phosphatase (ALP). However, some RILD patients present with elevated transaminase levels rather than with anicteric elevation of ALP, and these findings are common in the Asia-Pacific region where hepatitis B virus (HBV) infection is associated with 70~90% of hepatocelluar carcinoma (HCC) cases. In addition, the development of RILD is more common in patients with hepatitis B virus-related HCC. These findings indicate that susceptibility to RILD might be different in HBV carriers and non-carriers, and moreover, RILD in patients with HBV-related HCC might be associated with another unique pathogenesis such as HBV reactivation. However, HBV reactivation after hepatic irradiation has been reported in only a few studies. This study reports three cases of HBV reactivation after hepatic tomotherapy for management of HCC.

Analysis of Accuracy of Apparent Activity According to Calibration Method for High Dose Rate Brachytherapy Source / 의학물리

The aim of this study is to introduce the accuracy of Ir-192 source's apparent activity using the well-type chamber and the Farmer-type ionization chamber in the high dose rate brachytherapy. We measured the apparent activity of Ir-192 that each medical center in the country has and the apparent activity of calibration certificate provided by manufacturer is compared with that by our experimental measurement. The number of sources used for the activity comparison was 5. The accuracy of the measured activity was in the range of -2.8% to -1.0% and -2.1% to 0.2% for the Farmer-type chamber system (Jig) and for the well-type, respectively. The maximum difference was within 1.0% for comparison with two calibration's tool. Our results demonstrate that well-type chamber as wall as Farmer-type chamber is a appropriate system as the routine source calibration procedures in HDR brachytherapy. Whenever a new source is installed to use in clinics, by periods, a source calibration should be carried out.

Adaptive Responses Induced by Low Dose Radiation in Dentate Gyrus of Rats

The purpose of this study is to investigate the mechanism of alternative responses to low dose irradiation for neuronal cell proliferation in the dentate gyrus of rats. To determine the effect of a single exposure to radiation, rats were irradiated with a single dose of 0.1, 1, 10 or 20 Gy. To determine the effect of the cumulative dose, the animals were irradiated daily with 0.01 Gy or 0.1 Gy from 1 to 4 days. The neuronal cell proliferation was evaluated using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), Ki-67 and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Four consecutive daily irradiations with a 0.01 Gy/fraction increased the number of BrdU-positive and Ki-67-positive cells in a dose dependent manner, but this did not affect the number of TUNEL-positive cells. However, there was not a dose dependent relationship for the 0.1 Gy/fraction irradiation with the number of BrdU, Ki-67 and TUNEL positive cells. Our data support the explanation that the adaptive response, induced by low-dose radiation, in the hippocampus of rats is more likely a reflection of the perturbations of cell cycle progression.

Low Dose Radiation Overcomes Diabetes-induced Suppression of Hippocampal Neuronal Cell Proliferation in Rats

We investigated the effect of low dose radiation on diabetes induced suppression of neurogenesis in the hippocampal dentate gyrus of rat. After 0.01 Gy, 0.1 Gy, 1 Gy and 10 Gy radiation was delivered, the dentate gyrus of hippocampus of streptozotocin (STZ)-induced diabetic rats were evaluated using immunohistochemistry for 5-bromo-2-deoxyuridine (BrdU), caspase-3, and terminal deoxynucleotidyl transferase-mediated nick end-labeling (TUNEL) staining. The number of BrdU positive cells in the non-diabetic rats, diabetic rats without radiation, diabetic rats with 0.01 Gy radiation, diabetic rats with 0.1 Gy radiation, diabetic rats with 1 Gy radiation and diabetic rats with 10 Gy radiation were 55.4+/-8.5/mm2, 33.3+/-6.4/mm2, 67.7+/-10.5/mm2, 66.6+/-10.0/mm2, 23.5+/-6.3/mm2 and 14.3+/-7.2/mm2, respectively. The number of caspase-3 positive cells was 132.6+/-37.4/mm2, 378.6+/-99.1/mm2, 15.0+/-2.8/mm2, 57.1+/-16.9/mm2, 191.8+/-44.8/mm2 and 450.4+/-58.3/mm2, respectively. The number of TUNEL-positive cells was 24.5+/-2.0/mm2, 21.7+/-4.0/mm2, 20.4+/-2.0/mm2, 18.96+/-2.1/mm2, 58.3+/-7.9/mm2, and 106.0+/-9.8/mm2, respectively. These results suggest low doses of radiation paradoxically improved diabetes induced neuronal cell suppression in the hippocampal dentate gyrus of rat.

Development of Web-based Dosimetry Calibration Program for High Energy Radiation / 의학물리

Absorbed dose dosimetry protocols of high energy photon and electron beams, which are widely used and based on an air kerma calibration factors, have somewhat complex formalism and limitations for improving dosimetric accuracy due to uncertainty of the physical parameters used. Recently the IAEA and the AAPM published the absorbed dose to water-based dosimetry protocol. In this work web-based dose calibration program for IAEA TRS-398 and AAPM TG-51 protocols were developed. This program developed using the Visual C# language can be used in the internet. User selectable dosimetry protocol on the web allows the absorbed dose to water data of the two protocols at a reference point to be easily compared, and enables to conveniently manage and understand the current status of the dosimetry calibration performed at participating institutions in korea. This program and the resultant database from the web-based calibration can be useful in developing new dosimetry protocols in Korea.

The Effect of Low Dose Radiation on the Neuronal Cell Proliferation in Diabetic Rats / 대한방사선종양학회지

PURPOSE: To investigate the effect of low dose radiation on neuronal cell proliferation in diabetic rats. MATERIALS AND METHODS: A group of rats (first group) were divided into three subgroups (nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy groups) to determine the effect of radiation on normal hippocampal neuronal cell proliferation. A further group of rats (second group) were divided into six subgroups (nondiabetic control, diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy groups) to determine the effect of radiation on hippocampal neuronal cell proliferation under diabetic conditions. Using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), the number of neuronal cells in the dentate gyrus of all the groups was counted. RESULTS: The number of BrdU-positive cells in the dentate Gyrus of the nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy subgroups of the first group were 45.96+/-3.42, 59.34+/-5.20 and 19.26+/-2.98/mm2, respectively. The number of BrdU-positive cells in the dentate gyrus of the diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy subgroups of the second group were 55.44+/-8.57, 33.33+/-6.46, 67.75+/-10.54, 66.63+/-10.05, 23.59+/-6.37 and 14.34+/-7.22/mm2, respectively. CONCLUSION: Low dose radiation enhances cell proliferation in the dentate gyrus of STZ-induced diabetic rats.

The Effect of Low Dose Radiation on the Neuronal Cell Proliferation in Diabetic Rats / 대한방사선종양학회지

PURPOSE: To investigate the effect of low dose radiation on neuronal cell proliferation in diabetic rats. MATERIALS AND METHODS: A group of rats (first group) were divided into three subgroups (nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy groups) to determine the effect of radiation on normal hippocampal neuronal cell proliferation. A further group of rats (second group) were divided into six subgroups (nondiabetic control, diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy groups) to determine the effect of radiation on hippocampal neuronal cell proliferation under diabetic conditions. Using immunohistochemistry for 5-bromo-2'-deoxyuridine (BrdU), the number of neuronal cells in the dentate gyrus of all the groups was counted. RESULTS: The number of BrdU-positive cells in the dentate Gyrus of the nondiabetic control, nondiabetic 0.1 Gy and nondiabetic 10 Gy subgroups of the first group were 45.96+/-3.42, 59.34+/-5.20 and 19.26+/-2.98/mm2, respectively. The number of BrdU-positive cells in the dentate gyrus of the diabetic control, diabetic 0.01 Gy, diabetic 0.1 Gy, diabetic 1 Gy and diabetic 10 Gy subgroups of the second group were 55.44+/-8.57, 33.33+/-6.46, 67.75+/-10.54, 66.63+/-10.05, 23.59+/-6.37 and 14.34+/-7.22/mm2, respectively. CONCLUSION: Low dose radiation enhances cell proliferation in the dentate gyrus of STZ-induced diabetic rats.

The Effect of Radiation Therapy on Hemophilic Arthropathy / 대한방사선종양학회지

PURPOSE: Repetitive bleeding into the joint space is the cause of debilitative hemophilic arthropathy. To interrupt this process, we treated the hemophilic patients suffering from repetitive joint bleeding with radiation therapy. MATERIALS AND METHODS: From 1997 to 2001, a total of 41 joints from 37 hemophilic arthropathy patients were treated with radiation therapy at Kyung Hee University Hospital. The treated joints were 35 ankles, 3 knees and 3 elbows, respectively. The age of the patients ranged from 4 to 27 years (median age: 11 years). The radiation dose ranged from 900 cGy to 2360 cGy (median dose: 900cGy). The fraction size was 150 cGy, 180 cGy or 200 cGy. The number of bleeding in one year before and after radiotherapy was compared. RESULTS: There was a tendency of frequent bleeding for the patients younger than 11 (p=0.051) but there was also a tendency for more improvement in this group (p=0.057). The number of joint bleedings was related with joint pain (p=0.012) and joint swelling (p=0.033) but not with the Arbold-Hilgartner stage (p=0.739), cartilage destruction (p=0.718) and synovial hypertrophy (p=0.079). The number of bleeding was reduced in thirty-three cases, and eight cases showed no improvement after radiation therapy. The average number of bleeding in a month was 2.52 before radiotherapy, but this was reduced to 1.4 after radiotherapy (p=0.017). CONCLUSION: Radiation therapy was effective for the hemophilia patients with repetitive joint bleeding to decrease the bleeding frequency and to prevent hemophilic arthropathy.

The Prognostic Effect of VEGF Expression in Squamous Cell Carcinoma of the Cervix Treated with Radiation Therapy Alone

We investigated the relationship between vascular endothelial growth factor (VEGF) expression and clinical outcome in squamous cell carcinoma of the cervix treated with radiotherapy alone. The immunohistochemical study was performed for fortytwo paraffin embedded specimens with anti-VEGF mouse monoclonal antibody. Staining was defined as positive for VEGF when more than 10% of the tumor cells were stained from 500 cells counted. Positive VEGF expression was observed in twenty-one among forty-two patients. VEGF expression according to stage (p=0.101), lymph node status (p=0.621), parametrial invasion (p=0.268), and age (p=0.5) revealed no significant difference. But the VEGF expression was significantly higher in tumors larger than 4 cm (p=0.031). Five year survival rates according to VEGF expression status were 89% for VEGF negative group and 47% for VEGF positive group (p=0.02). FIGO stage (p=0.007), tumor size (p=0.025) and the duration of external beam radiation therapy (p=0.006) were also significant prognostic factors for overall survival. We suggest that VEGF expression may be a prognotic factor of the cervix cancer patients treated with radiation therapy alone.

Clinical Implications of VEGF and p53 Expression in Squamous Cell Carcinoma of the Cervix Treated with Radiation Therapy / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The present study was designed to analyze the relationship between vascular endothelial growth factor (VEGF) and p53, and their impact on clinical outcome in squamous cell carcinoma of the cervix treated with radiation therapy. MATERIALS AND METHODS: This immunohistochemical study involved 23 patients with available paraffin blocks among 46 patients who were treated during the period from 1994 to 1997 in Eulji University Hospital in Korea. Anti-VEGF mouse monoclonal antibody and DO-7 anti- p53 mouse monoclonal antibody were used as the primary antibodies. Antibody binding was detected with a LSAB kit. Staining was defined as positive for VEGF and p53, when more than 10% and 5% of the tumor cells were stained out of 500 cells counted, respectively. RESULTS: FIGO stage (p=0.05) and tumor size (p=0.04) were significant prognostic factors for survival. p53 expression was present in 17 (77%) cases. There was no significant relationship between p53 staining and the clinicopathologic factors, such as FIGO stage (p=0.98), tumor size (p=0.43), lymph node status (p=0.82), parametrial invasion (p=0.96), and age (p=0.18). The five year survival rates according to the p53 expression status were 80% for the p53 negative group and 66% for the p53 positive group (p=0.58). Positive VEGF expression was observed in 11 (47%) of the total of 23 patients. Statistical evaluation of VEGF expression according to stage (p=0.36), tumor size(p=0.11), lymph node status (p=0.82), parametrial invasion (p=0.49), and age (p=0.55) revealed no significant difference in any of these parameters. The five year survival rates according to the VEGF expression status were 89% for the VEGF negative group and 41% for the VEGF positive group (p=0.07). CONCLUSION: We suggest that VEGF expression may have an effect on the prognosis of cervix cancer patients treated with radiation therapy, and further evaluation with a large sample size is warranted.

Suggestion of Optimal Radiation Fields in Rectal Cancer Patients after Surgical Resection for the Development of the Patterns of Care Study / 대한방사선종양학회지

PURPOSE: To suggest the optimal radiation fields after a surgical resection based on a nationwide survey on the principles of radiotherapy for rectal cancer in the Korean Patterns of Care Study. MATERIALS AND METHODS: A consensus committee, composed of radiation oncologists from 18 hospitals in Seoul Metropolitan area, developed a survey format to analyze radiation oncologist's treatment principles for rectal cancer after a surgical resection. The survey format included 19 questions on the principles of defining field margins, and was sent to the radiation oncologists in charge of gastrointestinal malignancies in all Korean hospitals (48 hospitals). Thirty three (69%) oncologists replied. On the basis of the replies and literature review, the committee developed guidelines for the optimal radiation fields for rectal cancer. RESULTS: The following guidelines were developed: superior border between the lower tip of the L5 vertebral body and upper sacroiliac joint; inferior border 2~3 cm distal to the anastomosis in patient whose sphincter was saved, and 2~3 cm distal to the perineal scar in patients whose anal sphincter was sacrificed; anterior margin at the posterior tip of the symphysis pubis or 2~3 cm anterior to the vertebral body, to include the internal iliac lymph node and posterior margin 1.5~2 cm posterior to the anterior surface of the sacrum, to include the presacral space with enough margin. Comparison with the guidelines, the replies on the superior margin coincided in 23 cases (70%), the inferior margin after sphincter saving surgery in 13 (39%), the inferior margin after abdominoperineal resection in 32 (97%), the lateral margin in 32 (97%), the posterior margins in 32 (97%) and the anterior margin in 16 (45%). CONCLUSION: These recommendations should be tailored to each patient according to the clinical characteristics such as tumor location, pathological and operative findings, for the optimal treatment. The adequacy of these guidelines should be proved by following the Korean Patterns of Care Study.

Survey on Radiotherpy Protocols for the Rectal Cancers among the Korean Radiation Oncologists in 2002 for the Development of the Patterns of Care Study of Radiation Therapy / 대한방사선종양학회지

PURPOSE: To conduct a nationwide survery on the principles in radiotherapy for rectal cancer, and develop the framework of a database of Korean Patterns of Care Study. MATERIALS AND METHODS: A consensus committee was established to develop a tool for measuring the patterns in radiotherapy protocols for rectal cancer. The panel was composed of radiation oncologists from 18 hospitals in Seoul Metropolitan area. The committee developed a survey format to analyze radiation oncologist's treatment principles for rectal cancer. The survey items developed for measuring the treatment principles were composed of 1) 8 eligibility criteria, 2) 20 items for staging work-ups and prognostic factors, 3) 7 items for principles of combined surgery and chemotherapy, 4) 9 patient set-ups, 5) 19 determining radiation fields, 6) 5 radiotherapy treatment plans, 7) 4 physical/laboratory examination to monitor a patient's condition during treatment, and 8) 10 follow-up evaluations. These items were sent to radiation oncologists in charge of gastrointestinal malignancies in all hospitals (48 hospitals) in Korea to which 30 replies were received (63%). RESULTS: Most of the survey items were replied to without no major differences between the repliers, but with the following items only 50% of repliers were in agreement:1) indications of preoperative radiation, 2) use of endorectal ultrasound, CT scan, and bone scan for staging work-ups, 3) principles of combining chemotherapy with radiotherapy, 4) use of contrast material for small bowel delineation during simulation, 5) determination of field margins, and 6) use of CEA and colonoscopy for follow-up evaluations. CONCLUSION: The items where considerable disagreement was shown among the radiation oncologists seemed to make no serious difference in the treatment outcome, but a practical and reasonable consensus should be reached by the committee, with logical processes of agreement. These items can be used for a basic database for the Patterns of Care Study, which will survey the practical radiotherapy patterns for rectal cancer in Korea.

Development of a Dose Calibration Program for Various Dosimetry Protocols in High Energy Photon Beams / 대한방사선종양학회지

PURPOSE: To develop a dose calibration program for the IAEA TRS-277 and AAPM TG-21, based on the air kerma calibration factor (or the cavity-gas calibration factor), as well as for the IAEA TRS-398 and the AAPM TG-51, based on the absorbed dose to water calibration factor, so as to avoid the unwanted error associated with these calculation procedures. MATERIALS AND METHODS: Currently, the most widely used dosimetry protocols of high energy photon beams are the air kerma calibration factor based on the IAEA TRS-277 and the AAPM TG-21. However, this has somewhat complex formalism and limitations for the improvement of the accuracy due to uncertainties of the physical quantities. Recently, the IAEA and the AAPM published the absorbed dose to water calibration factor based, on the IAEA TRS-398 and the AAPM TG-51. The formalism and physical parameters were strictly applied to these four dose calibration programs. The tables and graphs of physical data and the information for ion chambers were numericalized for their incorporation into a database. These programs were developed user to be friendly, with the Visual C++ language for their ease of use in a Windows environment according to the recommendation of each protocols. RESULTS: The dose calibration programs for the high energy photon beams, developed for the four protocols, allow the input of informations about a dosimetry system, the characteristics of the beam quality, the measurement conditions and dosimetry results, to enable the minimization of any inter-user variations and errors, during the calculation procedure. Also, it was possible to compare the absorbed dose to water data of the four different protocols at a single reference points. CONCLUSION: Since this program expressed information in numerical and data-based forms for the physical parameter tables, graphs and of the ion chambers, the error associated with the procedures and different user could be solved. It was possible to analyze and compare the major difference for each dosimetry protocol, since the program was designed to be user friendly and to accurately calculate the correction factors and absorbed dose. It is expected that accurate dose calculations in high energy photon beams can be made by the users for selecting and performing the appropriate dosimetry protocol.