Dosimetric Effects of Magnetic Resonance Imaging-assisted Radiotherapy Planning: Dose Optimization for Target Volumes at High Risk and Analytic Radiobiological Dose Evaluation

Based on the assumption that apparent diffusion coefficients (ADCs) define high-risk clinical target volume (aCTVHR) in high-grade glioma in a cellularity-dependent manner, the dosimetric effects of aCTVHR-targeted dose optimization were evaluated in two intensity-modulated radiation therapy (IMRT) plans. Diffusion-weighted magnetic resonance (MR) images and ADC maps were analyzed qualitatively and quantitatively to determine aCTVHR in a high-grade glioma with high cellularity. After confirming tumor malignancy using the average and minimum ADCs and ADC ratios, the aCTVHR with double- or triple-restricted water diffusion was defined on computed tomography images through image registration. Doses to the aCTVHR and CTV defined on T1-weighted MR images were optimized using a simultaneous integrated boost technique. The dosimetric benefits for CTVs and organs at risk (OARs) were compared using dose volume histograms and various biophysical indices in an ADC map-based IMRT (IMRTADC) plan and a conventional IMRT (IMRTconv) plan. The IMRTADC plan improved dose conformity up to 15 times, compared to the IMRTconv plan. It reduced the equivalent uniform doses in the visual system and brain stem by more than 10% and 16%, respectively. The ADC-based target differentiation and dose optimization may facilitate conformal dose distribution to the aCTVHR and OAR sparing in an IMRT plan.

Detection of Cryptosporidium parvum in Environmental Soil and Vegetables

Cryptosporidium parvum is a zoonotic protozoan parasite that causes cryptosporidial enteritis. Numerous outbreaks of cryptosporidiosis have been reported worldwide. Cryptosporidium is transmitted to hosts via consumption of contaminated water and food but also by direct contact with contaminated soil or infected hosts. The present study investigated farm soil collected from 34 locations along the western Korean peninsula and 24 vegetables purchased from local grocery markets in Seoul. The soil and vegetable samples were examined by real-time polymerase chain reaction (qPCR) to estimate the risk of infection. Eleven of 34 locations (32.4%) and 3 of 24 vegetable samples (12.5%) were contaminated with Cryptosporidium parvum, as confirmed by TaqI enzyme digestion of qPCR products and DNA sequencing. It is suggested that Cryptosporidium infection can be mediated via farm soil and vegetables. Therefore, it is necessary to reduce contamination of this organism in view of public health.

Multiple Spinal Cord Recurrences of an Intracranial Ependymoma after 14 Years

Ependymoma can spread via cerebrospinal fluid, but late spinal recurrences of intracranial tumor are very rare. We describe a case of a 33-year-old male who presented with multiple, delayed, recurrent lesions in the spinal cord from an intracranial ependymoma. The patient underwent gross total resection and postoperative radiation therapy 14 years prior to visit for a low grade ependymoma in the 4th ventricle. The large thoraco-lumbar intradural-extramedullary spinal cord tumor was surgically removed and the pathologic diagnosis was an anaplastic ependymoma. An adjuvant whole-spine radiation therapy for residual spine lesions was performed. After completion of radiation therapy, a MRI showed a near complete response and the disease was stable for three years.

Development of Preliminary Quality Assurance Software for GafChromic(R) EBT2 Film Dosimetry / 의학물리

Software for GafChromic EBT2 film dosimetry was developed in this study. The software provides film calibration functions based on color channels, which are categorized depending on the colors red, green, blue, and gray. Evaluations of the correction effects for light scattering of a flat-bed scanner and thickness differences of the active layer are available. Dosimetric results from EBT2 films can be compared with those from the treatment planning system ECLIPSE or the two-dimensional ionization chamber array MatriXX. Dose verification using EBT2 films is implemented by carrying out the following procedures: file import, noise filtering, background correction and active layer correction, dose calculation, and evaluation. The relative and absolute background corrections are selectively applied. The calibration results and fitting equation for the sensitometric curve are exported to files. After two different types of dose matrixes are aligned through the interpolation of spatial pixel spacing, interactive translation, and rotation, profiles and isodose curves are compared. In addition, the gamma index and gamma histogram are analyzed according to the determined criteria of distance-to-agreement and dose difference. The performance evaluations were achieved by dose verification in the 60o-enhanced dynamic wedged field and intensity-modulated (IM) beams for prostate cancer. All pass ratios for the two types of tests showed more than 99% in the evaluation, and a gamma histogram with 3 mm and 3% criteria was used. The software was developed for use in routine periodic quality assurance and complex IM beam verification. It can also be used as a dedicated radiochromic film software tool for analyzing dose distribution.

Development of the Multi-Parametric Mapping Software Based on Functional Maps to Determine the Clinical Target Volumes / 의학물리

To determine the clinical target volumes considering vascularity and cellularity of tumors, the software was developed for mapping of the analyzed biological clinical target volumes on anatomical images using regional cerebral blood volume (rCBV) maps and apparent diffusion coefficient (ADC) maps. The program provides the functions for integrated registrations using mutual information, affine transform and non-rigid registration. The registration accuracy is evaluated by the calculation of the overlapped ratio of segmented bone regions and average distance difference of contours between reference and registered images. The performance of the developed software was tested using multimodal images of a patient who has the residual tumor of high grade gliomas. Registration accuracy of about 74% and average 2.3 mm distance difference were calculated by the evaluation method of bone segmentation and contour extraction. The registration accuracy can be improved as higher as 4% by the manual adjustment functions. Advanced MR images are analyzed using color maps for rCBV maps and quantitative calculation based on region of interest (ROI) for ADC maps. Then, multi-parameters on the same voxels are plotted on plane and constitute the multi-functional parametric maps of which x and y axis representing rCBV and ADC values. According to the distributions of functional parameters, tumor regions showing the higher vascularity and cellularity are categorized according to the criteria corresponding malignant gliomas. Determined volumes reflecting pathological and physiological characteristics of tumors are marked on anatomical images. By applying the multi-functional images, errors arising from using one type of image would be reduced and local regions representing higher probability as tumor cells would be determined for radiation treatment plan. Biological tumor characteristics can be expressed using image registration and multi-functional parametric maps in the developed software. The software can be considered to delineate clinical target volumes using advanced MR images with anatomical images.

Dosimetric Characteristics of Edge Detector(TM) in Small Beam Dosimetry / 의학물리

In this study, we evaluated an edge detector for small-beam dosimetry. We measured the dose linearity, dose rate dependence, output factor, beam profiles, and percentage depth dose using an edge detector (Model 1118 Edge) for 6-MV photon beams at different field sizes and depths. The obtained values were compared with those obtained using a standard volume ionization chamber (CC13) and photon diode detector (PFD). The dose linearity results for the three detectors showed good agreement within 1%. The edge detector had the best linearity of +/-0.08%. The edge detector and PFD showed little dose rate dependency throughout the range of 100~600 MU/min, while CC13 showed a significant discrepancy of approximately -5% at 100 MU/min. The output factors of the three detectors showed good agreement within 1% for the tested field sizes. However, the output factor of CC13 compared to the other two detectors had a maximum difference of 21% for small field sizes (~4x4 cm2). When analyzing the 20~80% penumbra, the penumbra measured using CC13 was approximately two times wider than that using the edge detector for all field sizes. The width measured using PFD was approximately 30% wider for all field sizes. Compared to the edge detector, the 10~90% penumbras measured using the CC13 and PFD were approximately 55% and 19% wider, respectively. The full width at half maximum (FWHM) of the edge detector was close to the real field size, while the other two detectors measured values that were 8~10% greater for all field sizes. Percentage depth doses measured by the three detectors corresponded to each other for small beams. Based on the results, we consider the edge detector as an appropriate small-beam detector, while CC13 and PFD can lead to some errors when used for small beam fields under 4x4 cm2.

Statistical Errors in Papers Published in the Journal of the Korean Society for Therapeutic Radiology and Oncology / 대한방사선종양학회지

PURPOSE: To improve the quality of the statistical analysis of papers published in the Journal of the Korean Society for Therapeutic Radiology and Oncology (JKOSTRO) by evaluating commonly encountered errors. MATERIALS AND METHODS: Papers published in the JKOSTRO from January 2006 to December 2007 were reviewed for methodological and statistical validity using a modified version of Ahn's checklist. A statistician reviewed individual papers and evaluated the list items in the checklist for each paper. To avoid the potential assessment error by the statistician who lacks expertise in the field of radiation oncology; the editorial board of the JKOSTRO reviewed each checklist for individual articles. A frequency analysis of the list items was performed using SAS (version 9.0, SAS Institute, NC, USA) software. RESULTS: A total of 73 papers including 5 case reports and 68 original articles were reviewed. Inferential statistics was used in 46 papers. The most commonly adopted statistical methodology was a survival analysis (58.7%). Only 19% of papers were free of statistical errors. Errors of omission were encountered in 34 (50.0%) papers. Errors of commission were encountered in 35 (51.5%) papers. Twenty-one papers (30.9%) had both errors of omission and commission. CONCLUSION: A variety of statistical errors were encountered in papers published in the JKOSTRO. The current study suggests that a more thorough review of the statistical analysis is needed for manuscripts submitted in the JKOSTRO.

Development of Phantom and Comparison Analysis for Performance Characteristics of MOSFET Dosimeter / 의학물리

This study is to develope a phantom for MOSFET (Metal Oxide Semiconductors Field Effect Transistors) dosimetry and compare the dosimetric properties of standard MOSFET and microMOSFET with the phantom. In this study, the developed phantom have two shape: one is the shape of semi-sphere with 10 cm diameters and the other one is the flat slab of 30 cm x 30 cm with 1 cm thickness. The slab phantom was used for calibration and characterization measurements of reproducibility, linearity and dose rate dependency. The semi-sphere phantom was used for angular and directional dependence on the types of MOSFETs. The measurements were conducted under 10 x 10 cm2 fields at 100 cm SSD with 6 MV photon of Clinac (21EX, Varian, USA). For calibration and reproducibility, five standard MOSFETs and microMOSFETs were repeatedly irradiated by 200 cGy five times. The average calibration factor was a range of 1.09+/-0.01~1.12+/-0.02 mV/cGy for standard MOSFETs and 2.81+/-0.03~2.85+/-0.04 mV/cGy for microMOSFETs. The response of reproducibility in the two types of MOSFETs was found to be maximum 2% variation. Dose linearity was evaluated in the range of 5 to 600 cGy and showed good linear response with R2 value of 0.997 and 0.999. The dose rate dependence of standard MOSFET and microMOSFET was within 1% for 200 cGy from 100 to 600 MU/min. For linearity, reproducibility and calibration factor, two types of MOSFETs showed similar results. On the other hand, the standard MOSFET and microMOSFET were found to be remarkable difference in angular and directional dependence. The measured angular dependence of standard MOSFET and microMOSFET was also found to be the variation of 13%, 10% and standard deviation of +/-4.4%, +/-2.1%. The directional dependence was found to be the variation of 5%, 2% and standard deviation of +/-2.1%, +/-1.5%. Therefore, dose verification of radiation therapy used multidirectional X-ray beam treatments allows for better the use of microMOSFET which has a reduced angular and directional dependence than that of standard MOSFET.

Leptomycin B Increases Radiosensitization by Trichostain A in HeLa Cells / 대한방사선종양학회지

PURPOSE: Histone deacetylase inhibitors (HDIs) are emerging as potentially useful components of anticancer therapy and their radiosensitizing effects have become evident. Specific HDIs are now available that preferentially inhibit specific HDAC classes; TSA inhibits Class I and II HDACs, and SK7041 inhibits Class I HDACs. MATERIALS AND METHODS: We tested the differential radiosensitization induced by two different classes of HDIs in HeLa cells. We next tested the hypothesis that p53 expression in cancer cells may influence the susceptibility to HDIs by using pharmacologic modification of the p53 status under an isogenic background. RESULTS: It is interesting that p53 expression in the HeLa cells clearly increased the degree of radiosensitization by TSA compared to that of the class I specific inhibitor SK7041. This suggests that p53 may, in part, be responsible for the mechanistic role for the greater radiosensitization induced by Class I & II inhibitors compared to that of the class I specific inhibitors. Thus, these studies are useful in distinguishing between events mediated solely by the Class I HDACs versus those events involving the other classes of HDACs as well. CONCLUSION: The anticancer efficacy of targeting Class I and II HDACs, in conjunction with radiation therapy, may be further enhanced by the restoration of p53 expression.

Outcome and Prognostic Factors of Childhood Diffuse Brainstem Glioma / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The outcome and prognostic factors of brainstem glioma were evaluated following radiotherapy methods. MATERIALS AND METHODS: Between 1986 and 2001, 45 childhood patients with diffuse brainstem glioma were treated. There were 26 boys and 19 girls, with a median age of 7 years (range 3~18). The histopathological diagnoses were confirmed in 13 patients, which revealed a low-grade glioma in four patients, and high-grade glioma in the other nine. Before 1993, radiation therapy using a regime of 1.8 to 2.0 Gy once a day was performed in 16 cases; thereafter, a regimes of 1.1 or 1.5 Gy twice a day was given in 15 and 14 cases, respectively. Nine patients were treated with adjuvant chemotherapy. The response to the treatment was evaluated by the MRI findings 4 weeks after radiotherapy. RESULTS: After radiotherapy, the neurological deficit improved in 42 of the 45 patients (93%). The MRI responses were as follows; partial response 22/39 (56%), minimal to no response in 16/39 (41%) and tumor progression in 1/39 (3%). The median time to disease progression was 7 months, and the median survival was 12 months; the overall survival rate at 1 year was 41%. There was no significant prognostic factor for overall survival. The progression-free survival was influenced by the tumor histology (low grade vs. high grade, p=0.05) in those patients whose pathology was confirmed. CONCLUSION: The radiation therapy fractionation schedule did not influence the survival. Low grade histology was a possible favorable prognostic factor of progression-free survival in pediatric brainstem glioma patients.

A Histone Deacetylase Inhibitor, Trichostatin A, Enhances Radiosensitivity by Abrogating G2/M Arrest in Human Carcinoma Cells / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Histone deacetylase inhibitors (HDIs) are emerging as potentially useful components in anticancer therapy. In this study, we tried to confirm the radiosensitizing effect of trichostatin A (TSA) on a panel of human carcinoma cell lines and elucidate its mechanism of interaction. MATERIALS AND METHODS: A549, HeLa and Caski cells were exposed to TSA for 18 hr prior to irradiation, and the cell survival then measured using a clonogenic assay. Western blot and flow cytometric analyses, for histone acetylation, and cell cycle and apoptosis, respectively, were also performed. RESULTS: TSA increased the acetylation of histone H3. The pretreatment of TSA consistently radiosensitized all three cell lines. The SF2 (surviving fraction at 2 Gy) of TSA-treated cells was significantly lower than that of mock treated cells. The SER (sensitizer enhancement ratio) increased in all 3 cell lines, in concentration dependent manners. The TSA treated cells showed abrogation of radiation-induced G2/M arrest, in a concentration dependent manner. CONCLUSION: The pretreatment of TSA enhanced the radiosensitivity of a panel of human carcinoma cells, which was attributed, in part, to the abrogation of radiationinduced G2/M arrest.

Comparison of Enhanced Dynamic Wedge with Physical Metal Wedge based on the Basic Dosimetric Parameters / 의학물리

For clinical implementation of Enhanced Dynamic Wedge (EDW), it is necessary to adequately analyze and commission its dosimetric properties in comparison to common physical metal wedge (MTW). This study was implemented with the essential measurements of parameters for clinical application, such as percentage depth dose, peripheral dose, surface dose, effective wedge factor, and wedge profile. In addition, through the comparison study of EDW with open and MTW, the analysis was performed to characterize the EDW. We also compared EDW dose profiles of measured values using chamber array 24 (CA24) with calculated values using radiation treatment planning system. PDDs of EDW showed good agreements between 0.2~0.5% of open beam, but 2% differences with MTW. In the result of the measurements of peripheral dose, it was shown that MTW was about 1% higher than open field and EDW. The surface doses of 60degrees MTW showed 10% lower than the others. We found that effective wedge factor of EDW had linear relationships according to Y jaw sizes and was independent of X jaw sizes and was independent of X jaw sizes and asymmetric Y jaw opening. In comparison with measured values and calculate values from Golden-STT based radiation treatment planning system (RTP system), it showed very good agreement within difference of 1%. It could be concluded that EDW is a very reliable and useful tool as a beam modification substitute for conventional MTW.

An Effect of Time Gating Threshold (TGT) on the Delivered Dose at Internal Organ with Movement due to Respiration / 의학물리

In this study, we investigated the effect of time gating threshold on the delivered dose at a organ with internal motion by respiration. Generally, the internal organs have minimum motion at exhalation during normal breathing. Therefore to compare the dose distribution time gating threshold, in this paper, was determined as the moving region of target during 1 sec at the initial position of exhalation. The irradiated fields were then delivered under three conditions; 1) non-moving target 2) existence of the moving target in the region of threshold (1sec), 3) existence of the moving target region out of threshold (1.4 sec, 2 sec). And each of conditions was described by the moving phantom system. It was compared with the dose distributions of three conditions using film dosimetry. Although the treatment time increased when the dose distributions was obtained by the internal motion to consider the TGT, it could be obtained more exact dose distribution than in the treatment field that didn't consider the internal motion. And it could be reduced the unnecessary dose at the penumbra region. When we set up 1.4 sec of threshold, to reduce the treatment time, it could not be obtained less effective dose distribution than 1 sec of threshold. Namely, although the treatment time reduce, the much dose was distributed out of the treatment region. Actually when it is treated the moving organ, it would rather measure internal motion and external motion of the moving organ than mathematical method. If it could be analyzed the correlation of the internal and external motion, the treatment scores would be improved.

Outcome of LINAC Radiosurgery for a Cavernous Angioma / 대한방사선종양학회지

PURPOSE: To establish the role of stereotactic radiosurgery using a linear accelerator for the treatment of patients with cavernous angioma. MATERIALS AND METHODS: Between February 1995 and May 1997, 11 patients with cavernous angioma were treated with stereotactic radiosurgery using a linear accelerator. Diagnoses were based on the magnetic resonance imaging in 8 patients, and the histological in 3. The vascular lesions were located in the brainstem (5 cases), cerebellum (2 cases) thalamus (1 case) and cerebrum (3 cases). The clinical presentation at onset included previous intracerebral hemorrhages (9 cases) and seizures (2 cases). All patients were treated with a a linac-based radiosurgery. The median dose of radiation delivered was 16 Gy ranging from 14 to 24 Gy, which was typically prescribed to the 80% isodose surface (range 50~80%), corresponding to the periphery of the lesion with a single isocenter. Ten patients were followed-up. RESULTS: The median follow-up was 49 months ranging from 8 to 73 months, during which time two patients developed an intracerebral hemorrhage, 1 at 8 months, with the other at 64 months post radiosurgery. One patient developed neurological deficit after radiosurgery, and two developed an edema on the T2 weighted images of the MRI surrounding the radiosurgical target. CONCLUSION: The use of stereotactic radiosurgery in the treatment of a cavernous angioma may be effective in the prevention of rebleeding, and can be safely delivered. However, a longer follow-up period will be required.

Treatment Outcome of Brain Metastasis after the Cranial Radiotherapy Followed by Fractionated Stereotactic Radiotherapy and Its Prognostic Factors / Journal of the Korean Cancer Association, 대한암학회지

To evaluate the effectiveness of whole brain radiotherapy followed by stereotactic radiotherapy for newly diagnosed brain metastasis. MATERIALS AND METHODS: Thirty-three metastatic brain tumors received radiotherapy to the whole brain and stereotactic radiotherapy in 25 patients. Lung carcinomas were the most common (17/25) primary tumor. The radiation dose was 30 to 40 Gy for the whole brain, with a 12 to 40 Gy boost to the metastatic foci. Survival and local control rates were determined, and the prognostic factors for survival were evaluated. RESULTS: The overall median survival was 15 months and the actuarial survivals at 1- and 2-year were 67% and 31%, respectively. The local tumor control rate was 79%, with a median follow-up period of 9 months (2~36 months). The prognostic factors associated with survival were age, tumor size and the existence of active extracranial metastasis, with the performance status showing marginal significance. No acute or chronic complications were observed in the patients. CONCLUSION: From our data, cranial radiotherapy followed by stereotactic radiotherapy was useful in the local control of metastatic tumors, and in the survival of patients with tumor factors, such as small size or the absence of extracranial tumor activity, and host factors, such as young age or good performance status.

Cranial Irradiation in the Management of Childhood Leukemic Hyperleukocytosis / 대한방사선종양학회지

PURPOSE: Acute leukemia with hyperleukocytosis (more than 105/mm3) is at high risk of early sudden death, usually from intracerebral hemorrhage. Emergency cranial irradiation is a relatively simple approach to solve this the problem. We summarized our experience of cranial irradiation in 24 leukemic children who presented with hyperleukocytosis. METHODS AND MATERIALS: Between 1990 and 1998, 40 children with acute leukemia presenting with hyperleukocytosis were referred for emergency cranial irradiation. Among these patients, 24 children were evaluable. There were 16 boys and eight girls, their ages ranged from 2 to 13 years (median 9.5 years). The initial leukocyte counts ranged 109,910/mm3 to 501,000/mm3. Peripheral blood smear was performed in all patients and noted the morphology of the blast. Introduction of emergency cranial irradiation was determined by the leukocyte counts (more than 100,000/mm) and the existence of the blast in peripheral blood smear. All patients were treated with intravenous hydration with alkaline fluid and oral allopurinol. Cranial irradiation started on the day of diagnosis. With 2 Gy in one fraction in 4 patients, 4 Gy in two fractions in 20 patients. RESULTS: The WBC count had fallen in 19 patients (83%) and no intracerebral hemorrhage occurred after irradiation. There were five cases of early deaths. Four patients died of metabolic complications, and one patient with intracerebral hemorrhage. He died 5 hours after cranial irradiation. No patient had any immediate side effect from cranial irradiation. CONCLUSION: Our data suggest, that emergency cranial irradiation can be safely chosen and effective in childhood leukemic patients presenting with high leukocyte counts.

The Optimal Condition of Performing MTT Assay for the Determination of Radiation Sensitivity / 대한방사선종양학회지

PURPOSE: The measurement of radiation survival using a clonogenic assay, the established standard, can be difficult and time consuming. In this study, We have used the MTT assay, based on the reduction of a tetrazolium salt to a purple formazan precipitate by living cells, as a substitution for clonogenic assay and have examined the optimal condition for performing this assay in determination of radiation sensitivity. MATERIALS AND METHODS: Four human cancer cell lines-PCI-1, SNU-1066, NCI-H630 and RKO cells have been used. For each cell line, a clonogenic assay and a MTT assay using Premix WST-1 solution, which is one of the tetrazolium salts and does not require washing or solubilization of the precipitate were carried out after irradiation of 0, 2, 4, 6, 8, 10 Gy. For clonogenic assay, cells in 25 cm2 flasks were irradiated after overnight incubation and the resultant colonies containing more than 50 cells were scored after culturing the cells for 10~14 days. For MTT assay, the relationship between absorbance and cell number, optimal seeding cell number, and optimal timing of assay was determined. Then, MTT assay was performed when the irradiated cells had regained exponential growth or when the non-irradiated cells had undergone four or more doubling times. RESULTS: There was minimal variation in the values gained from these two methods with the standard deviation generally less than 5%, and there were no statistically significant differences between two methods according to t-test in low radiation dose (below 6 Gy). The regression analyses showed high linear correlation with the R2 value of 0.975~0.992 between data from the two different methods. The optimal cell numbers for MTT assay were found to be dependent on plating efficiency of used cell line. Less than 300 cells/well were appropriate for cells with high plating efficiency (more than 30%). For cells with low plating efficiency (less than 30%), 500 cells/well or more were appropriate for assay. The optimal time for MTT assay was after 6 doubling times for the results compatible with those of clonogenic assay, at least after 4 doubling times was required for valid results. In consideration of practical limits of assay (12 days, in this study) cells with doubling time more than 3 days were inappropriate for application. CONCLUSION: In conclusion, it is found that MTT assay can successfully replace clonogenic assay of tested cancer cell lines after irradiation only if MTT assay was undertaken with optimal assay conditions that included plating efficiency of each cell line and doubling time at least.

Hypofractionated Radiation Therapy for Early Glottic Cancer: Preliminary Results / 대한방사선종양학회지

PURPOSE: This study was performed for the evaluation of the feasibility and toxicity of hypofractionated radiation therapy for early glottic cancer METHODS AND MATERIALS: From February 1999 to February 2000, 20 patients with histologically confirmed Stage I, II glottic cancer were enrolled into this study. There were 18 males and 2 females, the median age of the patients was 59 years. The distribution of stage distribution was as follows; T1aN0-16 patients, T1bN0-1 patient, T2N0-3 patients. Eighteen patients underwent laryngomicroscopic biopsy only, and two patients underwent laser cordectomy. All patients received radical radiation therapy (2.5 Gy per fraction, 24 fractions, total 60 Gy). Median duration of treatment was 36 days (range 31-45 days). RESULTS: Radiation therapy were well tolerated. Most common acute reactions were odynophagia and hoarseness, and these reactions resolved after radiation therapy. There were one case of RTOG grade 3 odynophagia (5%), six cases of grade 3 hoarseness (30%). Response of radiation therapy was evaluated one month after completion of treatment. All patients revealed complete response. During follow up, total three cases of treatment failure were detected. two cases were local recurrence in 10 and 13 months of radiation therapy and one case was local recurrence and distant metastasis in 2 months of radiation therapy CONCLUSION: This hypofractionated radiation therapy schedule was feasible and effective for control of early glottic cancer. But longer follow up time would be required to assess the long-term disease control and the late complication by shortening radiation therapy duration.

Comparison of New AJCC Staging System with Old AJCC Staging System in Nasopharyngeal Carcinoma / 대한방사선종양학회지

PURPOSE: This study was designed to examine the reliability of the new version of the AJCC staging system (1997) of nasopharyngeal carcinoma in comparison with the AJCC staging system of 1992. MATERIALS AND METHODS: Between 1983 and 1996, 185 patients with histologically proven nasopharyngeal carcinoma were treated with radiation therapy at the Department of Therapeutic Radiology Seoul National University Hospital. For these patients, AJCC staging system of 1992 was compared with the 1997 version, by reviewing hospital records, computed tomography (CT) and/or magnetic resonance imaging (MRI). RESULTS: 5-year overall survival rates according to the 1992 and 1997 AJCC staging systems were 100%, and 100% at stage I; 100%, and 68.8% at stage II; 61.4%, and 63.8% at stage III; 61.1%, and 63.2% at stage IV. 5-year overall survival rates of each classification showed significant differences between stages ( p=0.0049 for the old version, p=0.01 for the new), but no significant difference was found between the staging systems except at stage II. CONCLUSION: The new AJCC staging system allows staging as reliably as the 1992 version, but the adequacy of the newly modified staging classification should be confirmed by further clinical examination.

Neoadjuvant Chemotherapy and Radiation Therapy inAdvanced Stage Nasopharyngeal Carcinoma / 대한방사선종양학회지

PURPOSE: To assess the feasibility and the toxicity of the neoadjuvant chemotherapy on the treatment of patients with locoregionally advanced nasopharyngeal carcinoma. MATERIALS AND METHODS: We analyzed 77 previouly untreated and histologically confirmed advanced stage nasopharyngeal carcinoma patients treated with neoadjuvant chemotherapy followed by radiation therapy at the Seoul National University Hospital between 1984 and 1996. The stage distribution was therapy at the Seoul National University Hospital between 1984 and 1996. The stage distribution was as follows : AJCC stage III-2, stage IV-75, Sixty-six patients received infusion of 5-FU (1000 mg/m2, on Day 1~5) and cisplatin (100 mg/m2, on Day 1), eleven patients received infusion of 5-FU (1000 mg/m2, on Day 1~5) and carboplatin (300 mg/m2, on Day 1), as neoadjuvant chemotherapy prior to radiation therapy. The median follow-up for surviving patients was 44 months. RESULTS: The overall chemotherapy response rates were 87%. The toxicities of chemotherapy were mild. Only 3 patients experienced Grade 3 toxicities (1 for cytopenia, 2 for nausea/vomiting). The degree of radiation induced mucositis was not severe, and then patients developed Grade 2 mucositis. The 5-year overall survival rates were 68% and the 5-year disease free survival rates were 65%. The 5-year overall survival rates were 68% and the 5-year disease free survival rates were 65%. The 5-year freedom from distant metastasis rates were 82% and 5-year locoregional control rates were 75%. CONCLUSION: This single institution experience suggests that neoadjuvant chemotherapy improves overall survival and disease free survival for patients with advanced stage nasopharyngeal carcinoma without increase of toxicity.