• Radiation Oncology Journal
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• v.27 no.3
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• pp.120-125
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• 2009

Purpose: We wanted to present the preliminary results of intensity-modulated radiotherapy (IMRT) for the treatment of tonsillar cancer. Materials and Methods: We retrospectively analyzed 12 patients who underwent IMRT for tonsillar cancer at Asan Medical Center between November 2002 and February 2007. Seven patients (58%) received definitive treatment, and five (42%) were treated in the postoperative setting. Among the definitively treated patients, 6 patients received cisplatin-based chemotherapy regimens. Simultaneous modulated accelerated radiation therapy (SMART) was used in nine patients. The prescribed dose was 72 Gy at 2.4 Gy/fraction for the definitively treated cases and 61.6 Gy at 2.2 Gy/fraction for the postoperative cases. The median follow-up period was 34 months. Results: All twelve patients completed treatment without interruption, and eleven showed a complete response. One patient had persistent loco-regional disease after treatment. The three-year estimates of loco-regional control, disease-free survival and overall survival were 91.7%, 91.7%, and 100%. The worst acute mucositis was Grade 1 in four patients, Grade 2 in five patients, Grade 3 in two patients and Grade 4 in one patient. Grade 3 xerostomia was observed in six patients. Conclusion: Intensity-modulated radiotherapy was shown to be a safe and effective treatment modality for tonsillar cancer. Further studies with a larger number of patients and a longer follow-up period are needed to evaluate the ultimate tumor control and late toxicity of IMRT for treating tonsillar cancer.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.9-15
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• 1996

Purpose: The traditional approach with surgery and/or radiotherapy(RT) for advanced head and neck cancer Provides anticipated cure rates of $10-65\%$ depending on stages and sites. Recently, combined modality with chemotherapy have been extensively investigated in attempts to improve survival and local control. We retrospectively analysed our experience of 31 patients with advanced head and neck cancer. Materials and Methods : November 1983 to October 1994. 31 Patients with Stage III and IV squamous cell head and neck cancer were treated with RT. Sixteen patients were treated with RT alone, and IS patients were treated with combined RT plus chemotherapy. All patients were treated with 4-MV LINAC and radiation dose ranged from 5000 cGy to 7760 cGy (median 7010 cGy). In combined group, 7 patients were treated with cisplatin plus 5-FU 2 patients were treated with methotrexate plus leucovorin plus 5-FU plus cisplatin or carboplatin, and 6 patients were treated with cisplatin as a radiosensitizer. Results : Median follow up period was 16 months (range 4-134 months). The major responses (CR+PR) were noted in 10 patient ($66.6\%$) of the RT alone group and 14 patient ($93.3\%$) of the chemoradiation group. There was no statistical difference in CR rate between the two groups The overall survival rates at 5 years were $23.4\%$ in the radiation alone group, $23.5\%$ in the chemoradiation group Disease-free survival rates at 3 years were $44.5\%$ in the radiation alone group, $40\%$ in the chemoradiation group. There was no statistical differences in overall survival rates and disease-free survival rates between the two groups. Local recurrences occurred in $71.5\%$ of the radiation alone group, $72.7\%$ of the chemoradiation group and distant metastasis occurred in $14.4\%$ of radiation alone group, $9.1\%$ of the chemoradiation group. The frequencies of complications were comparable in both groups except hematologic toxicity Conclusion : Total response rates in the combined chemotherapy and radiotherapy was relatively higher than radiotherapy alone. But our result failed to show any survival benefit of the combined chemotherapy and radiotherapy. The accrual of large number of patients and long term follow-un may be necessary to confirm the present result of combined chemotherapy and radiotherapy.

• Radiation Oncology Journal
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• v.21 no.1
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• pp.66-74
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• 2003

Purpose : The matrix metalloprotelnases (MMPs) are a family of enzymes whose main function is the degradation of the extracellular matrix. Several studies have revealed that MMPs and TIMPS are related to the wound heating process and in photoaging caused by ultraviolet Irradiation. However, the expressions of MMP and TIMP after irradiation have not, to the best of our knowledge, been studied. This study investigates the expressions of MMP-2 and TIMP-2 in rat Intestinal mucosa following irradiation. Materials and Methods : The entire abdomen of Sprague-Dawley rats was irradiated using a single dose method. The rats were sacrificed on day 1, 2, 3, 5, 7 and 14 following irradiation. Histopathological observations were made using hematoxilin & eosin staining. The expressions of MMP-2 and TIMP-2 were examined using immunohistochemistry, Irnrnunoblotting and ELISA. Results : Radiation induced damage associated with atrophic villi, and infiltration of inflammatory cell was observed from the first postirradiation day, and severe tissue damage was observed on the second and the third postirradiation days. An increase in mitosis and the number of regenerating crypts, as evidence of regeneration, were most noticeable on the fifth postirradiation day. From the immunohistochemlstry, the MMP-2 expression was observed from the first postirradiation day, but was most conspicuous on the third and the fifth postirradiation days. The TIMP-2 expression was most conspicuous on the fifth postirradiation day. From the irnrnunoblotting, the MMP-2 expression was strongly positive on the third postirradlatlon day, and that of TIMP-2 showed a strong positive response on the fifth postirradiation day. In ELISA tests, the expressions of MMP-2 and TIMP-2 were increased in the postirradiation groups compared to those of the normal controls, and showed a maximum increase on the fifth postirradiatlon day. These results were statistically significant. Conclusion : The expressions of MMP-2 and TIMP-2 were increased in the intestinal mucosa of the rats following irradiation, and these results correlated with the histopathological findings, such as tissue damage and regeneration. Therefore, this study suggests that MMP-2 and TIMP-2 play roles in the mechanisms of radiation-induced damage and regeneration of intestinal mucosa of rats.

• The Korean Journal of Nuclear Medicine
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• v.35 no.5
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• pp.301-312
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• 2001

Purpose: Stomach cancer is one of the most common malignancies in Korea, but there is no report on FDG PET in patients with stomach cancer. We observed findings of FDG PET in patients with stomach cancer. Materials and Methods: In 13 patients with pre-operative stomach cancer, PET and CT were performed. Primary lesion and regional lymph nodes detection were aualyzed. Correlation between FDG uptake ratio and each prognostic factor of primary lesion was analyzed. In 19 patients diagnosed as recurrence or displaying suspicious symptoms, conventional work up including tumor marker and PET were performed. Recurrence detection of anastomotic site, distant metastasis, and tumor marker elevation were analyzed. Results: Sensitivity for primary lesion detection was 83.3% (CT 71.4%) and two submucosal lesions were undetected. FDG uptake ratio was variable and had no correlation with invasion-depth, size, Borrmann type, staging and differentiation. Sensitivity for regional lymph node detection was 58.3% (CT 58.3%) and the lesions less than 1cm were undetected. Sensitivity for recurrence detection was 100% but there were three false positives. Sensitivity for distant metastasis detection was 64.3% and significantly higher than that of conventional work-up (21.4%). Average of tumor marker level in patients who were confirmed as recurrence was higher than false positive. Conclusion: PET is more useful than conventional work up in distant metastasis detection when recurrence is suspected. In pre-operative stomach cancer, PET is comparable to CT for detection of primary lesion and regional lymph node metastasis and detection of distant metastasis requires further study.

• Journal of Yeungnam Medical Science
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• v.20 no.2
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• pp.105-116
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• 2003

Definitely, treatment for gastric cancer is primarily surgical. Detection in early stage of disease and complete surgical resection is the best way to cure gastric cancer. If surgery is planned, careful preoperative evaluation and corrections of physiologic and psychologic abnormalities are essential to reduce perioperative morbidity or mortality. Basic principle of gastrectomy for gastric cancer is an en bloc resection of tumor with adequate margins of normal tissue and with regional lymph nodes and omental tissues. To complete these principles, regional lymph nodes and all omental tissues should be removed altogether during performing various types of gastric resection. The lymph node dissection is one of the most effective procedures for gastric cancer to achieve curative resection. The basic types of gastric resection are distal subtotal gastrectomy and total gastrectomy according to the condition of primary lesions and the status of lymph node metastases. When the primary lesion is located near the esophagogastric junction, it is sometimes hard for a surgeon to select adequate surgical method. Postoperative quality of life in a patient has become a very important factor to be considered in every step of surgical therapy. With increasing incidence of early gastric cancer, a number of surgical trials for limited surgery or endoscopic procedures have been performed, but the long-term clinical results should be carefully analyzed to define the clinical relevance of these new techniques. For patients with disseminated gastric cancer, a palliative procedure can be performed to improve quality of life of patients and to avoid immediate death due to the cancer-related complications.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.1
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• pp.18-23
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• 2000

The changes of the microorganism composition after therapeutic radiation for oral cancer patients are not well known and the long-term follow-up data are not reported. To obtain basic data for understanding of pathogenesis and prevention and treatment of dental caries and mucositis occuring after radiation therapy, 7 of the oral cancer patients presented at the Seoul National University Oral & Maxillofacial Department between 1997 and 1998 whose treatment plan included radiation therapy were recruited to investigate the changes in bacterial composition(total aerobic count, Candida, Staphylococci, Lactobacilli, S. mutans, and S. salivarius (mitis, sanguis)) of the saliva before, during, and after radiation therapy. The basic data obtained from this study on identification and composition change of the bacteria in saliva of patients treated with radiation therapy can be used (1) as a reference for deciding on the ideal anti-microbial spectrum of the oral rinsing agent to be used in patients treated with radiation therapy for malignant tumor of the head and neck region. (2) to enhance the understanding of increase of opportunistic infection after immunochemical changes of the saliva and its relation to specific bacterial infection. (3) as a reference in prescribing prophylactic antibiotics in immunodepressed patients after radiation therapy.

• Journal of Gastric Cancer
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• v.5 no.3 s.19
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• pp.200-205
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• 2005

Purpose: KLF4, a member of the KLF family, is a zinc finger tumor suppressor protein that is critical for gastric epithelial homeostasis. Our aim was to determine whether the altered expression of KLF4 might be associated with gastric cancer development and, if so, to determine to which pathologic parameter it is linked. Materials and Methods: For the construction of the gastric cancer tissue microarray, 84 paraffin-embedded tissues containing gastric cancer areas were cored 3 times and transferred to the recipient master block. The expression pattern of KLF4 was examined on tissue microarray slides by using immunohistochemistry and was compared with pathologic parameters, including histologic type, depth of invasion, lymph node metastasis, and peritoneal dissemination. Results: The KLF4 protein was expressed in cytoplasm and nucleus of superficial and foveolar epithelial cells in the normal gastric mucosa. We found markedly reduced or loss of KLF4 expression in 43 (51.2%) of the 84 gastric cancer tissues. There was no significant correlation between KLF4 expression and pathologic parameters, including histologic type, depth of invasion, lymph node metastasis and peritoneal dissemination. Conclusion: Our findings suggest that altered expression of KLF4 may contribute to abnormal regulation of gastrointestinal epithelial cell growth and differentiation and to the development of Korean gastric cancer, as an early event.

• Journal of Gastric Cancer
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• v.5 no.4 s.20
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• pp.295-303
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• 2005

The Korean laparoscopic Gastrointestinal Surgery Study Group made a survey of laparoscopic gastric surgeries which were performed in Korea during 2004. Thirty-eight surgeons from 36 Institutions responded to the questionnaires. One thousand eighty-nine laparoscopic gastric operations were performed during 2004. The cumulative number from 1995 to 2004 was about 2,386. Seven hundred fifty-four operations for a gastric adenocarcinoma were performed during 2004 which is almost two times the number performed during 2003. Laparoscopic radical procedures, such as a laparoscopy-assisted distal gastrectomy or total gastrectomy (LADG and LATG) have increased rapidly since 2001 (55 cases in 2001, 150 cases in 2002, 364 cases in 2003 and 738 cases in 2004). Especially, laparoscopic total gastrectomies were explosively adopted last year (20 cases in 2003 and 112 cases in 2004). However, laparoscopic function-preserving gastrectomies, which included one laparoscopy-assisted pylorus-preserving gastrectomy and laparoscopy-assisted proximal gastrectomy, are rarely performed at this time. One hundred forty-two wedge resections for a gastric submucosal tumor were performed during 2004. Hand-assisted laparoscopic surgery (HALS) was performed in 39 cases in 2001, 55 in 2002, and 49 in 2003; however, only 5 such surgeries were performed during 2004. In 2003, laparoscopic bariatric surgery began, and during 2004, 49 operations were performed. In terms of indications of laparoscopic gastric surgery for adenocarcinoma, 19 surgeons performed a LADG only for a T1 lesion, and 7 surgeons extended their indications to T2N0 lesions. In the near future, laparoscopic procedures for gastric cancer will be widely adopted in Korea if the medical-insurance obstacle is overcome, and the long-term survival results are verified.

• The Transactions of the Korea Information Processing Society
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• v.1 no.3
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• pp.367-379
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• 1994

This paper describes scheduling algorithms of the UNIX operating system and shows an analytical approach to approximate the average conditional response time for a process in the UNIX operating system. The average conditional response time is the average time between the submittal of a process requiring a certain amount of the CPU time and the completion of the process. The process scheduling algorithms in thr UNIX system are based on the priority service disciplines. That is, the behavior of a process is governed by the UNIX process schuduling algorithms that (ⅰ) the time-shared computer usage is obtained by allotting each request a quantum until it completes its required CPU time, (ⅱ) the nonpreemptive switching in system mode and the preemptive switching in user mode are applied to determine the quantum, (ⅲ) the first-come-first-serve discipline is applied within the same priority level, and (ⅳ) after completing an allotted quantum the process is placed at the end of either the runnable queue corresponding to its priority or the disk queue where it sleeps. These process scheduling algorithms create the round-robin effect in user mode. Using the round-robin effect and the preemptive switching, we approximate a process delay in user mode. Using the nonpreemptive switching, we approximate a process delay in system mode. We also consider a process delay due to the disk input and output operations. The average conditional response time is then obtained by approximating the total process delay. The results show an excellent response time for the processes requiring system time at the expense of the processes requiring user time.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.69-84
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• 1997

Background : Although the overall prognosis of patients with lung cancer is poor, highly effective treatment exists for the small subset of patients with early lung cancer(carcinoma in situ/micro- invasive cancer). But very few patients have benefit from them because these lesions are difficult to detect and localize with conventional white-light bronchoscopy. To overcome this problem, a Lung Imaging Fluorescence Endoscopic device(LIFE) was developed to detect and clearly delineate the exact location and extent of premalignant and early lung cancer lesions using differences in tissue autofluorescence. Purpose : The purpose of this study was to determine the difference of sensitivity and specificity in detecting dysplasia and carcinoma between fluorescence imaging and conventional white light bronchoscopy. Material and Methods : 35 patients (16 with abnormal chest X-ray, 2 with positive sputum study, 2 with undiagnosed pleural effusion, 15 with respiratory symptom) have been examined by LIFE imaging system. After a white light bronchoscopy, the patients were submitted to fluorescence bronchoscopy and the findings of both examinations have been classified in 3 categories(class I, II, III). From of all class n and III sites, 79 biopsy specimens have been collected for histologic examination: a comparison between histologic results and white light or fluorescence bronchoscopy has been performed for assessing sensitivity and specificity of the two methods. Results : 1) Total 79 sires in 35 patients were examined. Histology demonstrated 8 normal mucosa, 21 hyperplasia, 23 dysplasia, and 27 microinvasive and invasive carcinoma. 2) The sensitivity of white light or fluorescence bronchoscopy in detecting dysplasia was 60.9% and 82.6%, respectively. 3) The results of this study showed 70.3 % sensitivity for microinvasive or invasive carcinoma with LIFE system, versus 100% sensitivity for white light in 27 cases of carcinoma. The false negative study of LIFE system was 8 cases(3 adenocarcinoma and 5 small cell carcinoma), which were infiltrated in submucosal area and had normal epithelium. Conclusion : To improve the ability 10 diagnose and stage more accurately, fluorescence imaging may become an important adjunct to conventional bronchoscopic examination because of its high detection rate of premalignant and malignant epithelial lesion. But. it has limitation to detect in submucosal infiltrating carcinoma.