[en] Nuclear ship reactors have several; features different from land-based PWR's. Especially, effects of ship motions on reactor thermal-hydraulics and good load following capability for abrupt load changes are essential characteristics of nuclear ship reactors. This study modified the RETRAN-03 to analyze the thermal-hydraulic transients under three-dimensional ship motions, named RETRAN-03/MOV in order to apply to future marine reactors. First Japanese nuclear ship MUTSU reactor have been analyzed under various ship motions to verify this code. Calculations have been performed under rolling,heaving and stationary inclination conditions during normal operation. Also, the natural circulation has been analyzed, which can provide the decay heat removed to ensure the passive safety of marine reactors. As results, typical thermal-hydraulic characteristics of marine reactors such as flow rate oscillations and S/G water level oscillations have been successfully simulated at various conditions. 7 refs., 11 figs. (author)

[en] Purpose: The cyclooxygenase (COX)-2 enzyme has been shown to have an important role in carcinogenesis and apoptosis in various types of cancer. The purpose of this study was to evaluate the relationship between local recurrence or distant metastasis and COX-2 expression and apoptosis in cervical cancer patients treated with radical radiotherapy (RT). Methods and Materials: Twenty-two patients who were diagnosed with cervical cancer were enrolled in this study. All patients were treated with radical RT (external beam RT plus brachytherapy) at Seoul National University Hospital. The formalin-fixed, paraffin-embedded tissues of 11 patients who developed local recurrence (n=3) or distant metastasis (n=8) were compared with those of other patients who were disease free. Prognostic factors, including tumor size, lymph node metastatic status, and stage, were well balanced between the two groups. COX-2 expression was determined immunohistochemically, and apoptosis was assessed using in situ DNA nick end labeling (TUNEL)-based methods. Results: COX-2 expression was stronger in the local recurrence and distant metastasis patients than in those free of disease. COX-2 expression was shown to have a statistically significant influence on treatment failure by the Mann-Whitney U test (p=0.015) and the Mantel-Haenszel chi-square test (p=0.015), but its distribution did not correlate with apoptosis. Among the clinicopathologic factors, including stage, lymph node metastatic status, and tumor size, lymph node metastatic status was found to closely correlate with COX-2 expression by the Mann-Whitney U test (p=0.045) and Mantel-Haenszel chi-square test (p=0.065). Conclusion: COX-2 is believed to be one of the important factors associated with lymph node involvement and treatment failure. Our results suggest that inhibiting COX-2 may decrease treatment failure in cervical cancer treated with RT, and that COX-2 inhibitor administration may play an adjuvant role in cervical cancer treatment

[en] We attempted to analyze the effectiveness of whole brain radiotherapy (WBRT) combined with fractionated stereotactic radiotherapy (FSRT) in brain metastases. Thirty-seven metastatic brain tumors in 29 patients without previous treatment were treated with WBRT plus FSRT, from October 1996 to February 2002. Four of the patients received stereotactic radiosurgery (SRS) prior to WBRT. Non-small cell lung cancer was the most common type of primary tumor (20/29). The total dose to the whole brain ranged from 30 Gy to 40 Gy, and the boost dose from FSRT ranged from 12 Gy to 40 Gy. End points were survival rate and local control rates. Factors influencing survival were evaluated. Median survival was 13 months, and actuarial survival rates at one and two years were 81% and 39%, respectively. Actuarial one and two year local control rates for all lesions were 78% and 71%, respectively. Survival was significantly associated with age, tumor size, presence of active extracranial tumors, and performance status. No acute or delayed complications were observed. We believe that WBRT plus FSRT should be included in the treatment options for metastatic brain tumors, and we consider the effect of this non-invasive method to be quite good in patients with good prognostic factors, although other invasive modalities could also be effective in them. (author)

[en] A new fiduciary plate and orientation marker have been devised to assist the quality assurance (QA) procedures for port films in radiation therapy department. The plate is used in conjunction with the film/cassette combination during weekly QA procedures, at Seoul National University Hospital (SNUH), in order to verify treatment fields in high energy radiation therapy. A new fiduciary plate was fabricated using an acrylic plate, cerrobend, standard blocking tray and mercury. The acrylic plate had the dimension of 1 x 25 x 25 cm, with two fiduciary markers. The plate was rigidly attached onto the standard blocking tray, thus making it easier to set the fiduciary plate to the center of the radiation field of the linear accelerator. The plate had two 2-mm vertical and horizontal lines, with the minor scales in 2-cm steps. The orientation marker was a small mercury filled disk, which was inserted into the plate. The geometrical structure of the lines in the plate makes it easier to correlate two different images between the simulation and port films. The marker clearly indicated the orientation of the film, for example, the anterior, posterior, left, right and various oblique orientations, without the placement of a conventional orientation marker. Also, the new orientation marker could easily be applled to the simulator by placing the small orientation marker onto the image intensifier or in front of the film/cassette holder. The new fiduciary plate appears to be useful in verifying the treatment fields, and the new orientation marker makes the film orientation simple, which is expected to lower the block fabrication errors

[en] To determine whether the maximum standardized uptake value (SUV) of [18F] fluorodeoxyglucose uptake by positron emission tomography (FDG PET) ratio of lymph node to primary tumor (mSUVR) could be a prognostic factor for node positive non-small cell lung cancer (NSCLC) patients treated with definitive radiotherapy (RT). A total of 68 NSCLC T1-4, N1-3, M0 patients underwent FDG PET before RT. Optimal cutoff values of mSUVR were chosen based on overall survival (OS). Independent prognosticators were identified by Cox regression analysis. The most significant cutoff value for mSUVR was 0.9 with respect to OS. Two-year OS was 17% for patients with mSUVR > 0.9 and 49% for those with mSUVR ≤ 0.9 (p = 0.01). In a multivariate analysis, including age, performance status, stage, use of chemotherapy, and mSUVR, only performance status (p = 0.05) and mSUVR > 0.9 (p = 0.05) were significant predictors of OS. Two-year OS for patients with both good performance (Eastern Cooperative Oncology Group [ECOG] ≤ 1) and mSUVR ≤ 0.9 was significantly better than that for patients with either poor performance (ECOG > 1) or mSUVR > 0.9, 23% (71% vs. 23%, p = 0.04). Our results suggested that the mSUVR was a strong prognostic factor among patients with lymph node positive NSCLC following RT. Addition of mSUVR to performance status identifies a subgroup at highest risk for death after RT.

[en] We intended to decrease late CNS reaction after radical radiotherapy for an intracranial germinoma by using combined neoadjuvant chemotherapy and involved-field radiotherapy. The efficacy in terms of its acute toxicity and short-term relapse patterns was analyzed. Eighteen patients were treated with combined neoadjuvant chemotherapy and radiotherapy between 1995 and 2001. The chemotherapy regimen used was the Children's Cancer Group (CCG) 9921A (cisplatin, cyclophosphamide, VP-16, vincristine) for 5 patients younger than 16 years, BEP(bleomycin, VP-16, cisplatin) for 12 patients, and EP (VP-16, cisplatin) for 1 patient. The radiotherapy covered the whole craniospinal axis for 5 patients, the whole brain for 1, and the partial brain (involved field) for 12. the primary lesion received tumour doses between 3,960 and 5,400 cGy. The male to female ratio was 16:2 and the median age was 16 years old. The tumors were located in the pineal gland in 12 patients, in the suprasellar region in 1, in the basal ganglia in 1, in the thalamus in 1. Three patients had multiple lesions and ventricular seedings were shown at MRI. In 3 patients, tumor cells were detected in the cerebrospinal fluid and MRI detected a spinal seeding in 2 patients. The response to neoadjuvant chemotherapy was complete remission in 5 patients, partial remission in 12, and no response in 1. However, after radiotherapy, all except 1 patient experienced complete remission. The toxicity during or after chemotherapy greater than or equal to grade III was remarkable; hematologic toxicity was observed in 11 patients, liver toxicity in none, kidney toxicity in none, and gastrointestinal toxicity in one. One patient suffered from bleomycin-induced pneumonitis. Radiotherapy was therefore stopped and the patient eventually died of respiratory failure. The other 17 are alive without any evidence of disease or relapse during an average of 20 months follow-up. A high response rate and disease control was experienced, which was the same as observed other studies and the morbidity from chemotherapy-induced toxicity was similar. With these results, the results from adjuvant chemotherapy and involved-field radiotherapy cannot be concluded to be equal to those from extended-field radiotherapy. The long term follow-up study on later complications are required in order to draw definite conclusions on the optimal management with minimum side effects

[en] Purpose : In this retrospective study, we attempted to evaluate the treatment outcome and the prognostic factors of thymoma treated with surgery, radiotherapy and chemotherapy. Methods and materials : Between 1979 and 1998, 55 patients with thymoma were treated at the Seoul National University Hospital. Of these, 11 patients underwent surgery only, 33 patients received postoperative radiotherapy and 11 patients received radiotherapy only. Twenty-three patients had gross total resection and 21 patients subtotal resection. For postoperative radiotherapy, the radiation dose consisted of 41.4∼55.8 Gy. The average follow-up was 64 months, and ranged from 2 to 160 months. The sex ratio was 1:1 and the median age was 48 years (15∼74 years). Overall survival and disease-free survival were determined via the Kaplan-Meier method, and the log-rank was employed to evaluate for differences in prognostic factor. Results : The five- and 10-year survival rates were 87% and 65% respectively, and the median survival was 103 months. By univariate analysis, only stage ( p=0.0017) turned out to be significant prognostic factors of overall survival. Also, stage ( p=0.0007) was significantly predictive for overall survival in mutivariated analysis. Conclusion : This study showed the stage was found to be important prognostic factors, which influenced survival. Especially, as incomplete resection is related with poor results, complete resection is important to cure the invasive thymoma

[en] Histone deacetylase inhibitors (HDIs) have attracted considerable attention for anticancer therapy strategy, including radiosensitization. Regarding a potential application of HDI as a radiosensitizer in the treatment of solid tumors, an important question is whether treatment efficacy would be influenced by intrinsic differences between cancer cells, such as different histologic origin and status of ataxia telangiectasia mutated (ATM) or p53. First we have observed the in vitro radiosensitization by Trichostatin A (TSA) on the broad spectrum of human tumor cell lines having different histologic origin such as HCT116 adenocarcinoma of colon, A549 adenocarcinoma of lung, HN-3 squamous cell carcinoma of head/neck, and HeLa squamous carcinoma of uterine cervix, using clonogenic assay. Next, we have systematically assessed the radiosensitization on the cell lines having different ATM or p53 status. We found that pretreatment of HDI consistently resulted in radiosensitization of all cell lines tested, though the sensitizer enhancement ratio of individual cell lines was variable. We also observed that TSA-mediated radiosensitization was clearly influenced by p53 and ATM status of cells tested. The data presented here indicate that HDI enhances the radiation induced cell killing in the various cancer cells having intrinsic differences and may serve as a general strategy for enhancing tumor cell radiosensitivity. These results have potential implications for the clinical utility of HDI in increasing the anticancer efficacy of radiation. (author)

[en] We evaluated treatment outcomes of thymic carcinomas to determine prognostic factors for survival. Between May 1988 and May 2009, 41 patients had pathologic diagnosis of thymic carcinoma in Seoul National University Hospital, Seoul, Korea. Of these, 40 patients were followed up to 188 months after treatment. The mean age of all patients was 58.3 years and male to female ratio was 23 to 17. Among 30 patients who underwent surgical resection, 26 achieved R0 resection and postoperative radiotherapy (PORT) was performed in 22 patients (73%). Various chemotherapeutic regimens were given with local treatment modalities, surgery and/or radiotherapy, in 12 patients. The 5-year locoregional control (LRC), distant metastasis-free survival, progression-free survival (PFS), and overall survival were 79.4%, 53.0%, 42.6%, and 63.6%, respectively. Patients with Masaoka stage I or II showed excellent prognosis of 5-year PFS around 90%. In advanced stages, invasion of the great vessels or atrium by thymic carcinomas was negative prognostic factor for PFS in univariate analysis. Lymph node involvement was statistically significant factor for LRC and PFS. Local or regional recurrence was infrequent after surgical resection followed by PORT, while distant metastasis was the major component of treatment failure. Complete resection followed by PORT provided remarkable local control without severe acute toxicities in patients with stage II and favorable stage III thymic carcinoma. Invasion of the great vessels or atrium was statistically significant prognostic factor for PFS.

[en] A widely-adopted patient-specific quality assurance (QA) method for volumetric modulated arc therapy (VMAT) is the use of gamma-index method suggested by Low et al. . The plans are evaluated according to gamma passing rates with certain criterion. Even though, the criterion of 2%/2 mm has been typically used for the gamma evaluation of the stereotactic body radiation therapy (SBRT) VMAT QA, it has not been investigated that the 2%/2 mm would be clinically relevant or not. In this study, we investigated clinical relevance of VMAT QA results for SBRT according to various gamma criteria by introducing intentional high-definition multi-leaf collimator (HD-MLC) misalignments in verification plans. The clinical relevance was evaluated by analyzing changes in the dose volume histograms (DVH) of each structure. Ten lung and 10 spine SBRT VMAT plans (20 plans total) were selected for this study. And then, statistical significances of the results were analyzed. The absolute gamma method with the criterion of 2%/1 mm was most suitable with a passing rate of 90% as a tolerance level for a patient-specific VMAT QA for SBRT