Long-Term Outcome of Definitive Radiotherapy for Early Glottic Cancer: Prognostic Factors and Patterns of Local Failure / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: This study evaluates the long-term results of definitive radiotherapy (RT) for early glottic cancer. Clinical and treatment factors related to local control and patterns of failure are analyzed. MATERIALS AND METHODS: We retrospectively reviewed 222 patients with T1-2N0 squamous cell carcinoma of the glottic larynx treated with definitive RT from 1981 to 2010. None of the patients received elective nodal RT or combined chemotherapy. The median total RT dose was 66 Gy. The daily fraction size was < 2.5 Gy in 69% and 2.5 Gy in 31% of patients. The RT field extended from the hyoid bone to the cricoid cartilage. RESULTS: The median age was 60 years, and 155 patients (70%) had T1 disease. The 5-year rates of local recurrence-free survival (LRFS) and ultimate LRFS with voice preservation were 87.8% and 90.3%, respectively. T2 (hazard ratio [HR], 2.30; 95% confidence interval [CI], 1.08 to 4.94) and anterior commissural involvement (HR, 3.37; 95% CI, 1.62 to 7.02) were significant prognostic factors for LRFS. In 34 patients with local recurrence, tumors recurred in the ipsilateral vocal cord in 28 patients. There were no contralateral vocal cord recurrences. Most acute complications included grade 1-2 dysphagia and/or hoarseness. There was no grade 3 or greater chronic toxicity. CONCLUSION: Definitive RT achieved a high cure rate, voice preservation, and tolerable toxicity in early glottic cancer. T2 stage and anterior commissural involvement were prognostic factors for local control. Further optimization of the RT method is needed to reduce the risk of ipsilateral tumor recurrence.

Hypofractionated three-dimensional conformal radiotherapy for medically inoperable early stage non-small-cell lung cancer

PURPOSE: The purpose of this study was to assess the clinical outcomes of hypofractionated radiotherapy (HFRT) with three-dimensional conformal technique for medically inoperable patients with early stage non-small-cell lung cancer (NSCLC) and to evaluate prognostic factors. MATERIALS AND METHODS: We performed a retrospective review of 26 patients who underwent HFRT for early stage NSCLC between September 2005 and August 2011. Only clinical stage T1-3N0 was included. The median RT dose was 70 Gy (range, 60 to 72 Gy) and the median biologically equivalent dose (BED) was 94.5 Gy (range, 78.0 to 100.8 Gy). In 84.6% of patients, 4 Gy per fraction was used. Neoadjuvant chemotherapy with paclitaxel and cisplatin was given to 2 of 26 patients. RESULTS: The median follow-up time for surviving patients was 21 months (range, 13 to 49 months). The overall response rate was 53.9%, and the initial local control rate was 100%. The median survival duration was 27.8 months. Rates of 2-year overall survival, progression-free survival (PFS), local control (LC), and locoregional-free survival (LRFS) were 54.3%, 61.1%, 74.6%, and 61.9%, respectively. Multivariate analysis showed that BED (>90 vs. < or =90 Gy) was an independent prognostic factor influencing PFS, LC, and LRFS. Severe toxicities over grade 3 were not observed. CONCLUSION: Radical HFRT can yield satisfactory disease control with acceptable rates of toxicities in medically inoperable patients with early stage NSCLC. HFRT is a viable alternative for clinics and patients ineligible for stereotactic ablative radiotherapy. BED over 90 Gy and 4 Gy per fraction might be appropriate for HFRT.

Role of Postoperative Radiotherapy for Microscopic Margin Involvement in the Squamous Cell Carcinoma of Esophagus / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The objective of this study was to assess the effect of postoperative radiotherapy on the outcome of esophageal cancer with microscopically positive resection margin by comparing the results with those of patients with negative resection margin. MATERIALS AND METHODS: Medical records of 88 patients treated with macroscopic resection followed by postoperative radiotherapy for stage II or III squamous cell carcinoma of the esophagus from June 1984 to March 2008 were reviewed. Twelve patients had received chemotherapy. Patients were classified into two groups based on resection margin status: negative resection margin (group A, n=66) and microscopically positive resection margin (group B, n=22). Median follow-up duration of living patients was 68 months (range, 18 to 115 months). Median total radiation dose of group A and group B was 51.5 Gy (range, 45 to 69 Gy) and 52.1 Gy (range, 45 to 64 Gy), respectively. RESULTS: Median overall survival and disease-free survival were 15 and 10 months, respectively. The five-year overall survival, disease-free survival, and local control rates for group A and group B were 15.9% and 16.4%, 13.5% and 9.1%, and 76.3% and 69.6%, respectively. No statistically significant difference in terms of overall survival, disease-free survival, and local control (p=0.295, p=0.209, and p=0.731, respectively) was observed between group A and group B. Seven patients experienced toxicity of grade 3 or higher. CONCLUSION: A significant portion of patients with margin involvement reached long term survival after addition of postoperative radiotherapy. These results suggest a potential role of postoperative radiotherapy, especially for patients with margin involvement.

Definitive Radiotherapy versus Postoperative Radiotherapy for Tonsil Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The purpose of this study is to analyze treatment outcome of radiotherapy (RT) in patients with stage III-IV tonsil cancer managed by surgery followed by postoperative RT (SRT) and definitive chemoradiotherapy (CRT), and to thereby evaluate the most feasible treatment modality. MATERIALS AND METHODS: Of 124 patients, 67 underwent CRT, and 57 underwent SRT. We compared survival and complication rates in both groups. RESULTS: The median follow-up time was 57 months (range, 19 to 255 months) for surviving patients. At five years, locoregional progression-free survival (LRPFS) and overall survival (OS) were 88% and 80%, respectively. No significant difference in LRPFS (p=0.491) and OS (p=0.177) was observed between CRT and SRT. In multivariate analysis, old age and higher T stage showed a significant association with poor LRPFS, PFS, and OS; higher N stage showed an association with poor PFS and a trend of poor LRPFS, while no association with OS was observed; treatment modality (CRT and SRT) showed no association with LRFPS, PFS, and OS. Grade 3 or higher mucositis was observed in 12 patients (21%) in the SRT group, and 25 patients (37%) in the CRT group. CONCLUSION: Definitive CRT and SRT have similar treatment outcomes for patients with stage III-IV tonsil cancer. Although acute complication rate appears to be higher in the CRT group, it should be noted that not all data on complications were included in this retrospective study. To determine the most feasible treatment modality, not only mucositis and xerostomia, but also emotional aspect and quality of life, should be considered.

Role of Radiotherapy for Squamous Cell Carcinoma of the External Auditory Canal and Middle Ear / 대한방사선종양학회지

PURPOSE: To investigate the role of radiotherapy for squamous cell carcinomas of the external auditory canal and middle ear. MATERIALS AND METHODS: A series of 35 patients who were treated at a single institution from 1981 through 2007 were retrospectively analyzed. Thirteen patients were treated by radiotherapy alone; four by surgery only and 18 by a combination of surgery and radiotherapy. The total radiation dose ranged from 39~70 Gy (median, 66 Gy) in 13~35 fractions for radiotherapy alone and 44~70 Gy (median, 61.2 Gy) in 22~37 fractions for the combined therapy. Clinical end-points were the cause of specific survival (CSS) and local relapse-free survival (LRFS). The median follow-up time was 2.8 years (range, 0.2~14.6 years). RESULTS: The 3-year CSS and LRFS rate was 80% and 63%, respectively. Based on a univariate analysis, performance status and residual disease after treatment had a significant impact on CSS; performance status and histologic grade for LRFS. Patients treated by radiotherapy alone had more residual disease following the course of treatment compared to patients treated with the combined therapy; 69% vs. 28%, respectively. CONCLUSION: Our results suggest that radiation alone was not an inferior treatment modality for CSS compared to the combined therapy for squamous cell carcinoma of the external auditory canal and middle ear. However, local failure after radiotherapy is the main issue that will require further improvement to gain optimal local control.

Management of Regional Lymph Nodes in Localized Vulvar Carcinoma / 대한방사선종양학회지

PURPOSE: To evaluate the impact of postoperative radiotherapy on loco-regional failure in patients with vulvar carcinoma and to determine the treatment strategy for inguinal lymph nodes. MATERIALS AND METHODS: Sixty-six patients who received treatment for primary vulvar carcinoma at Seoul National University Hospital, from October 1979 through June 2004, were retrospectively analyzed. Sixteen patients were excluded from the analysis due to the following reasons: distant metastases in two patients; palliative intent for six patients; previous radiotherapy given to the pelvis in three patients; follow-up loss after surgery for four patient; insufficient medical records for one patient. Of 50 eligible patients, 35 were treated with surgery alone (S), ten were treated with surgery followed by radiotherapy (S+RT), and five were treated with radiotherapy alone. RESULTS: The 5-year overall survival (OS) and disease-free survival (DFS) rates of all patients were 91% and 78%, respectively. Twelve patients (26%) experienced treatment failures and the sites of initial failure were as follows: a primary site in eight patients; regional lymph nodes in three patients; the lung in one patient. Although risk factors for failure were more common in the S+RT group than the S group of patients (p<0.05), the DFS rates were similar for the two groups (5-year DFS rates, 78% vs. 83%, p=0.66). The incidences of occult lymph node metastases was 10%. Ten of 31 patients with clinically negative lymph nodes did not received inguinal lymph node dissection, but no patient experienced regional failure. CONCLUSION: Postoperative radiotherapy may have a potential benefit for patients with risk factors for failure. The omission of inguinal dissection or elective radiotherapy to the inguinal lymph nodes may be considered in low-risk patients with clinically negative lymph nodes.

Postoperative External Beam Radiotherapy for Retroperitoneal Soft Tissue Sarcoma / 대한방사선종양학회지

PURPOSE: To evaluate the clinical outcomes and prognostic factors in retroperitoneal soft tissue sarcomas treated by postoperative radiotherapy. MATERIALS AND METHODS: The records of 23 patients with retroperitoneal soft tissue sarcomas, who underwent postoperative radiotherapy between 1985 and 2003, were analyzed. The median follow-up period was 77 months (range, 8~240 months). A total of 21 patients presented with primary disease, and two patients presented with recurrent disease. Liposarcomas and leiomyosarcomas represented 78% of the diagnosed tumor cases. Moreover, 17 cases were of high grade (grade 2 or 3). The median tumor size was 13 cm (range, 3~50 cm). Complete excision was achieved in 65% of patients. The median radiation dose was 50.4 Gy (range, 45.0 to 59.4 Gy), with conventional fractionation. RESULTS: The 5-year overall, local recurrence-free, and distant metastasis-free survival rates were 68%, 58%, and 71%, respectively. Eleven patients experienced local recurrence, while 9 patients experienced distant metastasis. The most common site for distant metastasis was the liver. A univariate analysis revealed that adjacent organ invasion and age (> 60 years) as the significant risk factors contributing to the prediction of poor overall survival. Moreover, multivariate analyses indicated that adjacent organ invasion remained significantly associated with a higher risk of death. In addition, patient age (> 60 years) was the other identified risk factor for local recurrence by univariate and multivariate analyses. Except for one case of grade 3 diarrhea, no patient suffered grade 3 or higher complications. CONCLUSION: Our results were comparable to previous reports in that adjacent organ invasion and patient age (> 60 years) were significant predictors of poor survival and tumor recurrence, respectively.

The Necessity of Early Adjuvant Radiotherapy for Better Outcomes in the Treatment of a Desmoid Tumor / 대한방사선종양학회지

PURPOSE: This retrospective study was conducted to assess outcome and to determine the prognostic factors in patients with a desmoid tumor treated with postoperative radiotherapy. MATERIALS AND METHODS: Twenty-seven patients with a desmoid tumor who were treated with postoperative radiotherapy between June 1984 and October 2005 were analyzed. There were 13 male and 14 female patients. The age of the patients ranged from 3 to 79 years (median age, 28 years). Tumors were located in an extra-abdominal area (21 cases), and in the abdominal walls (6 cases). The tumor size ranged from 2.5 to 25 cm (median size, 7.5 cm) in the largest linear dimension. Thirteen cases received radiotherapy after initial surgery, and 14 recurrent cases received radiotherapy after additional surgery. The total radiation dose given was 45~66 Gy (median dose, 59.4 Gy), and the fraction size was 1.8~2.0 Gy. RESULTS: The median follow-up period was 61 months (range, 12~203 months). Two patients developed local progression and six patients experienced local recurrence. The 5-year disease-free survival rate and the 5-year progression-free survival rate were 61% and 70%, respectively. Wide local excision was associated with better disease free survival with statistical significance (p=0.028). Radiotherapy after initial surgery (p=0.046) and a higher radiation dose of more than 60 Gy (p=0.049) were associated with better progression free survival with statistical significance. At the time of the last follow-up, the number of additional surgeries was higher in patients that received radiotherapy after reoperation (p<0.001). CONCLUSION: Radiotherapy after the initial operation improved local control and decreased the number of subsequent operations. Thus, postoperative radiotherapy after an initial operation is recommended in patients with a high risk of recurrence for a desmoid tumor.

A Comparison of Peripheral Doses Scattered from a Physical Wedge and an Enhanced Dynamic Wedge / 의학물리

In order to evaluate the radio-protective advantage of an enhanced dynamic wedge (EDW) over a physical wedge (PW), we measured peripheral doses scattered from both types of wedges using a 2D array of ion-chambers. A 2D array of ion-chambers was used for this purpose. In order to confirm the accuracy of the device, we first compared measured profiles of open fields with the profiles calculated by our commissioned treatment planning system. Then, we measured peripheral doses for the wedge angles of 15 degrees, 30 degrees, 45 degrees, and 60 degrees at source to surface distances (SSD) of 80 cm and 90 cm. The measured points were located at 0.5 cm depth from 1 cm to 5 cm outside of the field edge. In addition, the measurements were repeated by using thermoluminescence dosimeters (TLD). The peripheral doses of EDW were (1.4% to 11.9%) lower than those of PW (2.5% to 12.4%). At 15 MV energy, the average peripheral doses of both wedges were 2.9% higher than those at 6MV energy. At a small SSD (80 cm vs. 90 cm), peripheral dose differences were more recognizable. The average peripheral doses to the heel direction were 0.9% lower than those to the toe direction. The results from the TLD measurements confirmed these findings with similar tendency. Dynamic wedges can reduce unnecessary scattered doses to normal tissues outside of the field edge in many clinical situations. Such an advantage is more profound in the treatment of steeper wedge angles, and shorter SSD.

Development of Immobilization Devices for Patients with Pelvic Malignancies and a Feasibility Evaluation during Radiotherapy / 대한방사선종양학회지

PURPOSE: Immobilization devices that improve the setup reproducibility of pelvic cancer patients and that provide comfort to patients during radiotherapy were designed and the feasibility of the devices was evaluated. MATERIALS AND METHODS: A customized device was designed to immobilize a knee, thigh, and foot of a patient. Sixty-one patients with prostate cancer were selected and were divided into two groups-with or without devices. The setup errors were measured with respect to bony landmarks. The difference between digitally reconstructed radiographs (DRR) and simulation films, and the differences between DRR and portal films were measured. RESULTS: The left-right (LR), anterior-posterior (AP) and craniocaudal (CC) errors between the DRR and simulation films were 1.5+/-0.9 mm, 3.0+/-3.6 mm, and 1.6+/-0.9 mm, respectively without devices. The errors were reduced to 1.3+/-1.9 mm, 1.8+/-1.5 mm and 1.1+/-1.1 mm, respectively with the devices. The errors between DRR and portal films were 1.6+/-1.2 mm, 4.0+/-4.1 mm, and 4.2+/-5.5 mm, respectively without the devices and were reduced to 1.0+/-1.8 mm, 1.2+/-0.9 mm, and 1.2+/-0.8 mm, respectively, with the devices. The standard deviations among the portal films were 1.1 mm, 2.1 mm, and 1.0 mm at each axis without the devices and 0.9 mm, 1.6 mm and 0.8 mm with the devices. The percentage of setup errors larger than 3 mm and 5 mm were significantly reduced by use of the immobilization devices. CONCLUSION: The designed devices improved the setup reproducibility for all three directions and significantly reduced critical setup errors.

Assessment of Respiratory Tumor Movement using 4D Computed Tomography for Stereotactic Radiosurgery in Lung Tumor

PURPOSE : To assess the respiratory tumor movement using 4D-CT (4-dimensional computed tomography) for minimizing setup and target volume uncertainty of body-frame based stereotactic radiosurgery (SRS) in lung tumor. MATERIALS AND METHODS : Fifty-seven stereotactic radiation therapies with respiratory gating system in 44 patients (two targets in seven patients and three in three patients) were executed in Asan Medical Center from May 2005 to June 2006. We used respiratory gating system consisted of RPM (Real-time Positioning Management system, Varian, USA) and 4D-CT (GE healthcare, USA), if tumor movement was exceeding 5 mm by respiration on fluoroscopy. Accurate tumor movement on reconstructed 4D-CT image was determined for respiratory gated therapy. Respiratory gated therapy was done if tumor movement was exceeding 5 mm, and non-gated therapy was done if it was below 5 mm. RESULTS : Forty-five tumors were treated with supine position, and the other twelve were with prone position. Median tumor movement (3-dimensional) by respiration was 8.78+/-5.30 mm, and it was mostly affected by superior-inferior movement (8.53+/-5.23 mm). Tumor movements were different by tumor location, whether upper (5.38+/-2.85 mm) or lower (10.12+/-5.08 mm) lobe (p=0.015). Tumor movement was exceeding 5 mm in 27 (47.3%) tumors, and below 5 mm in 30 tumors in 4D-CT evaluation. Tumor movements on adopted respiratory gated phase were wholly below 5 mm, and its median value was 3.70+/-1.13 mm. CONCLUSION : Assessment of respiratory tumor movement using 4D-CT and gating system was helpful for minimizing target volume uncertainty. As a result, image-guided radiation therapy could improve the treatment accuracy of high precision stereotactic radiosurgery

Retrospective Analysis of the Treatment Results for Patients with Squamous Cell Carcinoma of Tonsil / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: There has been no definitive randomized study to identify the optimal therapeutic regimen for treating squamous cell carcinoma of tonsil. The purpose of this study was to retrospectively evaluate the treatment outcome according to various combinations of surgery, radiation therapy and chemotherapy. MATERIALS AND METHODS: Fifty-six patients with tonsillar carcinoma, who were treated at Seoul National University Hospital from March 1985 to August 2001, were the subjects of this study. Twenty-one patients received surgery followed by radiation therapy (SRT), 16 patients underwent radiation therapy alone (RT), and 19 patients received neoadjuvant chemotherapy and radiation therapy (CRT). The median radiation dose was 66.6 Gy for the SRT group and 70.2 Gy for the RT and CRT groups. Surgery comprised extended tonsillectomy and modified radical neck dissection of the involved neck. Cisplatin and 5-fluorouracil were used every three weeks for 3 cycles in the SRT group. The median follow-up was 73.2 months. RESULTS: The distribution of T-stage was 4 cases of T1, 14 cases of T2, 1 case of T3 and 2 cases of T4 staging in the SRT group, 2 cases of T1, 6 cases of T2, 5 cases of T3 and 3 cases of T4 staging in the RT group and 0 cases of T1, 7 cases of T2, 9 cases of T3 and 3 cases of T4 staging in the CRT group. The distribution of N-stage was 5 cases of N0, 2 cases of N1, 13 cases of N2 and 1 case of N3 staging in the SRT group, 6 cases of N0, 5 cases of N1, 5 cases of N2 and 0 cases of N3 staging in the RT group, and 2 cases of N0, and 7 cases of N1, 9 cases of N2 and 1 case of N3 staging in the CRT group. The five-year overall survival rate (OSR) for all patients was 78%. The five-year OSR was 80% for the SRT group, 71% for the RT group, and 80% for the CRT group (p=ns). The five-year disease-free survival rate was 93% for the CRT group and 71% for the RT group (p=0.017). Four patients developed local failure and one patient failed at a regional site in the RT group, and one patient failed at a primary site in the CRT group. The five-year DFS was 84% for patients who had undergone neck dissection and 76% for patients who had not undergone neck dissection (p=ns). Treatment-related complications of grade 3 or 4 occurred in 15 patients, and the incidence of complication was not different between each of the treatment methods. CONCLUSION: Although the patients with more advanced T stage were included in the RT and CRT groups, the OSR was not statistically different according to the treatment methods. In the radical radiation therapy group, the addition of neoadjuvant chemotherapy showed an improvement in the disease-free survival. Because of the retrospective nature of our study and the small number of patients, this study cannot draw any definite conclusions, but it suggests that radiation therapy with chemotherapy can be a good alternative option for squamous cell carcinoma of tonsil. Controlled randomized study is necessary to confirm this hypothesis.

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.

Postoperative Radiotherapy for Parotid Gland Malignancy / 대한방사선종양학회지

PURPOSE: The aim of this study was to evaluate the clinical results of postoperative radiotherapy for parotid gland malignancy, and determine prognostic factors for locoregional control and survival. MATERIALS AND METHODS: Between 1980 and 2002, 130 patients with parotid malignancy were registered in the database of the Department of Radiation Oncology, Seoul National University Hospital. The subjects of this analysis were the 72 of these 130 patients who underwent postoperative irradiation. There were 42 males and 30 females, with a median age of 46.5 years. The most common histological type was a mucoepidermoid carcinoma. There were 6, 23, 23 and 20 patients in Stages I, II, III and IV, respectively. The median dose to the tumor bed was 60 Gy, with a median fraction size of 1.8 Gy. RESULTS: The overall 5 and 10 year survival rates were 85 and 76%, respectively. The five-year locoregional control rate was 85%, which reached a plateau phase after 6 years. Sex and histological type were found to be statistically significant for overall survival from a multivariate analysis. No other factors, including age, facial nerve palsy and stage, were related to overall survival. For locoregional control, nodal involvement and positive resection margin were associated with poor local control. Histological type, tumor size, perineural invasion and type of surgery were not significant for locoregional control. CONCLUSION: A high survival rate of parotid gland malignancies, with surgery and postoperative radiotherapy, was confirmed. Sex and histological type were significant prognostic factors for overall survival. Nodal involvement and a positive resection margin were associated with poor locoregional control.

Treatment Outcome of Metastatic Carcinoma of Cervical Lymph Node from an Unknown Primary / 대한방사선종양학회지

PURPOSE: To analyze the outcome of radiation therapy for patients with a metastatic carcinoma of cervical lymph nodes from an unknown primary (MUO), and identify the prognostic factors for these patients. MATERIALS AND METHODS: Between July 1981 and June 1999, 39 patients with MUO underwent radiation therapy with curative intent. Twelve patients were treated with radiation therapy alone (Group 1), 8 with neoadjuvant chemotherapy followed by radiation therapy (Group 2), and 19 with either an excision or neck dissection and postoperative radiation therapy (Group 3). There were 31 males and 8 females, with a median age of 55 years, ranging from 25 to 77 ears. The median duration of follow-up was 38 months, ranging from 3 to 249 months. RESULTS: The 5-year overall survival rate was 55%. According to the treatment modality, the 5-year disease-free survival rates of Groups 1, 2 and 3 were 48, 19 and 75%, respectively (p=0.0324). In addition to the treatment modality, the appearance of the primary site was a significant prognostic factor for disease-free survival (p=0.0085). CONCLUSION: Surgical resection and radiation therapy achieves a superior disease-free survival compared to radiation therapy alone, either with or without chemotherapy. Further investigation is needed to evaluate the role of chemotherapy in the treatment of MUO.

Postoperative Radiotherapy for Parotid Gland Malignancy / 대한방사선종양학회지

PURPOSE: The aim of this study was to evaluate the clinical results of postoperative radiotherapy for parotid gland malignancy, and determine prognostic factors for locoregional control and survival. MATERIALS AND METHODS: Between 1980 and 2002, 130 patients with parotid malignancy were registered in the database of the Department of Radiation Oncology, Seoul National University Hospital. The subjects of this analysis were the 72 of these 130 patients who underwent postoperative irradiation. There were 42 males and 30 females, with a median age of 46.5 years. The most common histological type was a mucoepidermoid carcinoma. There were 6, 23, 23 and 20 patients in Stages I, II, III and IV, respectively. The median dose to the tumor bed was 60 Gy, with a median fraction size of 1.8 Gy. RESULTS: The overall 5 and 10 year survival rates were 85 and 76%, respectively. The five-year locoregional control rate was 85%, which reached a plateau phase after 6 years. Sex and histological type were found to be statistically significant for overall survival from a multivariate analysis. No other factors, including age, facial nerve palsy and stage, were related to overall survival. For locoregional control, nodal involvement and positive resection margin were associated with poor local control. Histological type, tumor size, perineural invasion and type of surgery were not significant for locoregional control. CONCLUSION: A high survival rate of parotid gland malignancies, with surgery and postoperative radiotherapy, was confirmed. Sex and histological type were significant prognostic factors for overall survival. Nodal involvement and a positive resection margin were associated with poor locoregional control.

Treatment Outcome of Metastatic Carcinoma of Cervical Lymph Node from an Unknown Primary / 대한방사선종양학회지

PURPOSE: To analyze the outcome of radiation therapy for patients with a metastatic carcinoma of cervical lymph nodes from an unknown primary (MUO), and identify the prognostic factors for these patients. MATERIALS AND METHODS: Between July 1981 and June 1999, 39 patients with MUO underwent radiation therapy with curative intent. Twelve patients were treated with radiation therapy alone (Group 1), 8 with neoadjuvant chemotherapy followed by radiation therapy (Group 2), and 19 with either an excision or neck dissection and postoperative radiation therapy (Group 3). There were 31 males and 8 females, with a median age of 55 years, ranging from 25 to 77 ears. The median duration of follow-up was 38 months, ranging from 3 to 249 months. RESULTS: The 5-year overall survival rate was 55%. According to the treatment modality, the 5-year disease-free survival rates of Groups 1, 2 and 3 were 48, 19 and 75%, respectively (p=0.0324). In addition to the treatment modality, the appearance of the primary site was a significant prognostic factor for disease-free survival (p=0.0085). CONCLUSION: Surgical resection and radiation therapy achieves a superior disease-free survival compared to radiation therapy alone, either with or without chemotherapy. Further investigation is needed to evaluate the role of chemotherapy in the treatment of MUO.

Patient Specific Quality Assurance of IMRT: Quantitative Approach Using Film Dosimetry and Optimization / 대한방사선종양학회지

PURPOSE: Film dosimetry as a part of patient specific intensity modulated radiation therapy quality assurance (IMRT QA) was performed to develop a new optimization method of film isocenter offset and to then suggest new quantitative criteria for film dosimetry. MATERIALS AND METHODS: Film dosimetry was performed on 14 IMRT patients with head and neck cancers. An optimization method for obtaining the local minimum was developed to adjust for the error in the film isocenter offset, which is the largest part of the systemic errors. RESULTS: The adjust value of the film isocenter offset under optimization was 1 mm in 12 patients, while only two patients showed 2 mm translation. The means of absolute average dose difference before and after optimization were 2.36 and 1.56%, respectively, and the mean ratios over a 5% tolerance were 9.67 and 2.88%. After optimization, the differences in the dose decreased dramatically. A low dose range cutoff (L-Cutoff) has been suggested for clinical application. New quantitative criteria of a ratio of over a 5%, but less than 10% tolerance, and for an absolute average dose difference less than 3% have been suggested for the verification of film dosimetry. CONCLUSION: The new optimization method was effective in adjusting for the film dosimetry error, and the newly quantitative criteria suggested in this research are believed to be sufficiently accurate and clinically useful.

Patient Specific Quality Assurance of IMRT: Quantitative Approach Using Film Dosimetry and Optimization / 대한방사선종양학회지

PURPOSE: Film dosimetry as a part of patient specific intensity modulated radiation therapy quality assurance (IMRT QA) was performed to develop a new optimization method of film isocenter offset and to then suggest new quantitative criteria for film dosimetry. MATERIALS AND METHODS: Film dosimetry was performed on 14 IMRT patients with head and neck cancers. An optimization method for obtaining the local minimum was developed to adjust for the error in the film isocenter offset, which is the largest part of the systemic errors. RESULTS: The adjust value of the film isocenter offset under optimization was 1 mm in 12 patients, while only two patients showed 2 mm translation. The means of absolute average dose difference before and after optimization were 2.36 and 1.56%, respectively, and the mean ratios over a 5% tolerance were 9.67 and 2.88%. After optimization, the differences in the dose decreased dramatically. A low dose range cutoff (L-Cutoff) has been suggested for clinical application. New quantitative criteria of a ratio of over a 5%, but less than 10% tolerance, and for an absolute average dose difference less than 3% have been suggested for the verification of film dosimetry. CONCLUSION: The new optimization method was effective in adjusting for the film dosimetry error, and the newly quantitative criteria suggested in this research are believed to be sufficiently accurate and clinically useful.

Polymorphisms of DNA Repair Gene XRCC1 and Radiation Sensitivity

PURPOSE: The goal of this study was to find lung cancer-related single nucleotide polymorphisms (SNP) and define their association with clinical results. Material and Methods: One hundred and thirty-six non-small cell lung cancer patients, who received radiotherapy at the Asan Medical Center, were recruited between August 2002 and September 2003. Demographic and clinical informations were obtained from a self-administered questionnaire and from the subject's medical records, respectively. Blood samples were collected from all study subjects at the time of enrollment. Genomic DNA was extracted from peripheral blood lymphocytes using a QIAamp DNA Blood Mini Kit. TaqMan assay, denaturing HPLC and single base pair primer extension assay using SNaPshot kits were employed as the SNP screening techniques. The candidate SNP for screening was XRCC1-R399Q. RESULTS: Patients carrying the 399Gln variant allele had a significantly longer progression-free survival than those with the 399Arg homozygote in tumor stages I-IIIa (p=0.005). In the Cox-proportional hazards model, the XRCC1 codon 399 polymorphism was a statistically significant predictor for progression-free survival in tumor stages I-IIIa (p=0.03). CONCLUSION: The use of molecular predictors of the progression-free survival in non-small cell lung cancer patients, particularly at stages I-IIIa, may provide important criteria for prognosis of the patients undergoing radiotherapy. However, there is still a need for further study to establish the role of these polymorphisms as useful predictors