• Asian Pacific Journal of Cancer Prevention
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• 제16권8호
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• pp.3365-3370
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• 2015

Radiotherapy has an important role in the treatment of prostate cancer. Three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques are all applied for this purpose. However, the risk of secondary radiation-induced bladder cancer is significantly elevated in irradiated patients compared surgery-only or watchful waiting groups. There are also reports of risk of secondary cancer with low doses to normal tissues. This study was designed to compare received volumes of low doses among 3D-CRT, IMRT and VMAT techniques for prostate patients. Ten prostate cancer patients were selected retrospectively for this planning study. Treatment plans were generated using 3D-CRT, IMRT and VMAT techniques. Conformity index (CI), homogenity index (HI), receiving 5 Gy of the volume (V5%), receiving 2 Gy of the volume (V2%), receiving 1 Gy of the volume (V1%) and monitor units (MUs) were compared. This study confirms that VMAT has slightly better CI while thev olume of low doses was higher. VMAT had lower MUs than IMRT. 3D-CRT had the lowest MU, CI and HI. If target coverage and normal tissue sparing are comparable between different treatment techniques, the risk of second malignancy should be a important factor in the selection of treatment.

• 대한방사선치료학회지
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• 제20권2호
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• pp.115-122
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• 2008

목 적: 암 치료를 위한 방사선치료 기술은 끊임없이 발전되어 왔으며 특히, 컴퓨터와 전자기 공학의 발달과 더불어 급속하게 방사선 치료분야에서 많은 발전을 하게 되었다. 따라서 본 연구에서는 발전된 치료기술에 대한 치료 원리와 방법들을 중심으로 그 특징들을 고찰하려고 한다. 대상 및 방법: 발전된 치료기술에 관한 이론적인 고찰을 위하여 관련된 문헌조사를 실시하였으며 임상에서의 자료를 광범위하게 조사 연구하였다. 결 과: 방사선을 이용한 암에 대한 치료는 눈부신 발전을 거듭하고 있다. 과거에는 2차원적인 방법으로 방사선치료를 하였으나 현재는 3차원적인 입체조형치료, 세기변조방사선치료를 병행한 4차원적인 치료기술이 도입되었으며 이는 과거 방사선치료의 난제였던 정상조직보호와 방사선에 의한 합병증 해결을 가능하게 하였다. 결 론: 발전된 방사선치료인 3, 4차원적 현대적 치료는 방사선치료의 목적에 부합되고 있으며 정상조직의 보호가 거의 완벽하게 이루어지고 있으며 방사선을 이용한 암 치료에 대한 평가도 다시 되어야 한다고 사료된다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권15호
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• pp.6595-6597
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• 2015

Objective: To investigate short- and long-term treatment effects and side reactions of lobaplatin plus 5-Fu combined and concurrent radiotherapy in treating patients with inoperable middle-advanced stage esophageal cancer. Methods: Sixty patients with middle-advanced stage esophageal squamous cell cancer were retrospectively analyzed. All patients were administered lobaplatin (50 mg intravenously) for 2 h on day 1, and 5-Fu ($500mg/m^2$) injected intravenously from day 1 to 5 for 1 cycle, in an interval of 21 days for totally 4 cycles. At the same time, late-course accelerated hyperfractionated three-dimensional conformal radiotherapy was performed. Patients were firstly treated with conventional fractionated irradiation (1.8 Gy/d, 5 times/week, a total of 23 treatments, and DT41.4 Gy), and then treated with accelerated hyperfractionated irradiation (1.5 Gy, 2 times/d, a total of 27 Gy in 9 days, an entire course of 6-7 weeks, and DT 68.4Gy). Results: All patients completed treatment, including 10 complete response (CR), 41 partial response (PR), 7 stable disease (SD), and 2 progressive disease (PD). The total effective rate was 85.0% (51/60). Thirty-nine patients had an increased KPS score. One-, 2-, and 3-year survival rates were 85.3%, 57.5%, and 41.7%, respectively. The median survival time was 27 months. The adverse reactions included myelosuppression, which was mainly degree I and II. The occurrence rate of radiation esophagitis was 17.5%. No significant hepatic or renal toxicity was observed. Conclusion: Lobaplatin plus 5-Fu combined with concurrent radiotherapy is safe and effective in treating patients with middle-advanced stage esophageal cancer. However, this result warrants further evaluation by randomized clinical studies.

• Radiation Oncology Journal
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• 제31권3호
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• pp.147-154
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• 2013

Purpose: To evaluate the role of salvage radiotherapy (RT) for the treatment of regional lymph node recurrence (RLNR) after radical surgery in advanced gastric cancer. Materials and Methods: We retrospectively analyzed medical records of 26 patients who underwent salvage treatment after diagnosis of RLNR between 2006 and 2011. Patients with peritoneal seeding or distant metastasis were excluded. Eighteen patients received RT with or without chemotherapy and the other 8 did chemotherapy only without RT. A three-dimensional conformal RT was performed with median dose of 56 Gy (range, 44 to 60 Gy). Sixteen patients had fluoropyrimidine-based chemotherapy, 5 did taxane-based chemotherapy, and irinotecan was applied in 4. Results: With a median follow-up of 20 months (range, 5 to 57 months), median overall survival (OS) and progression-free survival (PFS) after diagnosis of RLNR were 29 months and 12 months in the entire patients, respectively. Radiotherapy (p = 0.007) and disease-free interval (p = 0.033) were statistically significant factors for OS in multivariate analysis. Median OS was 36 months in patients who received RT and 16 months in those who did not. Furthermore, delivery of RT (p < 0.001), complete remission after salvage treatment (p = 0.040) and performance status (p = 0.023) were associated with a significantly better PFS. Gastrointestinal toxicities from RT were mild in most patients. Conclusion: Salvage RT combined with systemic chemotherapy may be an effective treatment managing RLNR from advanced gastric cancer.

• Journal of Radiation Protection and Research
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• 제31권4호
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• pp.187-195
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• 2006

본 연구는 간암 환자의 방사선치료 시에 정상 조직과 간암의 위치에 따른 적절한 조사방향을 찾고자 하였다. 간암의 위치는 Couinaud에 의한 분류법을 이용하여 4군으로 나누었고, 각 군의 용적을 가상의 표적 용적으로 정해서 여러 개의 방사선 치료계획을 세워 정상조직합병증발생률(normal tissue complication probability, NTCP)을 비교하였다. 그룹 I에서는 조사 수를 늘릴수록 정상간의 NTCP가 감소되었으나 6개 이상부터는 일정하였다. 그룹 II에서는 PA(posterior to anterior) 조사가 추가 되었을 때 정상간의 NTCP가 증가하였다. 그룹 III는 표적용적 주변에 정상조직이 많아 조사 방향의 설정에 어려움이 있었고 여러 방향에서의 조사 보다는 RAO(right anterior oblique)와 PA를 이용한 2개의 조사만이 시행되었을 때 정상 간의 NTCP가 가장 낮았다. 그룹 IV에서도 RAO와 PA의 2개 조사로 이루어진 치료계획에서 정상 간의 NTCP 가 가장 낮았다. 본 연구를 통해 간암의 방사선 치료계획 시 간암의 위치와 정상조직의 위치에 따라 NTCP 가 다양하게 나타남을 알 수 있었고, 간암의 방사선치료 계획 시 최적 조사 방향의 설정을 통해 임상적으로 방사선치료를 적용하는 데 유용한 지침이 될 수 있을 것으로 생각된다.

• Asian Pacific Journal of Cancer Prevention
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• 제14권10호
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• pp.5989-5993
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• 2013

Background: Radiation therapy is the mainstay of treatment for nasopharyngeal carcinoma. Importance of tumor coverage and challenges posed by its unique and critical location are well evident. Therefore we aimed to evaluate our radiation treatment plan through dose volume histograms (DVHs) to find planning target volume (PTV) dose coverage and factors affecting it. Materials and Methods: This retrospective study covered 45 histologically proven nasopharyngeal cancer patients who were treated with definitive 3D-CRT and chemotherapy between Feb 2006 to March 2013 at the Department of Oncology, Section Radiation Oncology, Aga Khan University Hospital, Karachi, Pakistan. DVH was evaluated to find numbers of shrinking field (phases), PTV volume in different phases and its coverage by the 95% isodose lines, along with influencing factors. Results: There were 36 males (80%) and 9 females (20%) in the age range of 12-84 years. Stage IVA (46.7%) was the most common stage followed by stage III (31.1). Eighty six point six-percent received induction, 95.5% received concurrent and 22.2% received adjuvant chemotherapy. The prescribed median radiation dose was 70Gy to primary, 60Gy to clinically positive neck nodes and 50Gy to clinically negative neck regions. Mean dose to spinal cord was 44.2Gy and to optic chiasma was 52Gy. Thirty seven point eight-percent patients completed their treatment in three phases while 62.2% required four to five phases. Mean volume for PTV3 was $247.8cm^3$ (50-644.3), PTV4 $173.8cm^3$ (26.5-345.1) and PTV5 $119.6cm^3$ (18.9-246.1) and PTV volume coverage by 95% isodose lines were 74.4%, 85.7% and 100% respectively. Advanced T stage, intracranial extension and tumor volume > $200cm^3$ were found to be important factors associated with decreased PTV coverage by 95% isodose line. Conclusions: 3D CRT results in adequate PTV dose coverage by 95% isodose line. However advanced T stage, intracranial extension and large target volume require more advanced techniques like IMRT for appropriate PTV coverage.

• Radiation Oncology Journal
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• 제30권1호
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• pp.43-48
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• 2012

Purpose: To develop the dose volume histogram (DVH) management software which guides the evaluation of radiotherapy (RT) plan of a new case according to the biological consequences of the DVHs from the previously treated patients. Materials and Methods: We determined the radiation pneumonitis (RP) as an biological response parameter in order to develop DVH management software. We retrospectively reviewed the medical records of lung cancer patients treated with curative 3-dimensional conformal radiation therapy (3D-CRT). The biological event was defined as RP of the Radiation Therapy Oncology Group (RTOG) grade III or more. Results: The DVH management software consisted of three parts (pre-existing DVH database, graphical tool, and $Pinnacle^3$ script). The pre-existing DVH data were retrieved from 128 patients. RP events were tagged to the specific DVH data through retrospective review of patients' medical records. The graphical tool was developed to present the complication histogram derived from the preexisting database (DVH and RP) and was implemented into the radiation treatment planning (RTP) system, $Pinnacle^3$ v8.0 (Phillips Healthcare). The software was designed for the pre-existing database to be updated easily by tagging the specific DVH data with the new incidence of RP events at the time of patients' follow-up. Conclusion: We developed the DVH management software as an effective tool to incorporate the phenomenological consequences derived from the pre-existing database in the evaluation of a new RT plan. It can be used not only for lung cancer patients but also for the other disease site with different toxicity parameters.

• Radiation Oncology Journal
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• 제32권3호
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• pp.187-197
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• 2014

Purpose: We aimed to analyze the treatment outcome and long-term toxicity of 70 Gy hypofractionated intensity-modulated radiotherapy (IMRT) for localized prostate cancer using a customized rectal balloon. Materials and Methods: We reviewed medical records of 86 prostate cancer patients who received curative radiotherapy between January 2004 and December 2011 at our institution. Patients were designated as low (12.8%), intermediate (20.9%), or high risk (66.3%). Thirty patients received a total dose of 70 Gy in 28 fractions over 5 weeks via IMRT (the Hypo-IMRT group); 56 received 70.2 Gy in 39 fractions over 7 weeks via 3-dimensional conformal radiotherapy (the CF-3DRT group, which served as a reference for comparison). A customized rectal balloon was placed in Hypo-IMRT group throughout the entire radiotherapy course. Androgen deprivation therapy was administered to 47 patients (Hypo-IMRT group, 17; CF-3DRT group, 30). Late genitourinary (GU) and gastrointestinal (GI) toxicity were evaluated according to the Radiation Therapy Oncology Group criteria. Results: The median follow-up period was 74.4 months (range, 18.8 to 125.9 months). The 5-year actuarial biochemical relapse-free survival rates for low-, intermediate-, and high-risk patients were 100%, 100%, and 88.5%, respectively, for the Hypo-IMRT group and 80%, 77.8%, and 63.6%, respectively, for the CF-3DRT group (p < 0.046). No patient presented with acute or late GU toxicity ${\geq}$grade 3. Late grade 3 GI toxicity occurred in 2 patients (3.6%) in the CF-3DRT group and 1 patient (3.3%) in the Hypo-IMRT group. Conclusion: Hypo-IMRT with a customized rectal balloon resulted in excellent biochemical control rates with minimal toxicity in localized prostate cancer patients.

• Radiation Oncology Journal
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• 제34권1호
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• pp.18-25
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• 2016

Purpose: Radiotherapy of the neck is known to cause carotid artery stenosis. We compared the carotid artery dose received between volumetric modulated arc therapy (VMAT) and conventional fixed-field intensity-modulated radiotherapy (IMRT) plans in patients with early glottic cancer. Materials and Methods: Twenty-one early glottic cancer patients who previously underwent definitive radiotherapy were selected for this study. For each patient, double arc VMAT, 8-field IMRT, 3-dimensional conformal radiotherapy (3DCRT), and lateral parallel-opposed photon field radiotherapy (LPRT) plans were created. The 3DCRT plan was generated using lateral parallel-opposed photon fields plus an anterior photon field. VMAT and IMRT treatment plan optimization was performed under standardized conditions to obtain adequate target volume coverage and spare the carotid artery. Dose-volume specifications for the VMAT, IMRT, 3DCRT, and LPRT plans were calculated with radiotherapy planning system. Monitor units (MUs) and delivery time were measured to evaluate treatment efficiency. Results: Target volume coverage and homogeneity results were comparable between VMAT and IMRT; however, VMAT was superior to IMRT for carotid artery dose sparing. The mean dose to the carotid arteries in double arc VMAT was reduced by 6.8% compared to fixed-field IMRT (p < 0.001). The MUs for VMAT and IMRT were not significantly different (p = 0.089). VMAT allowed an approximately two-fold reduction in treatment delivery time in comparison to IMRT (3 to 5 minutes vs. 5 to 10 minutes). Conclusion: VMAT resulted in a lower carotid artery dose compared to conventional fixed-field IMRT, and maintained good target coverage in patients with early glottic cancer.

• Radiation Oncology Journal
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• 제37권3호
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• pp.193-200
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• 2019

Purpose: To explore the role of salvage radiotherapy (RT) for recurrent thymoma as an alternative to surgery. Materials and Methods: Between 2007 and 2015, 47 patients who received salvage RT for recurrent thymoma at Yonsei Cancer Center were included in this study. Recurrent sites included initial tumor bed (n = 4), pleura (n = 19), lung parenchyma (n = 10), distant (n = 9), and multiple regions (n = 5). Three-dimensional conformal and intensity-modulated RT were used in 29 and 18 patients, respectively. Median prescribed dose to gross tumor was 52 Gy (range, 30 to 70 Gy), with equivalent doses in 2-Gy fractions (EQD₂). We investigated overall survival (OS), progression-free survival (PFS), and patterns of failure. Local failure after salvage RT was defined as recurrence at the target volume receiving >50% of the prescription dose. Results: Median follow-up time was 83 months (range, 8 to 299 months). Five-year OS and PFS were 70% and 22%, respectively. The overall response rate was 97.9%; complete response, 34%; partial response, 44.7%; and stable disease, 19.1%. In multivariate analysis, histologic type and salvage RT dose (≥52 Gy, EQD₂) were significantly associated with OS. The high dose group (≥52 Gy, EQD₂) had significantly better outcomes than the low dose group (5-year OS: 80% vs. 59%, p = 0.046; 5-year PFS: 30% vs. 14%, p=0.002). Treatment failure occurred in 34 patients; out-of-field failure was dominant (intra-thoracic recurrence 35.3%; extrathoracic recurrence 11.8%), while local failure rate was 5.8%. Conclusion: Salvage RT for recurrent thymoma using high doses and advanced precision techniques produced favorable outcomes, providing evidence that recurrent thymoma is radiosensitive.