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Yao-Ching Wang,
Te-Chun Hsieh,
Chun-Yen Yu,
Kuo-Yang Yen,
Shang-Wen Chen, Shih-Neng Yang,
Chun-Ru Chien,
Shih-Ming Hsu,
Tinsu Pan,
Chia-Hung Kao,
Ji-An Liang
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ABSTRACT: A combination of four-dimensional computed tomography with (18)F-fluorodeoxyglucose positron emission tomography (4D CT-FDG PET) was used to delineate gross tumor volume (GTV) in esophageal cancer (EC). Eighteen patients with EC were prospectively enrolled. Using 4D images taken during the respiratory cycle, the average CT image phase was fused with the average FDG PET phase in order to analyze the optimal standardized uptake values (SUV) or threshold. PET-based GTV (GTV(PET)) was determined with eight different threshold methods using the auto-contouring function on the PET workstation. The difference in volume ratio (VR) and conformality index (CI) between GTV(PET) and CT-based GTV (GTV(CT)) was investigated. The image sets via automatic co-registrations of 4D CT-FDG PET were available for 12 patients with 13 GTV(CT) values. The decision coefficient (R(2)) of tumor length difference at the threshold levels of SUV 2.5, SUV 20% and SUV 25% were 0.79, 0.65 and 0.54, respectively. The mean volume of GTV(CT) was 29.41 ± 19.14 ml. The mean VR ranged from 0.30 to 1.48. The optimal VR of 0.98, close to 1, was at SUV 20% or SUV 2.5. The mean CI ranged from 0.28 to 0.58. The best CI was at SUV 20% (0.58) or SUV 2.5 (0.57). The auto-contouring function of the SUV threshold has the potential to assist in contouring the GTV. The SUV threshold setting of SUV 20% or SUV 2.5 achieves the optimal correlation of tumor length, VR, and CI using 4D-PET/CT images.
Journal of Radiation Research 07/2012; 53(4):594-600. · 1.68 Impact Factor
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ABSTRACT: This study aimed to investigate whether the combination of clinical information, tumor volume and pretreatment SUVmax at the primary tumors might improve the prognostic stratification in pharyngeal cancer (PC) patients treated with radiotherapy (RT). Sixty-two patients with PC (35 oropharynx; 27 hypopharynx) treated with RT were enrolled in this retrospective analysis. All patients received pretreatment FDG- PET or PET/CT. The primary tumor relapse-free survival (PRFS) was calculated according to different variables. The median values of the SUVmax for the primary tumors (SUVp-max) and the gross tumor volume (GTVp) were used to divide patients into two groups. Independent prognosticators were identified by the Cox regression analysis. In this study, the median SUVp-max and GTVp was 11 and 15.5 ml. Patients having tumors with SUVp-max > 11 had a significantly inferior 2-year PRFS (41% vs. 75%, p = 0.003) compared with patients having lower uptake tumors. Multivariate analysis of the PRFS showed two prognostic factors: SUVp-max > 11 (p = 0.04, hazard ratio = 2.67) and GTVp > 15.5 ml (p = 0.03, hazard ratio = 2.88). For patients with a GTVp less than 15.5 ml, there was a more significant impact of SUVmax-p on their PRFS compared to that for those with large ones. We disclosed a higher pretreatment SUVp-max is a predictor for primary recurrence in PC patients treated with RT, particularly for those with smaller tumor volumes. Patients with a large tumor volume or a higher SUVp-max should be considered for requiring more aggressive treatment approaches.
Journal of Radiation Research 06/2012; 53(3):462-8. · 1.68 Impact Factor
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ABSTRACT: The aim of the study was to investigate the predictive role of pretreatment metabolic volume (MTV) in pharyngeal cancer (PC) patients treated with definitive (chemo) radiotherapy.
This retrospective analysis enrolled 64 patients with PC treated with (chemo) radiotherapy. All patients received pretreatment fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT. Four PET segmentation methods were used, namely applying an isocontour at a standardized uptake value (SUV) of either 2.5 or 3.0 (MTV2.5 and MTV3.0) or using fixed thresholds of either 40 or 50 % (MTV40 %, MTV50 %) of the maximum intratumoural FDG activity. Disease-free survival (DFS) and primary relapse-free survival (PRFS) were examined according to cutoffs of the median values for each MTV and the gross tumour volume (GTVp). Independent prognosticators were identified by Cox regression analysis.
With a median follow-up of 24 months, 19 patients died, and 26 patients experienced tumour relapse at primary sites. Multivariate analysis of the DFS showed that MTV2.5 > 13.6 ml was the only predictor of relapse [p = 0.011, hazard ratio = 2.69, 95 % confidence interval (CI) 1.25-5.76]. The independent predictor for PRFS was MTV2.5 > 13.6 ml (p = 0.003, hazard ratio = 3.76, 95 % CI 1.57-8.92), whereas GTVp > 15.5 ml had a marginal impact on PRFS (p = 0.06, hazard ratio = 3.54, 95 % CI 0.97-11.85). Patients having tumours with MTV2.5 > 13.6 ml had a significantly inferior 2-year PRFS compared with patients who had lower MTV2.5 tumours (39 vs 72 %, respectively, p = 0.001).
For PC patients treated with definitive (chemo)radiotherapy, pretreatment MTV2.5 volume achieved the best predictive value for primary recurrence, and the same value was also a prognosticator for DFS.
European Journal of Nuclear Medicine 04/2012; 39(8):1297-305. · 4.53 Impact Factor
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International journal of radiation oncology, biology, physics 12/2011; 81(5):1592. · 4.59 Impact Factor
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ABSTRACT: To investigate the prognostic value of the volume reduction rate (VRR) in patients with head-and-neck cancer treated with intensity-modulated radiotherapy (IMRT).
Seventy-six patients with oropharyngeal cancer (OPC) and another 76 with hypopharyngeal cancer (HPC) were enrolled in volumetric analysis. All patients received allocated radiotherapy courses. Adaptive computed tomography was done 4 to 5 weeks after the start of IMRT. Primary tumor volume measurement was derived using separate images for the pretreatment gross tumor volume (pGTV) and the interval gross tumor volume.
In the OPC group, the pGTV ranged from 6.6 to 242.6 mL (mean, 49.9 mL), whereas the value of the VRR ranged from 0.014 to 0.74 (mean, 0.43). In HPC patients, the pGTV ranged from 4.1 to 152.4 mL (mean, 35.6 mL), whereas the VRR ranged from -1.15 to 0.79 (mean, 0.33). Multivariate analysis of the primary tumor relapse-free survival for OPC revealed three prognostic factors: T4 tumor (p = 0.0001, hazard ratio 7.38), pGTV ≥20 mL (p = 0.01, hazard ratio 10.61), and VRR <0.5 (p = 0.001, hazard ratio 6.49). Multivariate analysis of the primary tumor relapse-free survival for HPC showed two prognostic factors: pGTV ≥30 mL (p = 0.001, hazard ratio 2.87) and VRR <0.5 (p = 0.03, hazard ratio 2.25).
The VRR is an outcome predictor for local control in OPC and HPC patients treated with IMRT. Those with large tumor volumes or a VRR <0.5 should be considered for a salvage operation or a dose-escalation scheme.
International journal of radiation oncology, biology, physics 03/2011; 79(4):1096-103. · 4.59 Impact Factor
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ABSTRACT: This study aimed to determine whether Tl-201 single photon emission CT (SPECT) is potentially useful in differentiating false-positive fluorodeoxyglucose positron emission tomography (FDG-PET) findings caused by osteoradionecrosis (ORN) from recurrent head and neck cancer after radiotherapy.
Five patients were recruited. Dual-phase FDG-PET and dual-phase Tl-201 SPECT were performed for each patient.
All 5 patients proved to have ORN without recurrent cancer. By visual interpretation, the results were 4 positive versus 1 negative for PET, and 4 negative versus 1 positive for Tl-201 SPECT. The Tl-201 SPECT clarified 3 of the 4 false-positive PETs to be ORN. Dual-phase semiquantitative studies showed decreased standardized uptake value (SUV) over time in 3 of the 4 false-positive PETs and decreased lesion/background ratio over time in the false-positive Tl-201 SPECT.
The Tl-201 SPECT may help clarify suspected false-positive FDG uptake caused by ORN. Dual-phase FDG-PET and dual-phase Tl-201 SPECT may also have some value.
Head & Neck 12/2010; 32(12):1648-54. · 2.40 Impact Factor
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Clinical nuclear medicine 05/2010; 35(5):381-3. · 3.92 Impact Factor
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ABSTRACT: This study aimed to assess the dose-rate effect of (192)Ir source activity on pelvic control and late complications following high-dose-rate intracavitary brachytherapy (HDRICB) for cervical cancer patients. Two hundred and twelve patients were enrolled in this study. They were treated with external beam radiotherapy to the pelvis, after which HDRICB was performed using (192)Ir remote after-loading at 1-week intervals for 4 or 5 sessions. Source activity was defined as the average of source activity in each HDRICB session. Dose-rate effect was analyzed after stratification of stage and biologically effective dose (BED). The 5-year pelvic relapse-free survival was 88% for all patients. Forty-two patients developed late rectal complications (13 grade 1, 23 grade 2, 6 grade 3-4). Twenty-seven patients had grade 2 and higher late bladder complications (14 grade 2, 13 grade 3-4). There was no dose-rate effect on pelvic control or complications when source activity was stratified. Multivariate analysis demonstrated a high risk of grade 2 and higher rectal sequelae in patients whose rectal BED >or= 110 Gy(3) (p = 0.039, hazard ratio 2.05). The high risk factors for grade 2 and higher bladder complications were a bladder BED >or= 100 Gy(3) (p = 0.03, hazard ratio 4.37). This study demonstrated no dose-rate effect of (192)Ir source in HDRICB for cervical cancer in terms of pelvic control or radiation injuries. Careful monitoring of the BED values for rectum and bladder is a scrutinizing factor for minimizing late sequelae.
Journal of Radiation Research 03/2010; 51(2):173-9. · 1.68 Impact Factor
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ABSTRACT: To define a suitable threshold setting for gross tumor volume (GTV) when using 18Fluoro-deoxyglucose positron emission tomography and computed tomogram (PET/CT) for radiotherapy planning in head and neck cancer (HNC).
Fifteen HNC patients prospectively received PET/CT simulation for their radiation treatment planning. Biological target volume (BTV) was derived from PET/CT-based GTV of the primary tumor. The BTVs were defined as the isodensity volumes when adjusting different percentage of the maximal standardized uptake value (SUVmax), excluding any artifact from surrounding normal tissues. CT-based primary GTV (C-pGTV) that had been previously defined by radiation oncologists was compared with the BTV. Suitable threshold level (sTL) could be determined when BTV value and its morphology using a certain threshold level was observed to be the best fitness of the C-pGTV. Suitable standardized uptake value (sSUV) was calculated as the sTL multiplied by the SUVmax.
Our result demonstrated no single sTL or sSUV method could achieve an optimized volumetric match with the C-pGTV. The sTL was 13% to 27% (mean, 19%), whereas the sSUV was 1.64 to 3.98 (mean, 2.46). The sTL was inversely correlated with the SUVmax [sTL = -0.1004 Ln (SUVmax) + 0.4464; R2 = 0.81]. The sSUV showed a linear correlation with the SUVmax (sSUV = 0.0842 SUVmax + 1.248; R2 = 0.89). The sTL was not associated with the value of C-pGTVs.
In PET/CT-based BTV for HNC, a suitable threshold or SUV level can be established by correlating with SUVmax rather than using a fixed threshold.
Radiation Oncology 01/2010; 5:76. · 2.32 Impact Factor
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ABSTRACT: We aimed to analyze the outcomes and cost-effectiveness of gamma knife radiosurgery (GKRS) and whole brain radiotherapy (WBRT) for multiple metastatic brain tumors. Over a period of 5 years, 156 patients with multiple metastatic brain tumors were enrolled and freely assigned by the referring doctors to either gamma knife radiosurgery (GKRS, Group A, n=56), or to whole brain radiotherapy (WBRT, Group B, n=100). The follow-up time was set at 1200 days (3.3 years) post-treatment. The number of tumors, patient age, extent of systemic disease and Karnofsky performance scale (KPS) score, were recorded and recursive partitioning analysis used. The outcomes analyzed were: mortality, survival time, neurological complications, post-treatment KPS score, quality-adjusted life years (QALY), and cost-effectiveness. A paired t-test was used for statistical analysis. Mortality rates for patients receiving GKRS and WBRT were 81.1% and 93.0%, respectively (p=0.05). The mortality rate was lower for GKRS (74.4%) than for WBRT (97.1%) in patients with initial KPS70 (p=0.02). The mortality rate was also significantly lower for GKRS (78.9%) than WBRT (95.5%) in patients with 2-5 tumors (p<0.05). Post-treatment KPS score (mean+/-standard deviation [s.d.] was higher for patients receiving GKRS (73.8+/-13.2) than for those receiving WBRT (45.5+/-26.0), p<0.01. The median survival time for GKRS and WBRT was 9.5 months and 8.3 months, respectively, p=0.72. The mean (+/- s.d.) QALY was 0.76+/-0.23 for GKRS and 0.59+/-0.18 for WBRT, respectively (p<0.05). The cost-effectiveness per unit of QALY was better for the GKRS treatment (US$10,381/QALY) than in the WBRT treatment (US$17,622/QALY), p<0.05. The cost-effectiveness per KPS score was also higher for the GKRS treatment (US$139/KPS score) than for WBRT (US$229/KPS score), p<0.01. Thus, the mortality rate for multiple metastatic brain tumors treated by GKRS is significantly better with a good initial KPS score and when the tumor number is 2-5. GKRS results in a better post-treatment KPS score, QALY, and higher cost-effectiveness than WBRT for treating multiple metastatic brain tumors.
Journal of Clinical Neuroscience 05/2009; 16(5):630-4. · 1.25 Impact Factor
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ABSTRACT: This study aimed to assess the predictive values of geometrical sparing factors for the rectum and bladder in high-dose-rate intracavitary brachytherapy (HDRICB) for Grade 2 and higher late sequelae in patients with cervical cancer.
A total of 392 patients were enrolled in this study. They were treated with external beam radiotherapy to the pelvis, after which HDRICB was performed using Ir-192 remote after-loading at 1-week intervals for three or four sessions. The geometrical sparing factor (GSF) was defined as the average of the ratios between the reference doses and the Point A dose.
A total of 46 patients (11.7%) had Grade 2 or higher late rectal complications (36 Grade 2, 9 Grade 3, and 1 Grade 4). In all, 32 patients (8.2%) had Grade 2 or higher late bladder complications (14 Grade 2, 16 Grade 3, and 2 Grade 4). Multivariate analysis demonstrated a high risk of rectal sequelae in patients who developed bladder complications (p = 0.0004, hazard ratio 3.54) and had a rectal GSF greater than 0.7 (p = 0.01, hazard ratio 1.99). The high risk factors for bladder complications were development of rectal complications (p = 0.0004, hazard ratio 3.74), concurrent chemotherapy (p = 0.0001, relative risk 3.94), and a bladder GSF greater than 0.9 (p = 0.01, hazard ratio, 2.53).
This study demonstrates the predictive value of GSFs in HDRICB for cervical cancer. Patients with rectal GSFs greater than 0.7 or bladder GSFs greater than 0.9 are at risk for Grade 2 and higher late sequelae.
International journal of radiation oncology, biology, physics 05/2009; 75(5):1335-43. · 4.59 Impact Factor
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ABSTRACT: To investigate the prognostic value of volumetric analysis in patients with stage III-IVA hypopharyngeal cancer treated with concurrent chemoradiotherapy (CCRT).
Seventy-six stage III-IVA hypopharyngeal cancer patients without bulky lymph nodes were enrolled for a volumetric analysis. The pyriform sinus was the principal site of involvement in the 63 cases. All patients were allocated a course of CCRT. Tumor volume measurement was derived using separate calculations for the primary tumor volume (pGTV) and the nodal tumor volume (nGTV).
The pGTV ranged from 3.8 to 152.4 mL (mean, 33.4 mL). The 3-year cause-specific survival (CSS) was 75% for those with a pGTV <30 mL and 20% when the pGTV was >or=30 mL (p = .0001). Furthermore, the 3-year primary tumor relapse-free survival (PRFS) was 72% for those with a pGTV <30 mL and 23% when the pGTV were >or=30 mL (p = .0001). The 3-year PRFSs for <30 mL and >or=30 mL were 74% and 25% for stage III disease (p = .01) and 65% and 22% for stage IVA tumors (p = .01), respectively. Multivariate analyses of the CSS revealed a single prognostic factor, namely pGTV <30 mL versus >or=30 mL (p = .0001, hazard ratio 2.84). Multivariate analyses of the PRFS gave a similar finding, with a pGTV >or=30 mL (p = .0001, hazard ratio 2.55) being significant.
A patient's pGTV is a strong outcome predictor for hypopharyngeal cancer treatment using CCRT. Therefore, a selected group of patients, mainly those with tumor volumes <30 mL should be considered for laryngeal preservation.
Head & Neck 03/2009; 31(6):709-16. · 2.40 Impact Factor
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ABSTRACT: The aim of this study was to investigate the prognostic significance of pretreatment levels of carcinoembryonic antigen (CEA) for treatment outcome in comparison with squamous cell carcinoma antigen (SCC) in cervical cancer patients following concurrent chemoradiotherapy (CCRT).
A total of 148 patients with stage IB2-IVA squamous cell carcinoma of the uterine cervix who were treated with a full course of CCRT were included for analysis. The pretreatment blood samples of tumor markers were obtained before initiation of CCRT. Values for SCC <2 and CEA <5 ng/ml, respectively, were regarded as normal. Cox's proportional hazards model was performed for risk stratification for disease-free survival (DFS) and cause-specific survival (CSS).
Pretreatment CEA and SCC levels were elevated in 37.2 and 64.2% of the patients, respectively. Positive pelvic lymph node, stage and pretreatment CEA levels >10 ng/ml were three independent prognostic factors for DFS and CSS. The 5-year DFS for the low- and high-CEA groups was 80 and 56%, respectively (p = 0.02, hazard ratio 2.6), whereas the 5-year CSS for the low- and high-CEA groups was 84 and 63%, respectively (p = 0.01, hazard ratio 3.2).
Despite lower sensitivity, pretreatment CEA levels >10 ng/ml predict a poor outcome in advanced squamous cell carcinoma of the cervix.
Tumor Biology 09/2008; 29(4):255-61. · 1.94 Impact Factor
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ABSTRACT: To identify risk factors for disease-free survival (DFS) and para-aortic lymph node (PALN) metastasis in advanced cervical cancer patients after concurrent chemoradiotherapy (CCRT) using risk stratification.
In total, 148 patients with stage IB2-IVA cervical cancer without PALN metastasis treated with a full course of CCRT were included for analysis. Radiotherapy consisted of external beam irradiation followed by four courses of high-dose rate intracavitary brachytherapy using 6.0 Gy to point A. Chemotherapy consisted of weekly cisplatin at a dose of 40mg/m(2) for a planned six cycles. Cox's proportional hazards model was used for risk stratification for DFS and PALN relapse-free survival.
Patients were divided into low- and high-risk groups. The low-risk group was composed of patients with stage IB-IIB disease without enlarged pelvic nodes, whereas the high-risk group was comprised of patients with stage IB2-IIB tumours with enlarged nodes or those with stage III-IVA disease. The 4-year DFS for the low- and high-risk groups was 83 and 52%, respectively (P=0.0001, relative risk 4.51, 95% confidence interval 1.3-10.7), whereas the 4-year PALN metastasis-free survival for the low- and high-risk groups was 92 and 61%, respectively (P=0.0003, relative risk 4.93, 95% confidence interval 1.2-12.5).
The risk of failure in advanced cervical cancer patients treated in the CCRT era can be predicted. For patients with high risk of PALN relapse, this study can provide patient selection criteria when considering prophylactic PALN irradiation.
Clinical Oncology 09/2008; 20(9):683-90. · 2.07 Impact Factor
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ABSTRACT: To compare survival data between patients who had surgery followed by concomitant chemoradiation therapy (CCRT) versus CCRT followed by early surgical salvage.
Retrospective study.
We retrospectively analyzed 202 patients with hypopharyngeal carcinoma (HPC) who were treated with different treatment strategy according to the choice of the patients by surgery first or CCRT first. In 72 (35.6%) cases, the primary treatment was surgery. Postoperative radiation therapy was given to 47 patients. Radiation therapy was the primary treatment in 130 (64.4%) patients; among them, 69 (34.2%) patients received salvage surgery within 2 months after CCRT course if there was a residual tumor visible on post-CCRT CT image or clinically residual tumor.
The 5-year disease-specific survival rate was 80% for stage I-II, 44.8% for stage III, and 14.3% for stage IV disease. Surgery plus concomitant chemoradiotherapy led to a better survival rate than CCRT plus salvage surgery in patients with stage III-IV HPC.
Otolaryngology Head and Neck Surgery 12/2007; 137(5):711-6. · 1.72 Impact Factor
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ABSTRACT: To test, though a control-cohort study, the hypothesis that concurrent chemoradiotherapy (CCRT) using weekly cisplatin, plus high-dose rate intracavitary brachytherapy (HDRICB) is superior to radiation (RT) alone in patients with advanced cervical cancer.
A total of 171 patients with Stage IIB-III cervical cancer were enrolled in this study. Seventy patients were treated with CCRT and the results were compared with those of 101 patients who had been treated with RT using the same protocol at an early period. RT consisted of 45 Gy in 25 fractions to the whole pelvis, followed by a 12.6-Gy boost to the parametrium. Four courses of HDRICB using 6.0 Gy to Point A were performed. Chemotherapy consisted of weekly cisplatin at a dose of 40 mg/m(2) for 5-6 cycles.
The 4-year actuarial survival was 74% for the CCRT group and 68% for the RT group (p = 0.60). The 4-year pelvic relapse-free survival was 87% for the CCRT group and 85% for the RT group (p = 0.37). The 4-year distant metastases-free survival was 75% for the CCRT group and 76% for the RT group (p = 0.44). The cumulative incidence of gastrointestinal and genitourinary injuries of grade 3 or above was 14.3% for the CCRT group and 7.9% for the RT group (p = 0.19).
This study did not show a survival benefit of CCRT with weekly cisplatin and HDRICB for Stage II-III cervical cancer, nor did it demonstrate a significant increase of late complications when comparing with RT alone.
International Journal of Radiation OncologyBiologyPhysics 01/2007; 66(5):1370-7. · 4.11 Impact Factor
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ABSTRACT: To investigate the value of pretreatment computed tomography (CT) volumetric analysis for the prediction of treatment outcome in patients with hypopharyngeal cancer (HPC) treated by definitive radiotherapy (RT).
From January 2000 through February 2004, 63 patients with HPC were enrolled for a retrospective analysis. The pyriform sinus was the principle site of involvement in 62 cases. All patients received with 1.8 Gy daily to a total dose of 68.4 to 73.8 Gy (median, 70.2 Gy). Contrast-enhanced CT images were transferred to a planning system. Tumor volume measurement was derived from summation of the primary and metastatic nodal tumor.
With a median follow-up of 38 (range, 24-68) months, the 5 year local relapse-free survival (LRFS) was 83% for patients with T1 to T2 disease, 46% for those with T3 disease, and 40% for those with T4 disease (P = .01). The 5 year LRFS was 75% for those with tumors less than 40 mL and 26% when volumes were 40 mL of larger (P = .0001). For patients with T3 to T4 disease, the 5 year LRFS was 70% for those with tumors less than 40 mL and 24% when volumes were 40 mL or larger (P = .0005). Multivariate analyses of local relapse-free survival revealed two prognostic factors: tumor volume more than 40 mL and the involvement of the larynx.
CT-based tumor volumes are a strong predictor of outcomes for HPC treated using definitive RT. A selected group of patients, mainly those with tumor volumes less than 40 mL, should be considered for laryngeal preservation.
The Laryngoscope 12/2006; 116(11):2012-7. · 1.75 Impact Factor
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ABSTRACT: This study compared the target volume coverage and normal tissues sparing of simultaneous integrated boost (SIB-IMRT, 1-phase) and sequential-IMRT (2-phase) for nasopharyngeal carcinoma (NPC). Fourteen consecutive patients with newly diagnosed primary NPC were enrolled in this study. The CT images were transferred to a commercial planning system for structural delineation. The gross tumor volume (GTV) included gross nasopharyngeal tumor and involved lymph nodes of more than 1-cm diameter. The clinical target volume (CTV) modeled two regions considered to represent different risks. CTV1 encompassed the GTV with 5-10-mm margin of adjacent tissues. CTV2 encompassed ipsilateral or contralateral elective nodal regions at risk of harboring microscopic tumor. A commercial IMRT treatment planning system (Eclipse Version 7.1) was used to provide treatment planning. Seven fixed-gantry (0 degrees, 50 degrees, 100 degrees, 150 degrees, 210 degrees, 260 degrees, 310 degrees ) angles were designated. The 14 patients were treated with sequential-IMRT, and treatment was then replanned with an SIB strategy to compare the dosimetric difference. For the sequential strategy, the dose delivered to CTV1/CTV2 in the first course was 54 Gy (1.8 Gyx30 Fr); while CTV1 was boosted by an additional 16.2 Gy (1.8 Gyx9 Fr) in the second course. For SIB-IMRT, the dose prescribed to CTV1 was 69.7 Gy (2.05 Gyx34 Fr); 56.1 Gy was given to CTV2 (1.65 Gyx34 Fr). A statistical analysis of the dose-volume-histogram of target volumes and critical organs was performed. Paired Student's t-test was used to compare the dosimetric differences between the two techniques. The mean dose to CTV1 was 101.7+/-2.4% and 102.3+/-3.1% of the prescribed dose for SIB-IMRT and sequential-IMRT, respectively. The mean CTV2 dose was 109.8+/-4.7% of the prescribed dose for SIB-IMRT and 112.6+/-6.0% of the prescribed dose for sequential-IMRT. The maximal dose to the spinal cord was 4489+/-495 cGy and 3547+/-767 cGy for SIB and sequential-IMRT (p=0.0001), respectively. The maximal dose to brain stem was significantly higher using SIB technique (5284+/-551 cGy) than sequential-IMRT (4834+/-388 cGy) (p=0.0001). The mean dose to the parotid gland and ear apparatus was significantly lower using SIB-IMRT. The mean dose to the right/left parotids was 2865+/-320 cGy/2903+/-429 cGy and 3567+/-534 cGy/3476+/-489 cGy for SIB and sequential-IMRT, respectively (p=0.0001). Target coverage was the same for both techniques; the dose distribution in the elective nodal area with SIB was superior to that with sequential-IMRT. SIB-IMRT provides better sparing of parotid gland and inner ear structures. Extra caution should be taken when applying SIB-IMRT since critical organs close to the boost volume may receive higher doses.
Medical Dosimetry 02/2005; 30(4):219-27. · 1.00 Impact Factor
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ABSTRACT: This study aimed to correlate and compare the predictive values of rectal and bladder reference doses of uniform external beam radiotherapy without shielding and high-dose-rate intracavitary brachytherapy (HDRICB) with late sequelae in patients with uterine cervical cancer.
Between September 1992 and December 1998, 154 patients who survived more than 12 months after treatment were studied. Initially, they were treated with 10-MV X-rays (44 to 45 Gy/22 to 25 fractions over 4 to 5 weeks) to the whole pelvis, after which HDRICB was performed using (192)Ir remote afterloading at 1-week intervals for 4 weeks. The standard prescribed dose for each HDRICB was 6.0 Gy to point A. Patient- and treatment-related-factors were evaluated for late rectal complications using logistic regression modeling.
The probability of rectal complications showed better correlation of dose-response with increasing total ICRU (International Committee on Radiotherapy Units and Measurements) rectal dose. Multivariate logistic regression demonstrated a high risk of late rectal sequelae in patients who developed rectal complications (p = 0.0001;relative risk, 15.06;95% CI, 2.89 approximately 43.7) and total ICRU rectal dose greater than 16 Gy (p = 0.02;relative risk, 2.07;95% CI, 1.13 approximately 4.55). The high risk factors for bladder complications were seen in patients who developed rectal complications (p = 0.0001;relative risk, 15.2;95% CI, 2.81 approximately 44.9) and total ICRU bladder dose greater than 24 Gy (p = 0.02;relative risk, 8.93;95% CI, 1.79 approximately 33.1).
This study demonstrated the predictive value of ICRU rectal and bladder reference dosing in HDRICB for patients receiving uniform external beam radiation therapy without central shielding. Patients who had a total ICRU rectal dose greater than 16 Gy, or a total ICRU bladder dose over 24 Gy, were at risk of late sequelae.
International Journal of Radiation OncologyBiologyPhysics 11/2004; 60(2):663-71. · 4.11 Impact Factor
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ABSTRACT: To evaluate the risk factors for nonrectal radiation-induced intestinal injury (NRRIII) following adjuvant radiotherapy (RT) for cervical cancer using a retrospective review of medical records.
From September 1992 to December 1998, 164 patients with uterine cervical cancer that had completed their allocated adjuvant radiotherapy at the Chinese Medical University Hospital were enrolled for NRRIII analysis. The patients were classified into two groups according to the extent of surgery. Group A consisted of 110 patients (International Federation of Gynecology and Obstetrics [FIGO] stage: IB, n = 87; IIA, n = 21; IIB, n = 2) undergoing radical hysterectomy and bilateral pelvic lymph node dissection, while Group B was composed of 54 analogs receiving adjuvant radiotherapy following incident extrafascial hysterectomy. Treatment consisted of external beam radiotherapy (EBRT) and high-dose-rate intravaginal brachytherapy (HDRIVB). Initially, the whole pelvis was treated with 10 MV X-rays. After irradiation (44 Gy in 22 fractions over 4-5 weeks), the field was limited to the true pelvis and a further 10-20 Gy delivered in 5-10 fractions. For 21 patients in group A without pelvic lymph node metastasis or lymphovascular invasion, the radiation field was confined to the lower pelvis, with a prescribed dose of 50-58 Gy delivered over 5-6 weeks. HDRIVB was performed using an Ir-192 remote after-loading technique at 1-week intervals. A total of 159 patients (97%) received two insertions, while 5 had only one. The standard prescribed HDRIVB dose was 7.5 Gy to the vaginal surface. Logistic regression analysis was performed for assessment of the factors associated with NRRIII.
After 38-119 months of follow-up (median, 60), 22 patients (13.4%) developed Radiation Therapy Oncology Group (RTOG) grade 2 or greater NRRIII at a median latency of 18 months (range, 5-48). Four patients were diagnosed as grade 3 complications requiring surgery and three had expired. The independent factors for NRRIII were radical hysterectomy (P = 0.04, relative risk 2.45), lower-pelvic dose >54 Gy (P = 0.0001, relative risk 10.27), and age over 60 years (P = 0.001, relative risk 5.45). The incidence of NRRIII for patients receiving whole and lower-pelvic irradiation was 14.5% and 10.6%, respectively (P = 0.45). Although there was no statistical significance comparing the two external beam irradiation strategies in terms of NRRIII, all four patients with grade 3 NRRIII underwent whole pelvic irradiation.
This study identifies three predictive factors for the development of NRRIII following adjuvant radiotherapy for cervical cancer. Limiting the EBRT dose to less than 54 Gy, meticulous patient selection in the elderly, careful planning of the irradiated field, and the constraint of vaginal brachytherapy are four approaches to optimization of postoperative adjuvant radiotherapy.
Gynecologic Oncology 11/2004; 95(1):208-14. · 3.89 Impact Factor
