Clinical Target Volume For Radiotherapy Research Articles

Is CT-based selective nodal irradiation safe for clinical stage N0-1 LD-SCLC patients?

e18551 Background: Radiotherapy plays an important role in the management of limited-disease small-cell lung cancer (LD-SCLC). However, volume of irradiation remains unanswered as well as optimal total dose, timing and sequencing of radiation. In this study, we compared the clinical lymph node staging with pathological staging, with the aim of investigating the safety of CT-based selective nodal irradiation for clinical stage N0-1 LD-SCLC patients. Methods: From July 2004 to March 2012, 20 potentially operable patients with clinical stage N0-1 LD-SCLC underwent contrast-enhanced CT scans and other routine initial staging procedures followed by radical resection of primary tumor and systemic intra-thoracic lymph node dissection. The results of reviewing clinical staging for the mediastinal lymph node metastases were compared with pathologic findings. Results: Preoperative nodal staging was compared with postoperative pathological staging, 35% (7 of 20) of patients were under staged by clinical staging. Of all the 7 patients with mediastinal lymph node metastases, 4 patients (57.1%) had subcrinal nodes (station 7) metastases, 1 had right upper paratracheal nodes (station 2R) metastases, 1 had left lower paratracheal nodes (station 4L) metastases, 1 had aortopulmonary nodes (station 5) metastases. Conclusions: CT-based selective nodal irradiation for LD-SCLC may result in geographical miss in clinical stage N0-1 patients. Mediastinal lymph node regions especially the subcrinal nodes should be contained in the clinical target volume for radiotherapy.

Controversy and consensus on the delineation of clinical target volume in radiotherapy for esophageal cancer

Controversy and consensus on the delineation of clinical target volume in radiotherapy for esophageal cancer

Value of pathological features in defining the longitudinal margin of the clinical target volume in radiotherapy of esophageal squamous-cell carcinoma

Objective To study the characteristics of microscopic spread of esophageal squamous-cell carcinoma (ESCC) and the influence of clinicopathological features on it to help define the clinical target volume (CTV) margin in radiotherapy.Methods Sixty-four surgical specimens of ESCC were observed for longitudinal microscopic spread per centimeter both proximally and distally from the tumor.The shrinkage ratio of each specimen was calculated and used for tissue incision.Results The further the distance beyond the tumor, the lower the incidence there was of microscopic spread.Positive rates of microscopic spread in group 3 cm of proximal and distal were 4.8% and 6.9%, respectively, and in group 4 cm were both 3.6%.Tumors longer than 5 cm in length,with poorer differentiation, lymph nodes metastasis and more aggressive phase had higher positive rates (79.3% vs 45.7%,77.4% vs 45.5%,76.0% vs 51.2%,70.5% vs 40.0%,χ2=7.52,6.86,3.91,5.36;P=0.006,0.009,0.042,0.021).Differentiation and tumor length were main factors contributing to microscopic spread (χ2=0.19,4.82;P=0.020,0.017).Conclusions To cover 95% of the microscopic spread,a margin of 3.0 cm proximal and 4.0 cm distal beyond gross tumor volume is needed and as to 90%, a margin of 3.0 cm both proximal and distal is needed.Moreover, the influence of pathological features should be taken into account. Key words: Esophageal neoplasms; Pathological features; Radiotherapy; Clinical target volume

Distributions of primary nasopharyngeal carcinoma tumor and patterns of skull base erosion detected by magnetic resonance imaging

To evaluate the distributions of primary nasopharyngeal carcinoma (NPC) and the patterns of skull base involvement in NPC patients using magnetic resonance imaging (MRI). After the approval of institutional review board and informed consent, 838 consecutive newly-diagnosed and untreated NPC patients were examined by MRI. Their MR images were reviewed by two independent radiologists. Among all cases, the incidence rates of superior side and post-superior side involvement were 98.57% (826/838) and 98.21% (823/838) respectively. The differences were not significant between these two sides (P > 0.05). Lateral side erosion was demonstrated in 784 (93.56%) cases. Posterior side was involved in 391 (46.66%) cases. The total incidence rate of skull base involvement was 65.51% (549/838). According to the anatomic site, the pathways of skull base involvement were classified into 5 spreading routes: anterior; superior; super-lateral; super-anterior and super-posterior. According to the incidence rates and the results of chi-square test, the anatomic sites around the nasopharynx were classified into three groups of risk grades: high-risk (≥ 35%), medium-risk (≥ 5% - 35%) and low-risk (< 5%). Skull base involvement of NPC spreads stepwise from proximal site to more distal sites. The area of skull base involvement in NPC is classified into high-grade, medium-grade and lower-grade groups respectively. The high and medium-grade groups are related with T3 stage while the lower-grade group T4 stage. Thus T3 stage should be subdivided into T3a and T3b. These schemes may be useful in a more accurate NPC staging and a delineation of clinical target volume for radiotherapy in NPC patients.

Prospective Evaluation of Microscopic Extension using Whole-mount Preparation in Patients with Hepatocellular Carcinoma: Definition of Clinical Target Volume for Radiotherapy

Prospective Evaluation of Microscopic Extension using Whole-mount Preparation in Patients with Hepatocellular Carcinoma: Definition of Clinical Target Volume for Radiotherapy

Prospective evaluation of microscopic extension using whole-mount preparation in patients with hepatocellular carcinoma: Definition of clinical target volume for radiotherapy

BackgroundTo define the clinical target volume (CTV) for radiotherapy in patients with hepatocellular carcinoma (HCC).MethodsA prospective study was conducted to histologically evaluate the presence and the distance of microscopic extension (ME) for resected HCC on the basis of examination of whole-mount preparations of carcinoma tissue sections.ResultsA total of 380 whole-mount slides prepared from tumor samples of 76 patients with HCC were examined. Patients with elevated pretreatment AFP levels exhibited higher risk of ME as compared to those with normal pretreatment AFP levels (93.9% vs. 69.8%, P < 0.01). ME positivity was 16.7% for Grade 1, 79.1% for Grade 2, and 96.3% for Grade 3 tumors (P < 0.01). The mean distance of ME was 0.0 ± 0.1 mm (range 0-0.2 mm) for Grade 1, 0.9 ± 0.9 mm (range 0-4.5 mm) for Grade 2, and 1.9 ± 1.9 mm (range 0-8.0 mm) for Grade 3 tumors (P < 0.01).ConclusionsThe CTV margins for tumor Grades 1, 2, and 3 HCC, are recommended to be 0.2 mm, 4.5 mm, and 8.0 mm beyond the gross tumor margin, respectively, to account for possible ME of the tumors in all patients.

Impact of the pattern of lymph node metastasis on the clinical target volume in radiotherapy for thoracic esophageal squamous cell carcinoma

To study the pattern of lymph node metastasis of thoracic esophageal squamous cell carcinoma (ESCC) after esophagectomy and its impact on the clinical target volume (CTV) delineation in radiotherapy fpr thoracic ESCC. The pattern of lymph node metastasis was retrospectively analyzed in 1077 patients with primary thoracic ESCC. All patients received esophagectomy with two- or three-field lymphadenectomy. The clinicopathologic factors related to lymph node metastasis were then analyzed using logistic regression analysis. The rates of cervical, upper mediastinal, middle mediastinal, lower mediastinal and abdominal cavity lymph node metastasis were 16.7%, 33.3%, 11.1%, 5.6% and 5.6%, respectively. The rates of those node metastasis in the middle thoracic ESCC were 4.0%, 3.8%, 28.5%, 7.1% and 17.1%, respectively, and the rates of those node metastasis in the lower thoracic ESCC were 1.5%, 3.0%, 22.7%, 37.0% and 33.2%, respectively. The depth of tumor invasion, histologic differentiation and the length of tumor were showed to be statistically most significant risk factors of lymph node metastasis of ESCC (P < 0.001). The depth of tumor invasion, histologic differentiation, and length of tumor were closely correlated with lymph node metastasis of ESCC. All these factors and tumor location should be considered comprehensively when designing the target volume for radiotherapy.

Delineation of the neck clinical target volume in radiotherapy for head and neck cancers

放射治疗是头颈部肿瘤主要的治疗手段之一.适形治疗技术的发展和影像学手段的进步为选择性放射治疗的实现提供了条件.根据NO-1期、N2-3期及术后颈部临床靶体积勾画指南行选择性颈部照射,不仅能将局部复发率控制在15%左右,而且能够减少周围正常组织及敏感器官的受照体积和剂量,从而提高治疗比。

Clinicopathologic Analysis of Microscopic Extension in Lung Adenocarcinoma: Defining Clinical Target Volume for Radiotherapy

To determine the gross tumor volume (GTV) to clinical target volume margin for non-small-cell lung cancer treatment planning. A total of 35 patients with Stage T1N0 adenocarcinoma underwent wedge resection plus immediate lobectomy. The gross tumor size and microscopic extension distance beyond the gross tumor were measured. The nuclear grade and percentage of bronchoalveolar features were analyzed for association with microscopic extension. The gross tumor dimensions were measured on a computed tomography (CT) scan (lung and mediastinal windows) and compared with the pathologic dimensions. The potential coverage of microscopic extension for two different lung stereotactic radiotherapy regimens was evaluated. The mean microscopic extension distance beyond the gross tumor was 7.2 mm and varied according to grade (10.1, 7.0, and 3.5 mm for Grade 1 to 3, respectively, p < 0.01). The 90th percentile for microscopic extension was 12.0 mm (13.0, 9.7, and 4.4 mm for Grade 1 to 3, respectively). The CT lung windows correlated better with the pathologic size than did the mediastinal windows (gross pathologic size overestimated by a mean of 5.8 mm; composite size [gross plus microscopic extension] underestimated by a mean of 1.2 mm). For a GTV contoured on the CT lung windows, the margin required to cover microscopic extension for 90% of the cases would be 9 mm (9, 7, and 4 mm for Grade 1 to 3, respectively). The potential microscopic extension dosimetric coverage (55 Gy) varied substantially between the stereotactic radiotherapy schedules. For lung adenocarcinomas, the GTV should be contoured using CT lung windows. Although a GTV based on the CT lung windows would underestimate the gross tumor size plus microscopic extension by only 1.2 mm for the average case, the clinical target volume expansion required to cover the microscopic extension in 90% of cases could be as large as 9 mm, although considerably smaller for high-grade tumors. Fractionation significantly affects the dosimetric coverage of microscopic extension.

Pathological analysis of clinical target volume margin for radiotherapy in patients with esophageal and gastroesophageal junction carcinoma

To clarify the radiotherapy clinical target volume (CTV) margin needed for esophageal squamous-cell carcinoma (SCC) and gastroesophageal junction (GEJ) adenocarcinoma. Surgical specimens of esophageal SCC (n = 34) and GEJ adenocarcinoma (n = 32) were prospectively collected and analyzed for microscopic spread along the esophagus and GEJ both proximally and distally from gross tumor and for lymph node (LN) metastasis. For SCC, the mean microscopic spread beyond the gross tumor was 10.5 +/- 13.5 mm proximally (<30 mm in 32 of 34 cases) and 10.6 +/- 8.1 mm distally (<30 mm in 33 of 34 cases). For GEJ adenocarcinoma, the spread was 10.3 +/- 7.2 mm proximally (<30 mm in 29 of 29 cases) and 18.3 +/- 16.3 mm distally (<30 mm in 27 of 32 cases). The extent of microscopic spread of cancer was significantly associated with pathologic T stage (p = 0.012). LN metastases were observed in 12 (35%) of 34 patients with middle and lower esophageal SCC and 15 (47%) of 32 patients with GEJ adenocarcinoma. The extent of microscopic spread within esophagus (recommended CTV margin) was <30 mm in about 94% of cases of esophageal cancer, except for distal microscopic spread in GEJ adenocarcinoma, in which 50 mm was needed to cover about 94% of cases.

Dosimetric intercomparison for two Australasian clinical trials using an anthropomorphic phantom

Introduction: Many different factors can affect the accurate delivery of dose to the clinical target volume in radiotherapy. This is particularly important in the context of multicenter clinical trials where different equipment and techniques may be used for supposedly identical treatments. A dosimetric intercomparison employing an anthropomorphic phantom (level III dosimetric intercomparison) can be used to check many of the factors that could affect treatment by mimicking the radiotherapy pathway of a patient as closely as possible. Methods and Materials: An anthropomorphic phantom (ART) was taken to 18 radiotherapy centers in Australia and New Zealand and treated for two different treatment scenarios based on current clinical trials of the Trans-Tasman Radiation Oncology Group (TROG): a two-field treatment of a carcinoma of the tonsil (TROG 91.01), and a four-field prostate treatment (TROG 96.01). The dose distribution was assessed in two consecutive treatments using thermoluminescence dosimeters (TLDs) placed throughout the target volume and in “critical” structures such as the lens of the eye or the rectum. The study also included a check of absolute dose calibration in a slab phantom (level I dosimetric intercomparison). The influence of a variety of treatment parameters on the dose homogeneity in the target and the measured dose in the target and the critical organs was evaluated. Results: The dose measurements confirmed that in all participating centers the correct dose was delivered to the ICRU reference point (tonsil: 99.8 ± 2.3%; prostate: 100.9 ± 1.9% [1 SD]). Also the absolute dose calibration and the mean dose in the target volume were within the specified action levels of ± 5% for all participating centers. No influence of shielding, beam modifiers, beam weighting, treatment planning approach (CT, 2D, 3D), and type of equipment used on the dose in the target and its homogeneity could be demonstrated. However, treatment technique and energy used influenced the dose to the critical organs. It was shown that the interpretation of results could be improved by including two complementary treatment scenarios and a level I intercomparison with the level III dosimetric intercomparison. Conclusion: The study demonstrated the feasibility of a level III dosimetric intercomparison service at a cost of approximately $US 1000 per center in Australasia. It confirmed that the dose delivered by all participating centers was as intended in the two treatment scenarios chosen. While this provides reassurance to the oncology community and the general public, the service must be extended to all centers and other potentially more complex treatment scenarios. The present study has built the foundation for this by establishing a baseline and action levels and suggesting improvements in phantom design which will be included in future TROG quality assurance exercises.