Microscopic Extension Research Articles

Use of Standardized Uptake Value and Metabolic Tumor Volume to Predict Microscopic Extensions for Clinical Tumor Volume Delineation of Non–small-cell Lung Cancer

Our previous study suggested that the maximal standardized uptake value (SUVmax) has positive correlation with the maximal Microscopic Extensions (MicExt) for primary tumor of non–small-cell lung cancer (NSCLC). Metabolic tumor volume (MTV), a total body tumor burden, was a novel value reflected by the volume of tumor tissue demonstrating increased FDG uptake. The current analysis adds to MTV correlate to MicExt and to compare with above three factors in different tumor grade groups, respectively, in NSCLC.

9043 Computer-assisted prediction of microscopic disease extension around non-small cell lung cancer using a pathology-validated PET/CT classifier

9043 Computer-assisted prediction of microscopic disease extension around non-small cell lung cancer using a pathology-validated PET/CT classifier

Application of Robotic Stereotactic Radiotherapy to Peripheral Stage I Non-small Cell Lung Cancer with Curative Intent

Aims To determine the effectiveness of robotic stereotactic radiotherapy with image guidance and real-time respiratory tracking against early stage peripheral lung cancer. Materials and methods We treated patients with stage I non-small cell lung cancer (NSCLC) with CyberKnife ® and analysed their clinical characteristics and outcomes. All patients had co-morbid conditions that precluded lobectomy. The clinical target volume (CTV) included the gross tumour volume (GTV) and a 6 mm margin in all directions to account for microscopic extension. The planning target volume (PTV) equalled CTV + 2 mm in all directions for uncertainty. Tumour motion was tracked using a combination of Synchrony ® and Xsight ® Spine tracking methods with the aid of a single gold marker implanted in the centre of the tumour, or using the newer Xsight ® Lung method without markers for selected tumours. A 60–67.5 Gy dose was prescribed to the 60–80% isodose line (median 65%) and given in three to five fractions. Patients were followed every 3 months for a median of 27.5 months (range 24–53 months). Results Of the 67 patients with NSCLC stage IA or IB treated between January 2004 and December 2008, we report the results of a cohort of 31 with peripheral stage I tumours of 0.6–71 cm 3 volume treated between January 2004 and December 2007 with total doses between 60 and 67.5 Gy in three to five fractions. The median D max was 88.2 Gy and the median V 95 of the PTV was 99.6% or 27.9 cm 3. No grade 3 or above toxicity was encountered. Four cases of radiation pneumonitis and one case of oesophagitis were observed. In those patients whose pre- and post-treatment results were available, no change in pulmonary function tests was observed. Actuarial local control was 93.2% for 1 year and 85.8% for up to 4.5 years. One-year overall survival was 93.6% and 83.5% for up to 4.5 years, as projected by Kaplan–Meier analyses. Conclusions In this small cohort of patients with stage I peripheral NSCLC, robotic stereotactic radiotherapy seems to be a safe and obviously superior alternative to conventionally fractionated radiotherapy, with results that may be approaching those obtained with lobectomy without the associated morbidity.

Parametrial Involvement in Radical Hysterectomy Specimens for Women With Early-Stage Cervical Cancer

To estimate the incidence of parametrial involvement and to evaluate factors associated with parametrial spread in women with early-stage cervical cancer and to identify a cohort of patients at low risk for parametrial spread who may benefit from less radical surgery. We reviewed all patients who underwent radical hysterectomy and pelvic lymphadenectomy for invasive cervical cancer between 1990 and 2006. All women with squamous, adenocarcinoma, or adenosquamous disease, stage IA2-IB1, who underwent completed radical hysterectomy were included in the analysis. Normally distributed continuous variables were compared using Student's t-test for independent samples to analyze the outcome of positive or negative parametrial involvement. Three hundred fifty patients met the inclusion criteria. Overall, 27 women (7.7%) had parametrial involvement. The majority of specimens with parametrial involvement (52%) had tumor spread through direct microscopic extension. Patients with parametrial involvement were more likely to have a primary tumor size larger than 2 cm (larger than 2 cm: 14%, smaller than 2 cm: 4%, P=.001), higher histologic grade (grade 3: 12%, grades 1 and 2: 3%, P=.01), lymphovascular space invasion (positive: 12%, negative: 3%, P=.002), and metastasis to the pelvic lymph nodes (positive: 31%, negative: 4%, P<.001). One hundred twenty-five women (36%) had squamous, adenocarcinoma, or adenosquamous lesions, all grades, with primary tumor size 2 cm or smaller and no lymphovascular space invasion. In this group of patients, there was no pathologic evidence of parametrial involvement. We were able to retrospectively identify a cohort of women with early-stage cervical cancer who were at very low risk for parametrial involvement. If prospective application of these findings confirms our results, less radical surgery-such as simple hysterectomy, simple trachelectomy, or conization-with pelvic lymphadenectomy may be a reasonable therapeutic option for women with primary tumors 2 cm or smaller and no lymphovascular space invasion. III.

Segmentation automatique du volume tumoral des cancers pulmonaires non à petites cellules sur la 18F-FDG TEP-TDM en vue d’un traitement par radiothérapie

Purpose Radiotherapy belongs to the treatment of certain stages of non-small cell lung cancer. It requires a preliminary delimitation of the tumour by the radiotherapist with a contouring of the tumour on the CT but this method does not take into account the biological characteristics of the target and remains dependent on the operator. To optimize the irradiation volume, several teams created methods of automatic segmentation on the PET-CT, still under evaluation. Material and methods We undertook a retrospective study on 17 patients to evaluate the difference between obtained volumes by CT delimitation with those deduced by three algorithms of automatic segmentation based on PET-CT (Black et al., Nestle et al. and Tylski et al.). A confrontation with histological tumoral volume has been carried on in case of surgery. Results On average, the three methods under evaluated tumoral volume compared to the CT of 8% for Nestle et al., 22% for Black et al. and 30% for Tylski et al., but these results hide disparities, which tended to decrease with a grouping of tumours by size. The most important differences were due to heterogeneous uptake of FDG (necrosis, spicules, atelectasis). Conclusion The method of Black et al. was the most discrepant one. For tumours less than 45 cm 3, Nestle's et al. algorithm tends to overestimate the CT volume and thus makes it possible to integrate safety margins into final volume (microscopic extension). The method of Tylski et al. presents an interesting approach (correction of partial volume effect) but still requires developments because it under evaluates too much the target volume.

Defining the Clinical Target Volume for Bladder Cancer Radiotherapy Treatment Planning

There are currently no data for the expansion margin required to define the clinical target volume (CTV) around bladder tumors. This information is particularly relevant when perivesical soft tissue changes are seen on the planning scan. While this appearance may reflect extravesical extension (EVE), it may also be an artifact of previous transurethral resection (TUR). Eighty patients with muscle-invasive bladder cancer who had undergone radical cystectomy were studied. All patients underwent preoperative TUR and staging computed tomography (CT) scans. The presence and extent of tumor growth beyond the outer bladder wall was measured radiologically and histopathologically. Forty one (51%) patients had histologically confirmed tumor extension into perivesical fat. The median and mean extensions beyond the outer bladder wall were 1.7 and 3.1 mm, respectively. Thirty five (44%) patients had EVE, as seen on CT scans. The sensitivity and specificity of CT scans for EVE were 56% and 79%, respectively. False-positive results were infrequent and not affected by either the timing or the amount of tissue resected at TUR. CT scans consistently tended to overestimate the extent of EVE. Tumor size and the presence of either lymphovascular invasion or squamoid differentiation predict a greater extent of EVE. In patients with radiological evidence of extravesical disease, the CTV should comprise the outer bladder wall plus a 10-mm margin. In patients with no evidence of extravesical disease on CT scans, the CTV should be restricted to the outer bladder wall plus a 6-mm margin. These recommendations would encompass microscopic disease extension in 90% of cases.

Extension of ovarian tissue into the infundibulopelvic ligament beyond visual margins

Objective The purpose of our study was to identify microscopic margins of the ovary and possible extension of the ovarian tissue beyond visual margins into the infundibulopelvic (IP) tissue to formulate recommendations for adequate salpingo-oophorectomy. Methods An observational study was conducted with thirty female patients who underwent bilateral salpingo-oophorectomy (BSO) as part of their procedure at Bethesda North Hospital between September 2007 and May 2008. Results Thirty patients underwent BSO as part of their primary procedure. Two ovaries were excluded from the study because of multiple adhesions to the pelvic wall and distortion of the IP ligaments resulting in fifty-eight ovaries accepted for study. Microscopic extension of the ovarian stroma into IP ligament beyond gross visual margins was found in eight ovaries (13.8%), five left ovaries and three right ovaries. The range of the extension was from 0.2 cm to 1.4 cm (four ovaries 0.2 cm, one 0.4 cm, two 0.8 cm and one 1.4 cm). Conclusion Our study demonstrates that ovarian stroma can extend beyond grossly visual margins. To prevent residual ovarian tissue following oophorectomy surgeons need to ligate the IP ligament at or more than 2 cm proximal to the visual ovarian margins. Similar surgical principals need to be applied during oophorectomy by abdominal, laparoscopic and vaginal approach.

Mass in the Neck After Radiation Exposure from Chernobyl Disaster

Mass in the Neck After Radiation Exposure from Chernobyl Disaster

Dose Coverage Beyond the Gross Tumor Volume for Various Stereotactic Body Radiotherapy Planning Techniques Reporting Similar Control Rates for Stage I Non–Small-Cell Lung Cancer

To investigate the dose falloff region for various stereotactic body radiotherapy (SBRT) planning techniques used in the treatment of Stage I non-small-cell lung cancer reporting similar control rates. The SBRT plans were constructed on five patient data sets using seven different planning regimens. These regimens varied in the number of beams, number of fractions, prescription target, and prescribed dose used. For each case all regimens were planned using a common gross tumor volume (GTV). To compare dose falloff for the various regimens, resulting physical dose grids were converted into normalized total dose (NTD) grids. Furthermore, to determine the potential coverage of microscopic extension of the various regimens minimal peripheral NTD (NTD-MP(100)) were calculated and plotted as a function of incremental volume expansions of the GTV. Average values for NTD-MP(100) varied over a range of 174 Gy at the GTV periphery, but this range fell to 10 Gy at a distance of 14 mm from the GTV. Of 35 plans, 23 resulted in potential microscopic extension coverage of 78% to 95%. Averages for five of seven regimens fell within the range of 80% to 85%. Results were negligibly affected when intrafraction motion effects were accounted for. Although average NTD-MP(100) varied dramatically at the GTV, periphery values became similar at a distance of 14 mm from the GTV. With the exception of two, potential coverage of microscopic extension was similar for all planning techniques, with averages falling within a 5% range.

A Comparative Study on Radiology and Pathology Target Volume in Primary Liver Cancer

The incidence of primary liver cancer (PLC) in China is high. Three dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) are currently being explored as a new radiation technique for the treatment of localized primary liver cancer and hepatic metastases. Using this technique, tumor control probability and patient's survival rate have been improved, while the radiation-induced liver disease reduced. Therefore, it is important to know how much margin is needed to ensure accurate radiation dose delivery. However, there is no report about the accurate margin in the radiation therapy of PLC. In this study, according to the contrast of gross tumor volume (GTV) of primary liver cancer (PLC) between radiology and pathology, we tried to define the correlation of GTV between radiology and pathology, and define the degree of local microscopic extension (ME) of PLC, so to define the margin of CTV precisely. At the process of target volume definition of 3D-CRT and IMRT, the GTV of radiology could direct the definition of CTV precisely. To provide accordance how much margin would be enough from GTV to CTV of 3D-CRT and IMRT. From February 2006 to December 2006, 28 PLC patients after surgical resection were studied. All patients had a CT scan of the liver before surgery and had routine pathology examination after surgery. We measured the tumor sizes at X axis (lateral direction), Y axis (ventrodorsal direction), and Z (cranicaudal direction) axis on CT, respectively. After operation, we did pathology examination. We measured the tumor sizes at X, Y, and Z axis and the degree of ME at X, Y, and Z axis, respectively. Without taking into account the value of ME, there were almost agreement about GTV between radiology and pathology at 3-dimensions. The mean value of ME was 0.6 mm for PLC. To take into account 95% of the ME, a margin of 2.3 mm must be chosen for PLC. There was a correlation of about GTV between radiology and pathology. At the process of target volume definition of 3D-CRT and IMRT, we could use the GTV of radiology to replace the GTV of pathology. To cover 95% of the ME, the margin from GTV to CTV must be increased to 2.3 mm.

Use of Standardized Uptake Value (SUV) to Predict Tumor Grade for Radiotherapy Planning of Lung Adenocarcinoma

We previously have observed that with an increase in lung adenocarcinoma grade, there is less mean microscopic extension beyond gross tumor due to a higher % solid growth and lower % bronchioalveolar component. The purpose of this study is to identify various histopathological and clinical characteristics that correlate with maximum primary tumor 18-FDG uptake at pre-treatment evaluation for lung adenocarcinoma.

SU‐GG‐J‐112: Integration and Verification of 3T Magnetic Resonance Spectroscopic Imaging in Radiation Therapy Treatment Planning

Purpose: The purpose of this work is to test the feasibility of MRSI integration into brain tumor RT planning using a custom‐built MRSI head phantom as well as a case study. Method and Materials: A special MRSI head phantom was constructed with spatially well‐defined tube inserts. Each tube contains different pre‐determined concentrations of metabolite solutions that mimic different degrees of brain tumor burden and were immersed in a background solution that emulate normal brain metabolite levels. The 3D MRSI data were acquired on a Siemens 3T TRIO TIM scanner using PRESS (point resolved spectroscopy) sequence with TE/TR: 135/1510 ms, 16×16×8 matrix, FOV: 16×16×8 resulting in MRSI voxel size of 10×10×10 mm3. Registration of MRSI (gray scale DICOM) data with planning CT and creation of metabolite‐derived target contours were performed on Pinnacle treatment planning system. Target contours created using MRSI‐derived tumor metabolic abnormalities were compared with those created based on morphological (T2 and T1 contrast weighted) MRI scans. Results: The CT‐MR (T1) registration accuracy was found to be within 1 mm, with no spatial distortion during MRSI. Registration errors were found in the TPS due to field‐of‐view size and origin difference between studies. These were corrected using a simple algorithm to determine the translation. Re‐scaled MRSI pixel values allowed automated segmentation of metabolic ratios and were consistent with those identified on the control console of the MRI scanner. When applied to a clinical case, a 42 cc (or 58%) reduction in the treated volume of the PTV was possible, assuming the CNI ratio of 2.5 included all microscopic extension of disease requiring the boost dose. Conclusion: MRSI derived functional information can be incorporated into RT planning for brain tumors well within the registration tolerance limits of current planning process.

Radical Cystectomy for Carcinoma of the Bladder: 2,720 Consecutive Cases 5 Years Later

We performed a critical analysis of the results of radical cystectomy for invasive bladder carcinoma treated at 1 center. Between 1970 and 2000, 2,090 men and 630 women with invasive bladder cancer were treated with 1-stage radical cystectomy and urinary diversion. Followup ranged from 0 to 34.2 years with a mean of 5.5 +/- 5.7. Survival data were correlated to patient and tumor characteristics using univariate and multivariate analysis. Postoperative mortality was 2.6%. Squamous tumors accounted for 49.4% of cases, transitional cell carcinoma for 36.4% and adenocarcinoma for 9.6%. Regional lymph nodes were involved in 20.4% of cases. The 5 and 10-year disease-free survival rates were 55.5% and 50.03%, respectively. Evidence was provided that tumor stage, histological grade and lymph node status are the only independent variables which affect survival probability. Contemporary cystectomy can be performed with minimal mortality. Radical cystectomy for organ confined disease is followed by good therapeutic results and enhances the possibilities for functional restoration. With stage progression there is a stepwise reduction in survival probability. The radical operation can provide disease-free survival for an important subgroup of node positive cases (27.3%). Additional therapy is needed to improve the oncological outcome for advanced locoregional disease.

Computational study of anisotropic epitaxial recrystallization in 4H-SiC

Two nano-sized amorphous layers were created within a crystalline cell to study anisotropicexpitaxial recrystallization using molecular dynamics (MD) methods in 4H-SiC. Bothamorphous layers were created with the normal of the amorphous–crystalline (a–c)interfaces along the [0001] direction, but one had a microscopic extension along the [] direction, i.e. the dimension along the [] direction is much larger than that along the [] direction (Ix model), and the other had a microscopic extension along the [] direction (Iy model). The amorphous layer within theIx model can be completely recrystallized at 2000 K within an achievable simulation time, and therecrystallization is driven by a step-regrowth mechanism. On the other hand, the nucleationand growth of secondary ordered phases are observed at high temperatures in theIy model. The temperature for recrystallization of the amorphous layer into high-quality4H-SiC is estimated to be below 1500 K. Compared with other models, it is found that theregrowth rates and recrystallization mechanisms depend strongly on the orientation of4H-SiC, whereas the activation energy spectra for recrystallization processes areindependent of any specific polytypic structure, with activation energies ranging from 0.8 to1.7 eV.

Macroscopic, but not microscopic, perivesical fat invasion at radical cystectomy is an adverse predictor of recurrence and survival

To examine whether the presence of microscopic (pT3a) or macroscopic (pT3b) disease worsens the prognosis relative to pT2 disease at radical cystectomy, as the prognostic significance of pT3a vs pT3b perivesical fat invasion (pT3) is controversial. In all, 242 patients with pT3 disease (pT3a in 88, pT3b in 121) had radical cystectomy and bilateral pelvic lymphadenectomy for transitional cell carcinoma of the urinary bladder; they were compared with 172 who had organ-confined muscle-invasive disease (pT2). For the analyses we used univariable and multivariable Cox regression models of recurrence and cancer-specific survival, adjusted for age, tumour grade, lymphovascular invasion and the presence of lymph node metastases. In multivariable analyses, microscopic perivesical fat extension (pT3a) was not associated with higher recurrence (P = 0.3) or the mortality rate (P = 0.06) vs pT2 disease. Conversely, the presence of deep perivesical fat extension (pT3b) was associated with 1.8 times the rate of recurrence (P = 0.002) and with twice the rate of death (P = 0.001) vs pT2 disease. These findings imply that a detailed assessment of the cystectomy specimen for the presence of microscopic perivesical fat invasion might not be necessary, as the presence of pT3a disease has no strong effect on recurrence or mortality. Moreover, patients with pT3a disease might not require more aggressive therapy than their counterparts with pT2 disease. However, further validation of our data is required.

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.

WE‐D‐BRA‐03: Cyberknife Experience

Purpose: The purpose of this presentation is to show in selected case studies where differential dose planning is used in Cyberknife treatments, and which challenges are associated with each approach. Method and Materials: Three case studies were selected to demonstrate different situations were differential dose planning would be used in Cyberknife SRS. Case1: Multiple, anatomically close cranial lesions of varying sizes. As experience with Gammaknife SRS has shown, the risk of complications in treating brain metastasis is correlated with dose and lesion size. Lesions larger than 2 cm in diameter are typically treated with a lower dose. In the situation were multiple lesions of different size are located closely together in the brain, creating separate treatment plans on the Cyberknife would lead to longer treatment times, higher whole‐body dose due to scatter and leakage, and difficulty to asses multiple plan dose overlays.Case 2: The second situation involved mostly head and neck cancers where the GTV and CTV are treated to different doses as a boost after conventional IMRT treatments. Typically, the GTV encompasses the PET positive areas. Around the GTV, a CTV enclosing the microscopic extension of the disease as determined by the physician based on the case history.Case 3: Unusual cases. A patient with pituitary adenoma was also diagnosed with Graves disease. Because of the proximity of the lesion and the orbital muscles affected by Graves disease, the tumor and orbital muscles were treated at the same time with different dose. Results: All three categories could be planned to the physicians' satisfaction. In case 1 patients, attention has to be paid to minimizing the dose to the healthy brain between the lesions. This can be achieved by using tuning structures or tuning shells around the tumors. In Case 2, the limiting factor is the dose fall‐off outside the GTV. A fraction of the CTV will be treated at a higher dose than planned. In case 3, the combined planning of the Graves disease and the pituitary adenoma achieved good dose sparing of the optic apparatus. Conclusion: The Cyberknife software is very flexible and allows relatively easy planning for complex situations.

Determining optimal clinical target volume margins on the basis of microscopic extracapsular extension of metastatic nodes in patients with non–small-cell lung cancer

To determine the optimal clinical target volume (CTV) margins around the nodal gross tumor volume (GTV) in non-small-cell lung cancer (NSCLC) patients by assessing microscopic tumor extension beyond regional lymph node capsules. The incidence of nodal extracapsular extension (ECE) and relationship with nodal size were reviewed in 243 patients. Histologic sections of dissected regional lymph nodes up to 30 mm in size were examined to measure the extent of microscopic ECE. We determined the distribution of cases according to extent of ECE and the relationships between ECE extent and lymph node size, regional nodal disease extent, histologic type, and degree of differentiation. The nodal ECE was seen in 41.6% of patients (101/243) and 33.4% of lymph nodes (214/640), and the incidence correlated to larger lymph node size positively. The extent of ECE was 0.7 mm in mean (range, 0-12.0 mm) and <or=3 mm in 95% of the nodes. Positive correlations were found between extent of ECE and larger lymph node size (>or=20 mm vs. 10-19 mm or <10 mm, p = 0.005), advanced nodal stage (N2 vs. N1, p = 0.046), and moderate or poor (vs. good or unknown) nodal differentiation (p = 0.002). ECE did not differ significantly by histologic type or nodal station. The incidence of ECE related to lymph node size, and ECE extent related to lymph node size, stage, and differentiation. It may be reasonable to recommend 3-mm CTV margins for pathologic lymph nodes <20 mm and more generous margins for lymph nodes >or=20 mm.

Extensive Sampling Changes T-Staging of Infiltrating Lobular Carcinoma of Breast: A Comparative Study of Gross versus Microscopic Tumor Sizes

Infiltrating lobular carcinoma represents 7-10% of all invasive breast cancers. The greatest diameter of the tumors in the surgical specimens is required for an accurate T-staging. Tumors with dimension of zero cm, >0 to < or =2 cm, >2 to < or =5 cm, and >5 cm are staged as T0, T1, T2, and T3, respectively. A retrospective study on the specimens was performed on the specimens of 74 cases with infiltrating lobular carcinoma at the UCLA Medical Center from 2003 to 2005. The patients' ages ranged from 38 to 95 years. Specimens were from lumpectomy and mastectomy procedures on 36 and 38 patients, respectively. The specimens were divided in four groups according to the gross T-stages. Microscopic measurement of the tumors was carried out within each of the four groups for restaging purposes. Resizing of tumors was performed by marking the microscopic tumor extensions and compiling the measurements. In group 1, all 26 gross T0 tumors changed to T1 (69%), T2 (19%), and T3 (12%) after microscopic restaging. In group 2, 50% of the 26 gross T1 tumors became T2 (35%) and T3 (15%). In group 3, 9 (50%) of the T2 tumors changed to T3 microscopically. All 7 specimens (100%) in group 4 remained as T3. The results show that the gross measurements alone may underestimate 40-50% of the tumor T-stages. Therefore, the T-stages of the tumors with a gross size of 5 cm or less may change by microscopic resizing after an extensive sampling of the specimen.

2484: The Study on Correlation Between F-18 FDG PET/CT Standard Uptake Value and Clinical Target Volume Definition in Radiotherapy for Non-Small Cell Lung Cancer

2484: The Study on Correlation Between F-18 FDG PET/CT Standard Uptake Value and Clinical Target Volume Definition in Radiotherapy for Non-Small Cell Lung Cancer