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Sang-Wook Lee

Publications and source records attributed to Sang-Wook Lee.

13 recordsLinked to original sources
PubMed2005

Preoperative concurrent radiotherapy with capecitabine before total mesorectal excision in locally advanced rectal cancer.

PURPOSE: Capecitabine is an attractive radiosensitizer which can be tumor specific. This study was undertaken to evaluate the toxicity and efficacy of oral capecitabine when used with preoperative radiation therapy. METHODS AND MATERIALS: We conducted a prospective Phase II trial to assess the pathologic response, sphincter preservation effect, and acute toxicity of preoperative chemoradiation (CRT) in locally advanced (uT3-4/N +) but resectable adenocarcinoma of the lower two-thirds of the rectum. The radiation dose was 50 Gy over 5 weeks (46 Gy to whole pelvis + 4 Gy boost), and capecitabine was administered daily at a dose of 1650 mg/m(2) during the entire course of radiation therapy. Surgery was performed with standardized total mesorectal excision 4 to 6 weeks after completion of CRT and followed by four cycles of capecitabine (2500 mg/m(2)/day for 14 days). RESULTS: Ninety-five patients were entered into this study; their median age was 55 (range, 31-75 years). Ninety (95%) patients completed preoperative CRT as planned, and complete resection was achieved in 92 of 94 resected cases (98%). Downstaging rate was 71% (56/79) on endorectal ultrasonography, and it was 76% (71/94) on pathology finding. No tumor cell was observed in the specimens of 11 patients (12%). Among the 54 whose tumor was located within 5 cm from the anal verge, 40 patients (74%) underwent sphincter-preserving procedures. Elevation of the distal tumor margin from the anal verge by preoperative CRT was 0.8 +/- 1.3 cm. Grade 3 toxicities were rare (diarrhea in 3% and neutropenia in 1%). CONCLUSION: Preoperative CRT using capecitabine achieved encouraging rates of tumor downstaging and sphincter preservation with a low toxicity profile.

Adolescent↗
PubMed2005

Expressions of Ku70 and DNA-PKcs as prognostic indicators of local control in nasopharyngeal carcinoma.

PURPOSE: The objective of this study was to determine whether the expressions of the two components of DNA-dependent protein kinase, Ku70 and DNA-protein kinase catalytic subunit (DNA-PKcs), influence the response to radiotherapy (RT) and outcome of treatment of nondisseminated nasopharyngeal carcinoma (NPC) in patients who received definitive RT. METHODS AND MATERIALS: Sixty-six patients with NPC who were treated with radiotherapy alone or with concurrent chemotherapy between June 1995 and December 2001 were divided into groups based on the levels of immunoreactivity for Ku70 and DNA-PKcs in pretreatment biopsy specimens. The overexpression of Ku70 or DNA-PKcs groups included patients whose biopsy specimens showed at least 50% immunopositive tumor cells; patients in which less than 50% of the tumor cells in the biopsy tissues were immunopositive were placed in the low Ku70 and DNA-PKcs groups. The immunoreactivities for Ku70 and DNA-PKcs were retrospectively compared with the sensitivity of the tumor to radiation and the patterns of therapy failure. Univariate analyses were performed to determine the prognostic factors that influenced locoregional control of NPC. RESULTS: The 5-year locoregional control rate was significantly higher in the low Ku70 group (Ku-) (85%) than in the high Ku70 group (Ku+) (42%) (p = 0.0042). However, there were no differences in the metastases-free survival rates between the 2 groups (Ku70+, 82%; Ku70- 78%; p = 0.8672). Univariate analysis indicated that the overexpression of Ku70 surpassed other well-known predictive clinicopathologic parameters as an independent prognostic factor for locoregional control. Eighteen of 22 patients who had locoregional recurrences of the tumor displayed an overexpression of Ku70. No significant association was found between the level of DNA-PKcs expression and the clinical outcome. CONCLUSIONS: Our data suggest that the level of Ku70 expression can be used as a molecular marker to predict the response to RT and the locoregional control after RT and concurrent chemotherapy in patients with nondisseminated NPC.

Adult↗
PubMed2005

FDG-PET in the prediction of pathologic response after neoadjuvant chemoradiotherapy in locally advanced, resectable esophageal cancer.

PURPOSE: To assess the efficacy of 18Fluorodeoxyglucose-positron emission tomography (FDG-PET) for predicting a pathologic response in locally advanced esophageal cancer after neoadjuvant chemoradiotherapy. METHODS AND MATERIALS: All enrolled patients were treated with neoadjuvant chemoradiotherapy followed by esophagectomy and underwent two FDG-PET scans, before and after neoadjuvant chemoradiotherapy. We compared the results of the preoperative FDG-PET scans with the pathologic results. RESULTS: From July 2001 to July 2004, 32 patients (29 men and 3 women) were enrolled in this study. Pathologic complete response (pCR) in the esophagus was achieved in 21 of 32 patients (66%). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in the primary tumors of the preoperative FDG-PET were 27%, 95%, 75%, and 71%, respectively. In regional lymph nodes, these values were 16%, 98%, 36%, and 93%, respectively. The mean standardized uptake value (SUV) of primary tumors was initially 5.6 +/- 3.6 and changed to 1.5 +/- 1.3 after neoadjuvant chemoradiotherapy (p < 0.05). If analysis of metabolic response (SUV decrease, DeltaSUV) was limited to initially highly metabolic primary tumors (SUV > or =4.0), pathologic response was correlated with metabolic response (p = 0.006). CONCLUSIONS: This study suggested that the pathologic response of an initially highly metabolic tumor after neoadjuvant chemoradiotherapy could be correlated with the metabolic response, and FDG-PET can provide additional information on tumor response to chemoradiotherapy.

Aged↗
PubMed2005

Phase II study of radiotherapy with three-dimensional conformal boost concurrent with paclitaxel and cisplatin for Stage IIIB non-small-cell lung cancer.

PURPOSE: To evaluate the efficacy and toxicity of concurrent chemoradiotherapy with paclitaxel/cisplatin for Stage IIIB locally advanced non-small-cell lung cancer (NSCLC). METHODS AND MATERIALS: Radiotherapy was administered to a total dose of 70.2 Gy (daily fraction of 1.8 Gy, 5 days/wk), over an 8-week period, combined with chemotherapy. The chemotherapy consisted of weekly 40 mg/m2 of paclitaxel plus 20 mg/m2 of cisplatin for 8 consecutive weeks. All patients received three-dimensional conformal radiotherapy (3D-CRT), based on computed tomography simulated planning after 41.4 Gy. The median follow-up period of survivors was 24 months. RESULTS: Between January 2000 and October 2002, 135 patients with a median age of 60 years were enrolled and analyzed in this prospective trial. The overall response rate was 75% including 2 cases of complete response. The major patterns of failure were local failure and distant metastasis. The 2-year overall and progression-free survival rates were 37% and 18%, respectively. The median overall and progression-free survival times were 17 months and 9 months, respectively. Hematologic toxicity >Grade 2 was observed in 19% of patients and severe non-hematologic toxicity was infrequent. CONCLUSIONS: Three-dimensional conformal radiotherapy, combined with paclitaxel and cisplatin chemotherapy, was associated with a satisfactory outcome with manageable toxicity. Further investigations are needed to improve the local control.

Adenocarcinoma↗
PubMed2005

Development and evaluation of an optimization-based model for power-grip posture prediction.

An optimization-based model for power-grip posture prediction was proposed. The model was based on the premise that the hand prehensile configuration in a power grip best conforms to the object shape. This premise was embodied by an optimization procedure that minimized the sum of distances from the finger joints to the object surface. The model was evaluated against data from an experiment that measured the grasp postures of 28 subjects having diverse anthropometry. The intra- and inter-person variabilities in grip postures were empirically assessed and used as benchmark values for model evaluation. The evaluation showed that the root-mean-square (RMS) values of angle differences between the predicted and measured postures had a 13.7 degrees grand mean (across all joints, subjects, and two cylindrical handles grasped), whereas the RMS values of the inter- and intra-person variabilities in measured postures had grand means of 13.0 degrees and 4.4 degrees , respectively. The model can be readily generalized to the prediction of postures in power-grasping objects of different shapes, and adapted for testing alternative prehensile strategies or performance criteria.

Adult↗
PubMed2004

Correlation between dispersion properties of TiO2 colloidal sols and photoelectric characteristics of TiO2 films.

TiO2 film for use as dye-sensitized solar cell was prepared using the TiO2 colloidal sols (unpeptized sol and peptized sol). The optical properties and photocurrent-voltage characteristics of the resultant films were investigated. The optical transmittance of TiO2 thin film prepared from the peptized colloidal sol was over 90%, while that of TiO2 film from the unpeptized sol was under 80%. The TiO2 photoelectrode prepared from the peptized colloidal sol showed low photoelectric conversion efficiency (eta), 1.30%, whereas the efficiency of photoelectrode from the unpeptized sol was 2.21%. The high optical transmittance and low conversion efficiency of TiO2 film from the peptized sol are discussed in terms of dense microstructure due to the drying nature of well-dispersed colloidal sol.

Colloids↗
PubMed2004

Clinical relevance of three subtypes of primary sinonasal lymphoma characterized by immunophenotypic analysis.

BACKGROUND: The purpose of this study was to investigate the clinical relevance of subtypes categorized by immunophenotypic analysis in primary sinonasal lymphomas. METHODS: Eighty patients with localized non-Hodgkin's lymphoma involving the nasal cavity and/or paranasal sinuses were divided into three subtypes on the basis of their immunohistochemical findings: (A) B-cell lymphoma (n = 19), (B) T-cell lymphoma (n = 27), and (C) natural killer (NK)/T-cell lymphoma (n = 34). The clinicopathologic profiles, immunophenotypic data, patterns of treatment failure, and survival data among the three patient groups were retrospectively compared. RESULTS: The nasal cavity was the predominant site of involvement in T-cell and NK/T-cell lymphoma, whereas sinus involvement without nasal disease was common in B-cell lymphoma. Systemic B symptoms were frequently observed in NK/T-cell lymphoma. Almost all patients with NK/T-cell lymphoma showed a strong association with the Epstein-Barr virus by in situ hybridization studies. Sixty-five patients (81%) patients achieved complete remission after initial treatment, but 36 (55%) of these subsequently experienced treatment failure. Although there were no significant differences in locoregional failure rates among the patients of the three groups, distant failure was far more common in B-cell or NK/T-cell lymphoma than in T-cell lymphoma (p =.005). Most B-cell lymphoma cases showed a predilection for sites of systemic failure in the nodal and extranodal sites below the diaphragm, such as the paraaortic lymph nodes or the gastrointestinal (GI) tract, whereas patients with NK/T-cell lymphoma showed an increased risk of systemic dissemination to the skin, testes, or GI tract, including the development of hemophagocytic syndrome. The 5-year actuarial and disease-free survival rates for all patients were 57% and 51%, respectively. Of the three subtypes of primary sinonasal lymphomas, T-cell lymphoma seemed to carry the most favorable prognosis and NK/T-cell lymphoma the worst. (The 5-year actuarial survival rate was 57% for B-cell lymphoma, 80% for T-cell lymphoma, 37% for NK/T-cell lymphoma; p =.02, log-rank.) By univariate and multivariate analyses, immunophenotype was identified as the most important prognostic factor. CONCLUSIONS: Our data indicate that the three subtypes of primary sinonasal lymphomas classified by immunohistochemical studies exhibit different clinical profiles, different patterns of failure, and different treatment outcomes. Given these observations, it is concluded that the recognition of these distinct subsets, diagnosed on the basis of immunophenotypic study, is very important and clinically relevant in predicting their potential behavior and prognosis.

Adolescent↗
PubMed2004

Lack of correlation between P-glycoprotein and chemotherapy resistance in nasal NK/T-cell lymphomas.

Thirty patients with nasal natural killer (NK)/T-cell lymphoma, who underwent systemic chemotherapy with or without involved-field radiotherapy between 1993 and 1998, were retrospectively reviewed to determine the clinical significance of P-glycoprotein immunohistochemically identified in tumor specimens. Eighty percent of previously untreated patients expressed P-glycoprotein. According to P-glycoprotein immunoreactivity, all patients with nasal NK/T-cell lymphoma were divided into 2 groups; (a) P-glycoprotein-negative group (N = 6) and (b) P-glycoprotein-positive group (N = 24). There was no significant difference in clinical profiles between both groups. Regardless of the P-glycoprotein expressions, Epstein-Barr virus genomes were almost identically detected in patients of the 2 groups. Contrary to our expectations, however, P-glycoprotein expressions were not found to be a strong predictor of chemotherapy resistance. Although 2 (33%) of 6 P-glycoprotein-negative patients and 10 (42%) of the 24 P-glycoprotein-positive patients showed a favorable response to systemic chemotherapy, 4 (67%) of 6 P-glycoprotein-negative patients did not achieve complete response (CR) to chemotherapy, which led to an early death, whereas 4 (17%) of the 24 P-glycoprotein-positive patients achieved CR to chemotherapy despite positive P-glycoprotein immunoreactivity. Overall, there were no significant differences in either CR rate or the response rate of patients in the two groups. Overall 5-year actuarial survival and disease-free survival for all patients were 44% and 47%, respectively, but no differences in survival rates were observed between 2 groups. (5-year actuarial survival rate: 33% for the P-glycoprotein-negative, 50% for the P-glycoprotein-positive) (P = 0.7093, log-rank). On univariate and multivariate analyses, P-glycoprotein expressions by immunohistochemical study were not found to be an important prognostic factor. Given these observations, we conclude that the molecular mechanisms of resistance to chemotherapy in nasal NK/T-cell lymphoma patients are not entirely dependent on P-glycoprotein, and that other complex mechanisms of drug action and resistance may be likely to be involved.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Determining finger segmental centers of rotation in flexion-extension based on surface marker measurement.

This paper describes the development of a novel algorithm for deriving finger segmental center of rotation (COR) locations during flexion-extension from measured surface marker motions in vivo. The algorithm employs an optimization routine minimizing the time-variance of the internal link lengths, and incorporates an empirically quantifiable relationship between the local movement of a surface marker around a joint (termed "surface marker excursion") and the joint flexion-extension. The latter relationship constrains and simplifies the optimization routine to make it computationally tractable. To empirically investigate this relationship and test the proposed algorithm, an experiment was conducted, in which hand cylinder-grasping movements were performed by 24 subjects (12 males and 12 females). Spherical retro-reflective markers were placed at various surface landmarks on the dorsal aspect of each subject's right (grasping) hand, and were measured during the movements by an opto-electronic system. Analysis of experimental data revealed a highly linear relationship between the "surface marker excursion" and the marker-defined flexion-extension angle: the average R(2) in linear regression ranged from 0.89 to 0.97. The algorithm successfully determined the CORs of the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints of digits 2-5 during measured motions. The derived CORs appeared plausible as examined in terms of the physical locations relative to surface marker trajectories and the congruency across different joints and individuals.

Adult↗
PubMed2003

Theoretical hydraulic consequences of vein graft taper.

OBJECTIVE: Internal diameter is a strong predictor of patency of infrainguinal vein grafts. However, most vein grafts are tapered, with variable diameter along their length. It is unknown which diameter is most important in determining graft resistive properties, that is, its mean diameter, minimum diameter, or some geometric combination thereof. The purpose of this analysis was to examine the hydraulic consequences of vein graft tapering, with longitudinal impedance (Z(L)), a conduit-specific measure of pulsatile resistance along straight rigid tubes. METHODS: Proximal and distal graft pressure, pressure gradient (DeltaP), and blood flow (Q) were measured intraoperatively in a 100 cm bypass graft and digitally recorded for 10 seconds at 200 Hz. With the Womersley solution for fully developed fluid flow in a rigid tube, a series of DeltaP waveforms were generated for graft diameters ranging from 1.2 to 8.2 mm. With an axisymmetric form of the Navier-Stokes equations, a second series of DeltaP waveforms were computed for grafts with long smooth symmetric tapers ranging from 0% to 90%, with geometric mean diameter of 3.2, 4.2, and 5.2 mm (%Taper = 100 x [proximal diameter - distal diameter]/proximal diameter). For each set of DeltaP and Q, Z(L) was calculated as DeltaP/Q, plotted over a range of 8 Hz, and integrated over 4 Hz to yield integral Z(L). RESULTS: The architecture of the calculated DeltaP and Z(L) waveforms closely approximated their measured counterparts, validating the method. As expected, Z(L) was highly diameter-dependent in a nonlinear fashion. With a clinically relevant boundary of less than 50 x 10(3) dyne/cm(5) as "acceptable," the minimum acceptable diameter of nontapered 100 cm bypass conduits was 4.3 mm. Analysis of graft taper revealed that small amounts of taper in large conduits were well-tolerated. For example, introduction of 32% taper in a 5.2 mm graft (6.2 mm --> 4.2 mm) caused only an 8% increase in integral Z(L) (from 32 to 35 x 10(3) dyne/cm(5)). More pronounced taper in smaller conduits rendered them unacceptable. For example, 53% taper of a 4.2 mm graft (5.7 mm --> 2.7 mm) created a conduit with integral Z(L) of 70 x 10(3) dyne/cm(5), well above the acceptable limit. The relationship between Z(L) and percent taper was nonlinear and strongly dependent on mean diameter. CONCLUSIONS: The relationship between Z(L) and diameter in vein grafts is nonlinear; thus Z(L) increases rapidly in conduits smaller than 4 mm. Tapered vein grafts behave hydraulically like nontapered grafts, provided their geometric mean is greater than 4 mm and their degree of taper is less than 40%. Tapered veins are satisfactory conduits for long-segment bypass grafts, provided their mean diameter is acceptable.

Hemodynamics↗
PubMed2002

Intensity modulation technique using the complementary boost-fields for ethmoid sinus cancer.

PURPOSE: To explore a static intensity-modulated radiation therapy (IMRT) technique of a more homogeneous isodose distribution to an irregular-shaped tumour of the ethmoid sinus, with concomitantly sparing the adjacent critical normal organs including the orbit. METHODS AND MATERIALS: We conducted a static IMRT technique adding 2 or smaller complementary boost-fields to the underdosed volume in the PTV, which resulted from complete blocking of the orbits in all coplanar or non-coplanar main ports of the standard 3-D CRT. The standard 3-D CRT plans (Plan A) and IMRT plans adding complementary boost fields (Plan B) were established for 10 patients with ethmoid sinus cancer. Two sets of different plans for each patient were compared using isodose distribution, dose statistics, and dose volume histogram (DVH) of the planning target volume (PTV) and also using dose statistics and DVH of the adjacent critical structures. RESULTS: The IMRT plans adding 2 or more complementary boost-fields (Plan B) for each patient demonstrated better coverage and improved dose homogeneity of the PTV compared to the standard 3-D CRT plan (Plan A). Moreover, the radiation doses to adjacent normal tissue organs, such as the orbits, optic nerves, brain stem and optic chiasm were similarly spared in both plans. CONCLUSION: With concomitantly sparing the surrounding visual pathway structures, our IMRT technique using the complementary boost-fields was quantitatively better than current standard 3-D CRT technique with respect to the dose homogeneity within the PTV. Therefore, we believe that our technique, though still not ideal, is thorough enough to be used routinely in treatment of ethmoid sinus tumour.

Adult↗
PubMed2002

Role of radiotherapy for primary orbital lymphoma.

To define the role of radiation therapy of primary orbital lymphoma, a retrospective analysis was undertaken for 18 patients with primary orbital lymphoma who were treated with curative radiotherapy between 1984 and 1995. The histology was found to be low grade lymphoma in 11 patients, intermediate grade in 7. All patients were of Ann Arbor stage IE, but bilateral involvement of the orbit was observed in 3 patients (16.6%). Anatomical subsites involved were the retrobulbar, eyelid, and conjunctiva in eight, five, and four patients, respectively. The median radiation dose was 30 Gy ranging from 20 Gy to 50 Gy. Twelve of 18 patients received a radiation dose of 30 Gy or less. To properly protect the lens during irradiation, the contact lens blocks were used for nine patients with conjunctival and eyelid tumor or the hanging eye bar blocks were applied for eight patients with retrobulbar tumor. Chemotherapy was given for seven patients with intermediate-grade malignant lymphoma. Two patients had been treated by surgery before referral.

Adolescent↗