Sea-Won Lee

Spreading pattern of epidurally administered contrast medium in rabbits

Background: The aim of this study was to examine the precise spreading pattern of epidurally administered contrast medium with small increments of injection volume for determining both the exact volume of the dose required and the site of epidural injection according to different target segments of the spinal cord in a rabbit epidural model.

Hypofractionated whole breast irradiation: new standard in early breast cancer after breast-conserving surgery.

Hypofractionated whole breast irradiation (HF-WBI) has been proved effective and safe and even better for late or acute radiation toxicity for early breast cancer. Moreover, it improves patient convenience, quality of life and is expected to be advantageous in the medical care system by reducing overall cost. In this review, we examined key randomized trials of HF-WBI, focusing on adequate patient selection as suggested by the American Society of Therapeutic Radiology and Oncology (ASTRO) guideline and the radiobiologic aspects of HF-WBI in relation to its adoption into clinical settings. Further investigation to identify the current practice pattern or cost effectiveness is warranted under the national health insurance service system in Korea.

Setup Error and Effectiveness of Weekly Image-Guided Radiation Therapy of TomoDirect for Early Breast Cancer.

Purpose This study investigated setup error and effectiveness of weekly image-guided radiotherapy (IGRT) of TomoDirect for early breast cancer. Materials and Methods One hundred and fifty-one breasts of 147 consecutive patients who underwent breast conserving surgery followed by whole breast irradiation using TomoDirect in 2012 and 2013 were evaluated. All patients received weekly IGRT. The weekly setup errors from simulation to each treatment in reference to chest wall and surgical clips were measured. Random, systemic, and 3-dimensional setup errors were assessed. Extensive setup error was defined as 5 mm above the margin in any directions. Results All mean errors were within 3 mm of all directions. The mean angle of gantry shifts was 0.6°. The mean value of absolute 3-dimensional setup error was 4.67 mm. In multivariate analysis, breast size (odds ratio, 2.82; 95% confidence interval, 1.00 to 7.90) was a significant factor for extensive error. The largest significant deviation of setup error was observed in the first week of radiotherapy (p < 0.001) and the deviations gradually decreased with time. The deviation of setup error was 5.68 mm in the first week and within 5 mm after the second week. Conclusion In this study, there was a significant association between breast size and significant setup error in breast cancer patients who received TomoDirect. The largest deviation occurred in the first week of treatment. Therefore, patients with large breasts should be closely observed on every fraction and fastidious attention is required in the first fraction of IGRT.

Prospective investigation and literature review of tolerance dose on salivary glands using quantitative salivary gland scintigraphy in the intensity-modulated radiotherapy era

The purpose of this study was to prospectively evaluate the scintigraphic results on patients who undergo intensity‐modulated radiotherapy (IMRT) to investigate the tolerance doses for the salivary glands.

Lymphovascular Invasion Increases the Risk of Nodal and Distant Recurrence in Node-Negative Stage I–IIA Non-Small-Cell Lung Cancer

Objectives: Despite complete surgical resection, 30–40% of patients with stage I–IIA non-small-cell lung cancer (NSCLC) have recurrences. We aimed to elucidate the effect of lymphovascular invasion (LVI) on the prognosis and patterns of recurrence in patients with pathologically confirmed T1–2N0 NSCLC. Methods: We evaluated 381 patients who underwent complete resection and were diagnosed with pathologic T1–2N0 NSCLC between March 2000 and January 2012. Local recurrence, nodal recurrence, and distant metastasis were defined and analyzed. Results: LVI was present in 72 patients (18.9%). The 5-year disease-free survival (DFS) for all patients was 69.9%. Patients with LVI showed a significant decrease in 5-year DFS (47.3 vs. 74.4%, p < 0.001). LVI was a significant prognostic predictor in multivariate analysis (p = 0.003). The patients with LVI showed a significantly increased 5-year cumulative incidence of nodal recurrence (22.5 vs. 8.7%, p < 0.001) and distant metastasis (30.4 vs. 14.9%, p = 0.004). However, no difference was shown between the two groups in the 5-year cumulative incidence of local recurrence (p = 0.416). Conclusions: LVI is a negative prognostic factor in patients with stage I–IIA NSCLC. The presence of LVI significantly increases the risk of nodal and distant recurrence.

Treatment outcome and risk analysis for cataract after radiotherapy of localized ocular adnexal mucosa-associated lymphoid tissue (MALT) lymphoma

Purpose We retrospectively reviewed the results of radiotherapy for localized ocular adnexal MALT lymphoma (OAML) to investigate the risk factors of cataract. Methods Sixty-seven patients with stage IE OAML treated with radiotherapy at Seoul St. Mary’s Hospital from 2001 to 2016 were included. Median treatment dose was 30 Gy. Lens protection was done in 52 (76%) patients. Radiation therapy (RT) extent was as follows: superficial (82.1%), tumor mass (4.5%), and entire orbital socket (13.4%). The risk factors for symptomatic cataract were analyzed using the Cox proportional hazard model. Results Median follow-up time was 50.9 months (range, 1.9 to 149.4 months). All patients were alive at the time of analysis. There were 7 recurrences and there was no local recurrence. Median time to recurrence was 40.4 months. There were 14 cases of symptomatic cataract. Dose >30 Gy had hazard ratio of 3.47 for cataract (p = 0.026). Omitting lens protection showed hazard ratio of 4.10 (p = 0.008). conclusions RT achieves excellent local control of ocular MALT lymphoma. Consideration of RT-related factors such as lens protection and radiation dose at the stage of RT planning may reduce the risk of RT-induced cataract after radiotherapy.

Prognostic value of nodal SUV max of 18 F-FDG PET/CT in nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

Purpose To investigate the predictive role of maximum standardized uptake value (SUVmax) of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in nasopharyngeal cancer patients treated with intensity-modulated radiotherapy (IMRT). Materials and Methods Between October 2006 and April 2016, 53 patients were treated with IMRT in two institutions and their PET/CT at the time of diagnosis was reviewed. The SUVmax of their nasopharyngeal lesions and metastatic lymph nodes (LN) was recorded. IMRT was delivered using helical tomotherapy. All patients except for one were treated with concurrent chemoradiation therapy (CCRT). Correlations between SUVmax and patients’ survival and recurrence were analyzed. Results At a median follow-up time of 31.5 months (range, 3.4 to 98.7 months), the 3-year overall survival (OS) and disease-free survival (DFS) rates were 83.2% and 77.5%, respectively. In univariate analysis, patients with a higher nodal pre-treatment SUVmax (≥ 13.4) demonstrated significantly lower 3-year OS (93.1% vs. 55.5%; p = 0.003), DFS (92.7% vs. 38.5%; p < 0.001), locoregional recurrence-free survival (100% vs. 50.5%; p < 0.001), and distant metastasis-free survival (100% vs. 69.2%; p = 0.004), respectively. In multivariate analysis, high pre-treatment nodal SUVmax (≥ 13.4) was a negative prognostic factor for OS (hazard ratio [HR], 7.799; 95% confidence interval [CI], 1.506–40.397; p = 0.014) and DFS (HR, 9.392; 95% CI, 1.989–44.339; p = 0.005). conclusions High pre-treatment nodal SUVmax was an independent prognosticator of survival and disease progression in nasopharyngeal carcinoma patients treated with IMRT in our cohort. Therefore, nodal SUVmax may provide important information for identifying patients who require more aggressive treatment.

Dosimetric comparison between modulated arc therapy and static intensity modulated radiotherapy in thoracic esophageal cancer: a single institutional experience

Purpose The objective of this study was to compare dosimetric characteristics of three-dimensional conformal radiotherapy (3D-CRT) and two types of intensity-modulated radiotherapy (IMRT) which are step-and-shoot intensity modulated radiotherapy (s-IMRT) and modulated arc therapy (mARC) for thoracic esophageal cancer and analyze whether IMRT could reduce organ-at-risk (OAR) dose. Materials and Methods We performed 3D-CRT, s-IMRT, and mARC planning for ten patients with thoracic esophageal cancer. The dose-volume histogram for each plan was extracted and the mean dose and clinically significant parameters were analyzed. Results Analysis of target coverage showed that the conformity index (CI) and conformation number (CN) in mARC were superior to the other two plans (CI, p = 0.050; CN, p = 0.042). For the comparison of OAR, lung V5 was lowest in s-IMRT, followed by 3D-CRT, and mARC (p = 0.033). s-IMRT and mARC had lower values than 3D-CRT for heart V30 (p = 0.039), V40 (p = 0.040), and V50 (p = 0.032). Conclusion Effective conservation of the lung and heart in thoracic esophageal cancer could be expected when using s-IMRT. The mARC was lower in lung V10, V20, and V30 than in 3D-CRT, but could not be proven superior in lung V5. In conclusion, low-dose exposure to the lung and heart were expected to be lower in s-IMRT, reducing complications such as radiation pneumonitis or heart-related toxicities.

A Novel Prognostic Nomogram for Predicting Risks of Distant Failure in Patients with Invasive Breast Cancer Following Postoperative Adjuvant Radiotherapy

Purpose This study aimed to identify predictors for distant metastatic behavior and build a related prognostic nomogram in breast cancer. Materials and Methods A total of 1,181 patients with non-metastatic breast cancer between 2003 and 2011 were analyzed. To predict the probability of distant metastasis, a nomogram was constructed based on prognostic factors identified using a Cox proportional hazards model. Results The 7-year overall survival and 5-year post-progression survival of locoregional versus distant recurrence groups were 67.6% versus 39.1% (p=0.027) and 54.2% versus 33.5% (p=0.043), respectively. Patients who developed distant metastasis showed early and late mortality risk peaks within 3 and after 5 years of follow-up, respectively, but a broad and low risk increment was observed in other patients with locoregional relapse. In multivariate analysis of distant metastasis-free interval, age (≥ 45 years vs. < 45 years), molecular subtypes (luminal A vs. luminal B, human epidermal growth receptor 2, and triple negative), T category (T1 vs. T2-3 and T4), and N category (N0 vs. N1 and N2-3) were independently associated (p < 0.05 for all). Regarding the significant factors, a well-validated nomogram was established (concordance index, 0.812). The risk score level of patients with initial brain failure was higher than those of non-brain sites (p=0.029). Conclusion The nomogram could be useful for predicting the individual probability of distant recurrence in breast cancer. In high-risk patients based on the risk scores, more aggressive systemic therapy and closer surveillance for metastatic failure should be considered.

The Impact of Surgical Timing on Pathologic Tumor Response after Short Course and Long Course Preoperative Chemoradiation for Locally Advanced Rectal Adenocarcinoma

Purpose A pooled analysis of multi-institutional trials was performed to analyze the effect of surgical timing on tumor response by comparing short course concurrent chemoradiotherapy (CCRT) with long course CCRT followed by delayed surgery in locally advanced rectal cancer. Materials and Methods Three hundred patients with cT3-4N0-2 rectal adenocarcinoma were included. Long course patients from KROG 14-12 (n=150) were matched 1:1 to 150 short course patients from KROG 10-01 (NCT01129700) and KROG 11-02 (NCT01431599) according to stage, age, and other risk factors. The primary endpoint was to determine the interval between surgery and the last day of neoadjuvant CCRT which yields the best tumor response after the short course and long course CCRT. Downstaging was defined as ypT0-2N0M0 and pathologic complete response (ypCR) was defined as ypT0N0M0, respectively. Results Both the long and short course groups achieved lowest downstaging rates at < 6 weeks (long 20% vs. short 8%) and highest downstaging rates at 6-7 weeks (long 44% vs. short 40%). The ypCR rates were lowest at < 6 weeks (both long and short 0%) and highest at 6-7 weeks (long 21% vs. short 11%) in both the short and long course arms. The downstaging and ypCR rates of long course group gradually declined after the peak at 6-7 weeks and those of the short course group trend to constantly increase afterwards. Conclusion It is optimal to perform surgery at least 6 weeks after both the short course and long course CCRT to obtain maximal tumor regression in locally advanced rectal adenocarcinoma.