Implications of Radiotherapy Utilization in Korea from 2010 to 2019.

BACKGROUND: This study was to assess the rate of radiotherapy (RT) utilization according to the modality in South Korea to identify the implications of contemporary RT patterns. METHODS: We collected information from claims and reimbursement records of the National Health Insurance Service from 2010 to 2019. We classified the location of each institution as capital (Seoul, Incheon, and Gyeonggi-do) and non-capital areas. RESULTS: The rate of RT utilization in total cancer patients nationwide was 24.5% in 2010, which consistently has increased to 36.1% in 2019 (annual increase estimate [AIE], 4.5%). There was an abrupt increase in patients receiving intensity-modulated RT (IMRT), with an AIE of 33.5%, and a steady decline in patients receiving three-dimensional conformal RT (3DCRT), with an AIE of -7.1%. The commonest RT modality was IMRT (44.5%), followed by 3DCRT and stereotactic RT (SRT) (37.2% and 13.5%) in 2019. An increasing trend of advanced RT (such as IMRT and SRT) utilization was observed regardless of the region, although the AIE in the capital areas was slightly higher than that in non-capital areas. CONCLUSION: The utilization of overall RT application and especially of advanced modalities remarkably increased from 2010 to 2019. We also found gaps in their AIEs between capital and non-capital areas. We should ensure that advanced RT is accessible to all cancer patients across South Korea.

Risk of second cancers according to radiation therapy technique and modality in prostate cancer survivors.

PURPOSE: Radiation therapy (RT) techniques for prostate cancer are evolving rapidly, but the impact of these changes on risk of second cancers, which are an uncommon but serious consequence of RT, are uncertain. We conducted a comprehensive assessment of risks of second cancer according to RT technique (>10 MV vs ≤10 MV and 3-dimensional [3D] vs 2D RT) and modality (external beam RT, brachytherapy, and combined modes) in a large cohort of prostate cancer patients. METHODS AND MATERIALS: The cohort was constructed using the Surveillance Epidemiology and End Results-Medicare database. We included cases of prostate cancer diagnosed in patients 66 to 84 years of age from 1992 to 2004 and followed through 2009. We used Poisson regression analysis to compare rates of second cancer across RT groups with adjustment for age, follow-up, chemotherapy, hormone therapy, and comorbidities. Analyses of second solid cancers were based on the number of 5-year survivors (n=38,733), and analyses of leukemia were based on number of 2-year survivors (n=52,515) to account for the minimum latency period for radiation-related cancer. RESULTS: During an average of 4.4 years' follow-up among 5-year prostate cancer survivors (2DRT = 5.5 years; 3DRT = 3.9 years; and brachytherapy = 2.7 years), 2933 second solid cancers were diagnosed. There were no significant differences in second solid cancer rates overall between 3DRT and 2DRT patients (relative risk [RR] = 1.00, 95% confidence interval [CI]: 0.91-1.09), but second rectal cancer rates were significantly lower after 3DRT (RR = 0.59, 95% CI: 0.40-0.88). Rates of second solid cancers for higher- and lower-energy RT were similar overall (RR = 0.97, 95% CI: 0.89-1.06), as were rates for site-specific cancers. There were significant reductions in colon cancer and leukemia rates in the first decade after brachytherapy compared to those after external beam RT. CONCLUSIONS: Advanced treatment planning may have reduced rectal cancer risks in prostate cancer survivors by approximately 3 cases per 1000 after 15 years. Despite concerns about the neutron doses, we did not find evidence that higher energy therapy was associated with increased second cancer risks.

Medical error analysis in dermatology according to the reports of the North Rhine Medical Association from 2004-2013.

BACKGROUND: Patient safety is a central issue of health care provision. There are various approaches geared towards improving health care provision and patient safety. By conducting a systematic retrospective error analysis, the present article aims to identify the most common complaints brought forth within the field of dermatology over a period of ten years. METHODS: The reports of the Expert Committee for Medical Malpractice Claims of the North Rhine Medical Association (from 2004 to 2013) on dermatological procedures were analyzed (n =  247 reports in the field of dermatology). RESULTS: Expert medical assessments in the field of dermatology are most frequently commissioned for nonsurgical therapies (e.g. laser therapy, phototherapy). While suspected diagnostic errors constitute the second most common reason for complaints, presumed dermatosurgery-related errors represent the least common reason for commissioning expert medical assessments. CONCLUSIONS: The most common and easily avoidable sources of medical errors include failure to take a biopsy despite suspicious clinical findings, or incorrect clinicopathological correlations resulting in deleterious effects for the patient. Furthermore, given the potential for incorrect indications and the inadequate selection of devices to be used as well as their parameter settings, laser and phototherapies harbor an increased risk in the treatment of dermatological patients. The fourth major source of error leading to complaints relates to incorrect indications as well as incorrect dosage and administration of drugs. Analysis of expert medical assessment reports on treatment errors in dermatology as well as other medical specialties is helpful and provides an opportunity to identify common sources of error and error-prone structures.

Adjuvant IMRT/XELOX radiochemotherapy improves long-term overall- and disease-free survival in advanced gastric cancer.

PURPOSE: In a retrospective analysis, adjuvant intensity-modulated radiation therapy (IMRT) combined with modern chemotherapy improved advanced gastric cancer survival rates compared to a combination of three-dimensional conformal radiation therapy (3D-CRT) and conventional chemotherapy. We report on the long-term outcomes of two consecutive patient cohorts that were treated with either IMRT and intensive chemotherapy, or 3D-CRT and conventional chemotherapy. PATIENTS AND METHODS: Between 2001 and 2008, 65 consecutive gastric cancer patients received either 3D-CRT (n = 27) or IMRT (n = 38) following tumor resection. Chemotherapy comprised predominantly 5-fluorouracil/folinic acid (5-FU/FA) in the earlier cohort and capecitabine plus oxaliplatin (XELOX) in the latter. The primary endpoints were overall survival (OS) and disease-free survival (DFS). RESULTS: Median OS times were 18 and 43 months in the 3D-CRT and IMRT groups, respectively (p = 0.0602). Actuarial 5-year OS rates were 26 and 47 %, respectively. Within the IMRT group, XELOX gave better results than 5-FU/FA in terms of OS, but this difference was not statistically significant. The primary cause of death in both groups was distant metastasis. Median DFS times were 14 and 35 months in the 3D-CRT and IMRT groups, respectively (p = 0.0693). Actuarial 5-year DFS rates were 22 and 44 %, respectively. Among patients receiving 5-FU/FA, DFS tended to be better in the IMRT group, but this was not statistically significant. A similar analysis for the XELOX group was not possible as 3D-CRT was almost never used to treat these patients. No late toxicity exceeding grade 3 or secondary tumors were observed. CONCLUSION: After a median follow-up period of over 5 years, OS and DFS were improved in the IMRT/XELOX treated patients compared to the 3D-CRT/5-FU/FA group. Long-term observation revealed no clinical indications of therapy-induced secondary tumors or renal toxicity.

Megavoltage photon beam attenuation by carbon fiber couch tops and its prediction using correction factors.

The purpose of this study was to evaluate the effect of megavoltage photon beam attenuation (PBA) by couch tops and to propose a method for correction of PBA. Four series of phantom measurements were carried out. First, PBA by the exact couch top (ECT, Varian) and Imaging Couch Top (ICT, BrainLAB) was evaluated using a water-equivalent phantom. Second, PBA by Type-S system (Med-Tec), ECT and ICT was compared with a spherical phantom. Third, percentage depth dose (PDD) after passing through ICT was measured to compare with control data of PDD. Forth, the gantry angle dependency of PBA by ICT was evaluated. Then, an equation for PBA correction was elaborated and correction factors for PBA at isocenter were obtained. Finally, this method was applied to a patient with hepatoma. PBA of perpendicular beams by ICT was 4.7% on average. With the increase in field size, the measured values became higher. PBA by ICT was greater than that by Type-S system and ECT. PBA increased significantly as the angle of incidence increased, ranging from 4.3% at 180 degrees to 11.2% at 120 degrees . Calculated doses obtained by the equation and correction factors agreed quite well with the measured doses between 120 degrees and 180 degrees of angles of incidence. Also in the patient, PBA by ICT was corrected quite well by the equation and correction factors. In conclusion, PBA and its gantry angle dependency by ICT were observed. This simple method using the equation and correction factors appeared useful to correct the isocenter dose when the PBA effect cannot be corrected by a treatment planning system.

Concurrent chemoradiotherapy in resected extrahepatic cholangiocarcinoma.

PURPOSE: Extrahepatic cholangiocarcinoma is a rare malignancy. Despite radical resection, survival remains poor, with high rates of local and distant failure. To clarify the role of radiotherapy with chemotherapy, we performed a retrospective analysis of resected patients who had undergone chemoradiotherapy. METHODS AND MATERIALS: A total of 45 patients (13 with proximal and 32 with distal disease) underwent resection plus radiotherapy (median dose, 50.4 Gy). All but 1 patient received concurrent fluoropyrimidine-based chemotherapy. The median follow-up was 30 months for all patients and 40 months for survivors. RESULTS: Of the 45 patients, 33 underwent adjuvant radiotherapy, and 12 were treated neoadjuvantly. The 5-year actuarial overall survival, disease-free survival, metastasis-free survival, and locoregional control rates were 33%, 37%, 42%, and 78%, respectively. The median survival was 34 months. No patient died perioperatively. Patient age

A measured data set for evaluating electron-beam dose algorithms.

The purpose of this work was to develop an electron-beam dose algorithm verification data set of high precision and accuracy. Phantom geometries and treatment-beam configurations used in this study were similar to those in a subset of the verification data set produced by the Electron Collaborative Working Group (ECWG). Measurement techniques and quality-control measures were utilized in developing the data set to minimize systematic errors inherent in the ECWG data set. All measurements were made in water with p-type diode detectors and using a Wellhöfer dosimetry system. The 9 and 20 MeV, 15 x 15 cm2 beams from a single linear accelerator composed the treatment beams. Measurements were made in water at 100 and 110 cm source-to-surface distances. Irregular surface measurements included a "stepped surface" and a "nose-shaped surface." Internal heterogeneity measurements were made for bone and air cavities in differing orientations. Confidence in the accuracy of the measured data set was reinforced by a comparison with Monte Carlo (MC)-calculated dose distributions. The MC-calculated dose distributions were generated using the OMEGA/BEAM code to explicitly model the accelerator and phantom geometries of the measured data set. The precision of the measured data, estimated from multiple measurements, was better than 0.5% in regions of low-dose gradients. In general, the agreement between the measured data and the MC-calculated data was within 2%. The quality of the data set was superior to that of the ECWG data set, and should allow for a more accurate evaluation of an electron beam dose algorithm. The data set will be made publicly available from the Department of Radiation Physics at The University of Texas M. D. Anderson Cancer Center.

Conformal photon-beam therapy with transverse magnetic fields: a Monte Carlo study.

This work studies the idea of using strong transverse magnetic (B) fields with high-energy photon beams to enhance dose distributions for conformal radiotherapy. EGS4 Monte Carlo code is modified to incorporate charged particle transport in B fields and is used to calculate effects of B fields on dose distributions for a variety of high-energy photon beams. Two types of hypothetical B fields, curl-free linear fields and dipole fields, are used to demonstrate the idea. The major results from the calculation for the linear B fields are: (1) strong transverse B fields (> 1 T) with high longitudinal gradients (G) (> 0.5 T/cm) can produce dramatic dose enhancement as well as dose reduction in localized regions for high-energy photon beams; (2) the magnitude of the enhancement (reduction) and the geometric extension and the location of this enhancement (reduction) depend on the strength and gradient of the B field, and photon-beam energy; (3) for a given B field, the dose enhancement generally increases with photon-beam energy; (4) for a 5 T B field with infinite longitudinal gradient (solenoidal field), up to 200% of dose enhancement and 40% of dose reduction were obtained along the central axis of a 15 MV photon beam; and (5) a 60% of dose enhancement was observed over a 2 cm depth region for the 15 MV beam when B = 5 T and G = 2.5 T/cm. These results are also observed, qualitatively, in the calculation with the dipole B fields. Calculations for a variety of B fields and beam configurations show that, by employing a well-designed B field in photon-beam radiotherapy, it is possible to achieve a significant dose enhancement within the target, while obtaining a substantial dose reduction over critical structures.