• 대한예방의학회:학술대회논문집
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• 2005.10a
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• pp.438-438
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• 2005

• Journal of Preventive Medicine and Public Health
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• v.39 no.3
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• pp.229-234
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• 2006

Objectives: Cardiovascular disease is one of the main causes of death and morbidity in Korea. In this study, the prevalence and incidence of developing hypertension in a male-workers' cohort were investigated during 3-years follow-up with a view to find the risk factors that affected the development of hypertension. Methods: Among the 5,374 people who participated in a routine health check up, 3,852 people with normal blood pressure and who had no history of hypertension were prospectively followed up for 3 years. The classification of hypertension was based on the JNC7 report (the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure). Life style factors and underlying diseases that were related to the risk factors of hypertension were collected by using a self-report questionnaires via the internet. Results: The prevalence of hypertension was 28.3% (1,520/5,374) at the first screening (2001). It was found that the incidence in 2004 of hypertension for the follow-up subjects (3,711) who had normal blood pressure in 2001 was 7.6 per 100 person-year. Multiple logistic regression analysis of the variables related to the risk factors of hypertension was carried out. The relative risks were 1.037 (95% CI=1.022-1.053) as the age increased 1 year and 1.039 (95% CI=1.023-1.055) as the body mass index increased $1kg/m^2$. The relative risk for the prehypertensive group was 2.501 (95% CI=1.986-3.149) compared to the normotensive group. These results showed that age, body mass index and the baseline blood pressure were significantly related to the incidence of hypertension. Conclusions: The incidence of hypertension was 7.6 per 100 person-year during follow-up. It was concluded that the risk factors for developing hypertension in the short-term were age, BMI, and prehypertension; Especially, this showed that it is necessary for prehypertensives to manage their body weight and blood pressure to prevent hypertension in middle-age by modifying their life style.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.25-31
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• 2017

Purpose: The purpose of this study was to describe treatment patterns of radiotherapy (RT) for prostate cancer in Korea. Materials and Methods: A questionnaire about radiation treatment technique and principles in 2013 was sent to 83 radiation oncologists and data from 57 hospitals were collected analyzed to find patterns of RT for prostate cancer patients in Korea. Results: The number of patients with prostate cancer treated with definitive RT ranged from 1 to 72 per hospital in 2013. RT doses and target volumes increased according to risk groups but the range of radiation doses was wide (60 to 81.4 Gy) and the fraction size was diverse (1.8 to 5 Gy). Intensity-modulated radiation therapy was used for definitive treatment in 93.8% of hospitals. Hormonal therapy was integrated with radiation for intermediate (63.2%) and high risk patients (77.2%). Adjuvant RT after radical prostatectomy was performed in 46 hospitals (80.7%). Indications of adjuvant RT included positive resection margin, seminal vesicle invasion, and capsular invasion. The total dose for adjuvant RT ranged from 50 to 72 Gy in 24-39 fractions. Salvage RT was delivered with findings of consecutive elevations in prostate-specific antigen (PSA), PSA level over 0.2 ng/mL, or clinical recurrence. The total radiation doses ranged from 50 to 80 Gy with a range of 1.8 to 2.5 Gy per fraction for salvage RT. Conclusion: This nationwide patterns of care study suggests that variable radiation techniques and a diverse range of dose fractionation schemes are applied for prostate cancer treatment in Korea. Standard guidelines for RT in prostate cancer need to be developed.

• Journal of Radiation Protection and Research
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• v.12 no.2
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• pp.37-50
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• 1987

The exposure of the population in the United States to ionizing radiation has recently been evaluated by the National Council on Radiation Protection and Measurements (NCRP). This was done by constituting six organizational groups to address various phases of the work and the results of this work are summarized in this article. The article is based on the report, by the same title, which is scheduled for publication by the NCRP in September, 1987. The six organizational groups are titled Radiation Exposure from Consumer Products, Natural Background Radiation, Radiation Associated with Medical Examinations, Radiation Received by Radiation Employees, Public Exposure from Nuclear Power, and Exposure from Miscellaneous Environmental Sources. These titles are descriptive of the subject areas covered by each of these separate groups. The data evaluated are for the years 1977-1984 with the majority of the data being for the period 1980-1982. Summary information is presented and discussed for the number of people exposed to given sources, the effective dose equivalent, the average effective dose equivalent to the U.S. population, and the genetically significant dose equivalent. The average annual effective dose equivalent from all sources to the U.S. population is approximately 3.6 mSv (360 mrem). Exposures to natural sources make the largest contribution to this total. Radon and radon decay products contribute 2.0 mSv (200 mrem) whereas the other naturally occurring radionuclides contribute 1.0 mSv (100 mrem). Among man-made or enhanced sources, medical exposures make the largest additional contributions, namely 0.39 mSv (39 mrem) for diagnosis and 0.14 mSv (14 mrem) for nuclear medicine. It was not possible to evaluate exposures for therapy. Most of the other sources of population exposure, including nuclear power and consumer products, are minor. A possible exception would be the use of tobacco products. These exposures are discussed in relation to a negligible individual risk level of $10{\mu}Sv/y$ (1 mrem/y). The NCRP considers exposures below the negligible individual risk level as trivial and as such should be dismissed.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.1
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• pp.403-406
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• 2012

Mobile phones work by transmitting and receiving radio frequency microwave radiation. The radio frequency (RF) emitted by mobile phones is stronger than FM radio signal which are known to cause cancer. Though research and evidence available on the risk of cancer by mobile phones does not provide a clear and direct support that mobile phones cause cancers. Evidence does not also support an association between exposure to radio frequency and microwave radiation from mobile phones and direct effects on health. It is however clear that lack of available evidence of cancer as regards the use of mobile phone should not be interpreted as proof of absence of cancer risk, so that excessive use of mobile phones should be taken very seriously and with caution to prevent cancer.

• Radiation Oncology Journal
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• v.36 no.2
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• pp.139-146
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• 2018

Purpose: IBTR! 2.0 nomogram is web-based nomogram that predicts ipsilateral breast tumor recurrence (IBTR). We aimed to validate the IBTR! 2.0 using an external data set. Materials and Methods: The cohort consisted of 2,206 patients, who received breast conserving surgery and radiation therapy from 1992 to 2012 at our institution, where wide surgical excision is been routinely performed. Discrimination and calibration were used for assessing model performance. Patients with predicted 10-year IBTR risk based on an IBTR! 2.0 nomogram score of <3%, 3%-5%, 5%-10%, and >10% were assigned to groups 1, 2, 3, and 4, respectively. We also plotted calibration values to observe the actual IBTR rate against the nomogram-derived 10-year IBTR probabilities. Results: The median follow-up period was 73 months (range, 6 to 277 months). The area under the receiver operating characteristic curve was 0.607, showing poor accordance between the estimated and observed recurrence rate. Calibration plot confirmed that the IBTR! 2.0 nomogram predicted the 10-year IBTR risk higher than the observed IBTR rates in all groups. High discrepancies between nomogram IBTR predictions and observed IBTR rates were observed in overall risk groups. Compared with the original development dataset, our patients had fewer high grade tumors, less margin positivity, and less lymphovascular invasion, and more use of modern systemic therapies. Conclusions: IBTR! 2.0 nomogram seems to have the moderate discriminative ability with a tendency to over-estimating risk rate. Continued efforts are needed to ensure external applicability of published nomograms by validating the program using an external patient population.

• Radiation Oncology Journal
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• v.36 no.4
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• pp.285-294
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• 2018

Purpose: To determine the necessity of postmastectomy radiotherapy (PMRT) and which regions would be at risk for recurrence, we evaluated local and regional recurrence in breast cancer patients with 1-3 positive nodes and a tumor size of <5 cm. Materials and Methods: We retrospectively analyzed data of 133 female breast cancer patients with 1-3 positive nodes, and a tumor size of <5 cm who were treated with mastectomy followed by adjuvant systemic therapy between 2007 and 2016. The median follow-up period was 57 months (range, 12 to 115 months). Most patients (82.7%) were treated with axillary lymph node dissection. Adjuvant chemotherapy, endocrine therapy, and trastuzumab therapy were administered to 124 patients (93.2%), 112 (84.2%), and 33 (24.8%), respectively. The most common chemotherapy regimen was anthracycline and cyclophosphamide followed by taxane (71.4%). Results: Three patients (2.3%), 8 (6.0%), and 12 (9.0%) experienced local, regional, and distant failures, respectively. The 5-year cumulative risk of local recurrence, regional recurrence, distant metastasis, and disease-free survival was 3.1%, 8.0%, 11.7%, and 83.4%, respectively. There were no statistically significant clinicopathologic factors associated with local recurrence. Lymphovascular invasion (univariate p = 0.015 and multivariate p = 0.054) was associated with an increased risk of regional recurrence. Conclusion: Our study showed a very low local recurrence in patients with 1-3 positive nodes and tumor size of <5 cm who were treated with mastectomy and modern adjuvant systemic treatment. The PMRT volume need to be tailored for each patient's given risk for local and regional recurrence, and possible radiation-related toxicities.

• Radiation Oncology Journal
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• v.37 no.4
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• pp.254-258
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• 2019

Purpose: Deep inspiration breath hold (DIBH) is a well-established technique that enables efficient cardiac sparing in patients with left-sided breast cancer. The aim of the current study was to determine if DIBH is effective for reducing radiation exposure of of liver and other organs at risk in right breast radiotherapy (RT). Materials and Methods: Twenty patients with right-sided breast cancer were enrolled in this study. Three-dimensional conformal RT plans were generated for each patient, with two different computed tomography scans of free breathing (FB) and DIBH. Nodes were contoured according to the Radiation Therapy Oncology Group contouring guidelines. Dose-volume histograms for the target volume coverage and organs at risk were evaluated and analyzed. Results: DIBH plans showed significant reduction in mean liver dose (5.59 ± 2.07 Gy vs. 2.54 ± 1.40 Gy; p = 0.0003), V_20Gy (148.38 ± 73.05 vs. 64.19 ± 51.07 mL; p = 0.0003) and V_10Gy (195.34 ± 93.57 vs. 89.81 ± 57.28 mL; p = 0.0003) volumes compared with FB plans. Right lung doses were also significantly reduced in DIBH plans. Heart and left lung doses showed small but statistically significant improvement with application of the DIBH technique. Conclusion: We report that the use of DIBH for right-sided breast cancer significantly reduces the radiation doses to the liver, lungs, and heart.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.351-356
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• 2022

The purpose of this study was to evaluate the cancer incidence rate and provide basic data by measuring the photoneutron dose generated during intensity-modulated radiation therapy and volumetric modulated arc therapy used in radiation therapy for prostate cancer. The optically stimulated luminescence albedo neutron dosimeter for neutron measurement was placed on the Rando phantom in the abdomen and thyroid and photoneutron dose generated was measured. As a result of the study, intensity-modulated radiation therapy (7 portal) was measured to be higher than volumetric rotational radiation therapy in both abdominal and thyroid locations. When the cancer incidence rate was evaluated using the nominal risk coefficient of ICRP 103, the cancer incidence rate due to exposure to the colon and thyroid during intensity-modulated radiation therapy was 9.9 per 1,000 people, and volumetric rotational radiation therapy for 1,000 people. It was 3.5 per person. Based on the principle of ALARA (As low as reasonably archievable), it is considered to be a guideline for minimizing the exposure dose to normal organs in the establishment of a radiation treatment plan.

• Journal of Preventive Medicine and Public Health
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• v.43 no.6
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• pp.543-548
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• 2010

Objectives: The objective of this study was to calculate sample size and power in an ongoing cohort, Korea radiation effect and epidemiology cohort (KREEC). Method: Sample size calculation was performed using PASS 2002 based on Cox regression and Poisson regression models. Person-year was calculated by using data from '1993-1997 Total cancer incidence by sex and age, Seoul' and Korean statistical informative service. Results: With the assumption of relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, sample size calculation was 405 events based on a Cox regression model. When the relative risk was assumed to be 1.5 then number of events was 170. Based on a Poisson regression model, relative risk=1.3, exposure:non-exposure=1:2 and power=0.8 rendered 385 events. Relative risk of 1.5 resulted in a total of 157 events. We calculated person-years (PY) with event numbers and cancer incidence rate in the nonexposure group. Based on a Cox regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, 136 245PY was needed to secure the power. In a Poisson regression model, with relative risk=1.3, exposure:non-exposure=1:2 and power=0.8, person-year needed was 129517PY. A total of 1939 cases were identified in KREEC until December 2007. Conclusions: A retrospective power calculation in an ongoing study might be biased by the data. Prospective power calculation should be carried out based on various assumptions prior to the study.