• Journal of Radiation Protection and Research
• /
• v.38 no.4
• /
• pp.214-227
• /
• 2013

Computed tomographic scan as a screening procedures in asymptomatic individuals has seen a steady increase with the introduction of multiple-raw detector CT scanners. This report provides a brief review of the current controversy surrounding CT cancer screening, with a focus on the radiation induced cancer risks and clinical efficacy. 1. A large study of patients at high risk of lung cancer(the National Lung Screening Trial[NLST]) showed that CT screening reduced cancer deaths by 20%(1.33% in those screened compared with 1.67% in those not screened). The rate of positive screening tests was 24.2% and 96.4% of the positive screening results in the low-dose CT group were false-positive. Radiation induced lung cancer risk was estimated the most important in screening population because ERR of radiation induced lung cancer does not show the decrease with increasing age and synergistic connection between smoking and radiation risk. Therefore, the radiation risk may be on the same order of magnitude as the benefit observed in the NLST. Optimal screening strategy remain uncertain, CT lung cancer screening is not yet ready for implementation. 2. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but significantly less sensitive and specific for smaller lesions and disadvantageous for subsequent therapeutic optical colonoscopy if polyps are detected. The average effective dose from CT colonography was estimated 8-10 $mS{\nu}$, which could be a significant dose if administered routinely within the population over many years. CT colonography should a) achieve at least 90% sensitivity and specificity in the size category from 6 and 10 mm, b) offer non-cathartic bowl preparation and c) be optimized and standardized CT parameters if it is to be used for mass screening. 3. There is little evidence that demonstrates, for whole-body scanning, the benefit outweighs the detriment. This test found large portion of patient(86~90.8%) had at least one abnormal finding, whereas only 2% were estimated to have clinically significant disease. Annual scans from ages 45 to 75 years would accrue an estimated lifetime cancer mortality risk of 1.9%. There is no group within the medical community that recommends whole-body CT. No good studies indicate the accuracy of screening CT, at this time. The benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established. These areas need further research. Therefore wild screening should be avoided.

• Journal of Digestive Cancer Research
• /
• v.4 no.1
• /
• pp.17-20
• /
• 2016

Colorectal cancer is the 2^nd most common cancer in men, and the 3^rd most common cancer in women in Korea. This incidence has been increasing steadily since the data analysis began in 1999. Guidelines from many countries including Korea recommend annual or biennial fecal occult blood test as a national colorectal cancer screening program, however, colonoscopy, stool DNA test, double contrast barium enema, and sigmoidoscopy are recommended in some countries. I will summarize the Korean National Screening Guideline for colorectal cancer revised by multi-society expert committee in Korea last year. They recommend annual or biennial fecal immunochemical test between 45 and 80 year-old asymptomatic average risk people. Selective use of colonoscopy is recommended, taking into consideration of individual preference and the risk of colorectal cancer. There is no evidence for the risks or benefits of double contrast barium enema or computed tomographic colonography for colorectal cancer screening.