Takeshi Iinuma’s research while affiliated with National Institute of Radiological Sciences and other places

Aim: The aim of this study was to analyze the lung cancer detection rate in asymptomatic individuals by the Fluorine-18 fluorodeoxyglucose-positron emission tomography FDG-PET cancer screening program in Japan. A total of 153,775 asymptomatic individuals underwent the FDG-PET cancer screening program; the 854 cases with findings that indicated suspected lung cancer by any detection method were analyzed. Among the 854 cases, 319 were verified as lung cancer. The relative sensitivity and positive predictive value (PPV) of FDG-PET were 86.5% and 38.9% for lung cancer, respectively. The sensitivity of PET/computed tomography (CT) scanner was higher than that of dedicated PET (100.0% vs. 63.2%), indicating that CT imaging was effective for lung cancer screening. The majority of lung carcinomas detected by FDG-PET screening were UICC stage IA or IB, but detection of smaller or less invasive carcinomas was limited. The FDG-PET screening program in Japan detected lung cancer at an early stage.

Objective The aim of this study was to survey the 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) cancer screening program conducted in Japan. Methods The “FDG-PET cancer screening program” included both FDG-PET and positron emission tomography with computed tomography (PET/CT) with or without other combined screening tests that were performed for cancer screening in asymptomatic subjects. A total of 155,456 subjects who underwent the FDG-PET cancer screening program during 2006–2009 were analyzed. Results Of the 155,456 subjects, positive findings suggesting possible cancer were noted in 16,955 (10.9 %). The number of cases with detected cancer was 1,912 (1.23 % of the total screened cases, annual range 1.14–1.30 %). Of the 1,912 cases of detected cancer, positive findings on FDG-PET were present in 1,491 cases (0.96 % of the total number of screened cases). According to the results of further examinations, the true positive rate for subjects with suggested possible cancer (positive predictive value) was 32.3 % with FDG-PET. Cancers of the colon/rectum, thyroid, lung, and breast were most frequently found (396, 353, 319, and 163 cases, respectively) with high PET sensitivity (85.9, 90.7, 86.8, 84.0 %, respectively). Prostate cancer and gastric cancer (165 and 124 cases, respectively) had low PET sensitivity (37.0 and 37.9 %, respectively). The Union for International Cancer Control (UICC) clinical stage of cancer found with the FDG-PET cancer screening program was mainly Stage I. Conclusions The FDG-PET screening program in Japan has detected a variety of cancers at an early stage. However, several cancers were found in repeated FDG-PET cancer screening program, indicating the limitation of a one-time FDG-PET cancer screening program. The value of the FDG-PET cancer screening program is left to the judgment of individuals with regard to its potentials and limitations.

The aim of this study was to estimate radiation exposure and evaluate the risks and benefits of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in cancer screening. A nationwide survey of FDG-PET cancer screening was conducted in 2006, and the results were analyzed with a common index, "extension/shortening of the average life expectancy." The average estimated effective dose was 4.4 mSv (male 4.7 mSv; female 4.0 mSv) for dedicated PET and 13.5 mSv (male 14.2 mSv; female 12.8 mSv) for PET/computed tomography (CT). The risk-benefit break-even age from the viewpoint of radiation exposure was in the 40s for men and 30s for women for dedicated PET and in the 50s for men and 50s (variable injection dose) or 60s (constant injection dose) for women for PET/CT. FDG-PET cancer screening is beneficial for examinees above the break-even ages. The risks and benefits should be explained to examinees because of the larger radiation used in cancer FDG-PET screening compared with other X-ray tests.

Objective: The aim of study was to estimate the radiation exposure and to evaluate the risk and benefit for FDG-PET cancer screening. Method: A common standard, "expansion and contraction of the average of life expectancy," was used for risk-benefit analysis based on the survey of FDG-PET cancer screening in 2006. Results: The average of the estimated effective dose was 4.4 mSv (male 4.7 mSv, female 4.0 mSv) for dedicated PET, and was 13.5 mSv (male 14.2 mSv, female 12.8 mSv) for PET/CT. As a result, the risk-benefit break-even age from a viewpoint of radiation exposure was 40's for male and 30's for female for dedicated PET, and was 50's for male, and 50's (variable injected activity) or 60's (constant injected activity) for female for PET/CT. Conclusions: FDG-PET cancer screening is beneficial for examinees, depending on the age, gender, and type of examination (PET or PET/CT). However, it is necessary to explain the risk and benefit to the subjects because of larger radiation exposure than other X-ray tests used for cancer screening.

The most distinctive feature of FDG-PET cancer screening program is the ability to find various kinds of malignant neoplasms in a single test. The aim of this survey is to clarify the range and frequency of various malignant neoplasms detected by FDG-PET cancer screening performed in Japan. "FDG-PET cancer screening" was defined as FDG-PET or positron emission tomography and computed tomography (PET/CT) scan with or without other tests performed for cancer screening of healthy subjects. This survey was based on a questionnaire regarding FDG-PET cancer screening. We analyzed the situation of 9 less frequently found malignant neoplasms including malignant lymphoma, malignancy of head and neck, esophagus, hepatobiliary and gallbladder, pancreas, kidney, cervical and uterine, ovary, and bladder. The detailed information of subjects with the suspected 9 kinds of malignant neoplasms mentioned above in the FDG-PET cancer screening program was studied in a total of 1,219 cases from 212 facilities. A statistical significance between PET/CT and PET was found in relative sensitivity and PPV for renal cell cancer. Malignant lymphoma was frequently of indolent type, suspected head and neck cancers had many false-positive results, and pancreatic cancer detected in this program was often in the advanced stage even in asymptomatic subjects. The recommendation of combined screening modality to PET or PET/CT was as follows: gastric endoscopy for assessing early esophageal cancer; abdominal ultrasound for screening hepatobiliary and gallbladder cancer; pelvic magnetic resonance imaging for assessing gynecological and pelvic cancers; and the CA125 blood test for screening ovarian cancer. Delayed image was helpful depending on the type of suspected malignant neoplasm. We analyzed various types of malignant neoplasms detected by the FDG-PET cancer screening program and presented recommended combination of examinations to cover FDG-PET and PET/CT.

Unnecessary radiological examination should be avoided, particularly for children, who are more vulnerable to radiation than adults. Replacement of X-ray examination with 18F-fluoro-2-deoxy-D-glucose (18FDG) positron emission tomography/computed tomography (PET/CT) is a potential option for reduction of radiation exposure, and thus improvement in the quality of life (QOL) of patients. Therefore, this study aimed to evaluate new plans integrating 18FDG PET/CT versus current conventional imaging (CI) plans for patients with pediatric cancers. The effects of radiation exposure from the two kinds of plans were compared using shortening of the average life expectancy as an index, and the related findings and effects of radiation exposure are discussed. Effective radiation doses from CT scanning were calculated using the ImPACT CT Patient Dosimetry Calculator software. Radiation doses in different organs and tissues from radiopharmaceuticals were obtained from the International Commission on Radiological Protection (ICRP) publication 80. Shortening of average life expectancy was calculated using software in which the linear non-threshold model (LNT) by the ICRP was adopted. In current CI plans, the mean effective dose was 168.8 mSv (range 50.5-513.4 mSv) for males and 127 mSv (range 54-239.7 mSv) for females. The mean shortening of average life expectancy was 177 days (range 53.3-542 days) for males and 185 days (range 80.4-371 days) for females. In new plans, the mean effective dose was 64.1 mSv (range 54.1-84.5 mSv) for males and 68.2 mSv (range 58.1-88.0 mSv) for females. The mean shortening of life expectancy was 67.6 days (range 57.1-89.2 days) for males and 102.5 days (range 86.8-132.6 days) for females. New 18FDG PET/CT plans may relieve the patient's physical burden and contribute to improvement of the patient's QOL. These plans may also reduce medical costs because the number of examinations to be performed is reduced. Although deterministic effects are not observed in the CI plan, careful attention should be paid to other potential effects. Because the effective dose resulting from this plan is over 100 mSv, at which stochastic effects are known to occur, radiation-induced cancers may be expected.