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Background Screening is one of the effective interventions for the reduction of colorectal cancer mortality. Though the Japanese government recommends faecal occult blood test and colonoscopy as a follow-up examination following a diagnosis, both participation rates have not been so high and the national mortality rate has not shown a clear decreasing trend. Methods Microsimulation models simulate the life histories of a large population of individuals under various scenarios. In this study, we applied a microsimulation model to estimate the reduction of colorectal cancer mortality based on screening scenarios. Results The effect of reducing the age-standardized mortality rate for colorectal cancer was estimated at 9.4% for men and 6.0% for women under the scenario which calls for 50% participation in faecal occult blood test and 90% participation of follow-up examination. This scenario corresponds to the goal setting for screening in the third-term of the Basic Plan to Promote Cancer Control Programs in Japan. Conclusions Our microsimulation model was found to be useful in estimating the mortality reduction effect of cancer control policy. Such modelling techniques can be utilized to develop effective and optimal cancer control programs.

The easy-to-calculate gender, age, and lung physiology (GAP) model shows good predictive and discriminative performance in the prognosis of idiopathic pulmonary fibrosis (IPF). However, the GAP model was not effective in predicting the prognosis accurately in previous Japanese and Korean IPF cohort studies. Therefore, we developed a modified GAP model for the East-Asian populations by weighing the GAP variables. The validity of the modified GAP model was subsequently evaluated in East-Asian IPF patients.The derivation cohort comprised 326 patients with IPF. Weights of the variables were adjusted on the basis of coefficients derived from Cox regression models. The total points were distributed to the three stages of the disease so that the number of patients included in each stage was appropriate. The validity of the modified model was analyzed in another Japanese cohort of 117 patients with IPF and a nationwide cohort of Korean patients with IPF.Predicted survival rates differed significantly in the derivation cohort using the modified GAP model for each stage of IPF (log-rank test: stage I vs. stage II, p 0.001; stage II vs. stage III, p 0.001). Model performance improved according to Harrell's C-index (at three years: 0.696 in the original GAP model to 0.738 in the modified model). The performance of the modified model was validated in the Japanese validation and Korean national cohorts.Our modification of the original GAP model showed improved performance in East-Asian IPF patient populations.

OBJECTIVE To assess the limitations of single-energy metal artifact reduction algorithm in the oral cavity and evaluate the availability of a solution by setting the patient in a lateral position (LP) with the use of a gantry tilt (GT). METHODS We analyzed 88 patients with dental metals retrospectively in study 1, and 74 patients prospectively in study 2. Patients were classified: metal I with dental metals in 1 region, metal II in 2 regions, and metal III in 3 regions. Patients underwent neck computed tomography examinations in a supine position (SP) in study 1, and 2 positions, an LP with a GT and an SP, in study 2. All images were reconstructed with this algorithm. Image quality was scored using a 4-point scale: 1 = severe artifact, 2 = moderate artifact, 3 = slight artifact, 4 = no artifact. The scores were compared between metal I, metal II, and metal III using the Mann-Whitney U test in study 1, and between an LP with a GT and an SP using the Wilcoxon signed ranks test in study 2. RESULTS The scores outside the dental arch were significantly higher in metal I than in metal II and metal III (3.0 ± 0.6 vs 2.3 ± 0.5 vs 2.2 ± 0.4; P < 0.0001 for metal I vs metal II and for metal I vs metal III) and significantly higher in an LP with a GT than an SP (3.2 ± 0.4 vs 2.3 ± 0.4; P < 0.0001). CONCLUSIONS Single-energy metal artifact reduction algorithm could reduce metal artifacts adequately in patients with dental metals in 1 region, but not in 2 or more regions. However, even for the latter, combination of this algorithm and an LP with a GT could further improve the image quality.

Information of prefectural cancer incidence in Japan is an important resource to plan an effective regional cancer control program. In order to obtain accurate prefectural cancer incidence, we have to adjust for both of completeness of regional cancer registries and regional dispersion, simultaneously, Then, we developed a hierarchal Bayes model with a completeness adjustment by using the relation between MI ratio (mortality divided by incidence) and proportion of death certificate notified among incidence. Prefectural cancer incidence is estimated with the 95% credible interval, which suggests that the national MI ratio should be 0.386 if the registry were complete. Because cancer behavior has a variation depending on prefecture, such accurate incidence must contribute to plan and assess regional cancer control program.

Background Patients undergoing hematopoietic stem cell transplantation (HSCT) frequently have HHV-6 reactivation typically during the early phase following HSCT. The long-term clinical complications and prognosis, however, remain unclear. Methods Between September 2010 and October 2012, whole blood samples from 105 patients collected weekly from prior to 6 weeks after HSCT underwent multiplex polymerase chain reaction (PCR) to screen for viral DNA, followed by real-time PCR for quantitative estimation. In 48 patients, only HHV-6 was detected in at least one sample. In 30 patients, no viral DNA was detected. Long-term clinical records were reviewed in March 2016. All 48 HHV-6-positive patients, and 24 patients in whom no viral DNA detected, were followed up. Results Median maximum HHV-6 DNA load in the blood of the HHV-6 reactivation group (n = 48) was 11 800 copies/μg peripheral blood leukocyte DNA (range, 52-310 000 000). Hemophagocytic syndrome (HPS) was diagnosed in two subjects with HHV-6 reactivation. Acute graft-versus-host disease (GVHD) developed more frequently in patients with HHV-6 reactivation than in patients without viral reactivation (P = 0.002), but there was no difference in incidence of chronic GVHD. There was no difference in engraftment of neutrophils and platelets between groups. There was also no difference in overall survival between groups. Onset of HPS, however, was associated with lower overall survival (P = 0.009). Conclusions Human herpesvirus 6 reactivation was associated with acute GVHD, but not with chronic GVHD, engraftment or overall survival. Onset of HPS, however, predicts lower overall survival.

Objectives To prevent the onset of lifestyle-related diseases associated with metabolic syndrome (MetS) in Japan, research into the development of a useful screening method is strongly desired. We developed a new screening questionnaire (JAMRISC) utilizing a logistic regression model and evaluated its ability to predict the development of MetS, type 2 diabetes and other lifestyle-related diseases in Japanese populace. Methods JAMRISC questionnaire was sent to 1,850 individuals in Rumoi, a small city in Hokkaido. We received a total of 1,054 valid responses. To maximize the target individuals accurately diagnosed with MetS, logistic regression analysis was used to generate a unique metabolic syndrome score calculation formula as taking into consideration the clinical relevance of each question item as individual coefficients. Results The results of our comparative research utilizing both JAMRISC and Finnish Diabetes Risk Score (FINDRISC) questionnaires revealed the usefulness of JAMRISC for its ability to detect risks for MetS, pre-MetS, diabetes, and pre-diabetes. Study of disease risk detection via JAMRISC questionnaire targeting the 4283 residents of Rumoi indicated a high detection rate for pre-MetS (98.8 %), MetS (94.2 %), pre-diabetes (85.1 %) and type 2 diabetes (94.9 %). In addition, JAMRISC was useful not only as a MetS risk score test, but also as a screening tool for diagnosing insulin resistance. Conclusions JAMRISC questionnaire is a useful instrument for the detection of early risk of not only MetS and type 2 diabetes but also insulin resistance.

Background: Together with such high-quality approaches as randomized controlled trials and large-scale cohort studies, simulation models are often employed to evaluate the effect of cancer screening methods and decide on their appropriateness. This study aimed to evaluate all effects of gastric cancer screening that have been assessed using simulation models, including cost-effectiveness, mortality reduction, and early-stage detection. Methods: We performed a systematic review using PubMed and Web of Science. We evaluated the effect of screening related to cost, such as incremental cost-effectiveness and incremental cost-effectiveness ratios; we also separately assessed effects other than cost, such as quality-adjusted life-years, number of deaths prevented, life-years saved, relative risk of mortality from gastric cancer, life expectancy, and incidence reduction. The methods targeted for evaluation were Helicobacter pylori testing or endoscopy. Results: We identified 19 studies dealing with simulation models in gastric cancer screenings: 14 examined H. pylori screening and 7 focused on endoscopy. Among those studies, two assessed both H. pylori and endoscopy screening. Most of the studies adopted a Markov model, and all the studies evaluated cost-effectiveness. Of the 14 H. pylori screening studies, 13 demonstrated cost-effectiveness and 11 also showed good results other than cost-effectiveness, such as extension of life-years and increase in early-stage detection. In three of the five endoscopy studies, the target population was patients; all five studies obtained good results for cost-effectiveness and four observed good results other than for cost-effectiveness. Conclusions: In this study, we showed that the H. pylori screening test was cost-effective in terms of simulation model investigations. However, the H. pylori screening test should not ordinarily be recommended since there is insufficient evidence that it reduces gastric cancer mortality. In Japan, simulation modeling should be employed to plan for cancer control, and the appropriate use of simulation models should be examined for future use.

Background Cancer mortality is increasing with the aging of the population in Japan. Cancer information obtained through feasible methods is therefore becoming the basis for planning effective cancer control programs. There are three time-related factors affecting cancer mortality, of which the cohort effect is one. Past descriptive epidemiologic studies suggest that the cohort effect is not negligible in cancer mortality. Methods In this paper, we develop a statistical method for automatically detecting a cohort effect and assessing its statistical significance for cancer mortality data using a varying coefficient model. Results The proposed method was applied to liver and lung cancer mortality data on Japanese men for illustration. Our method detected significant positive or negative cohort effects. The relative risk was 1.54 for liver cancer mortality in the cohort born around 1934 and 0.83 for lung cancer in the cohort born around 1939. Conclusions Cohort effects detected using the proposed method agree well with previous descriptive epidemiologic findings. In addition, the proposed method is expected to be sensitive enough to detect smaller, previously undetected birth cohort effects.

The purpose of this study was to estimate the uncertainty in the dose distribution for the 125I source STM1251, as measured with a radiophotoluminescent glass rod dosimeter and calculated using the Monte Carlo code EGS5 in geometry that included the source structure reported by Kirov et al. This was performed at a range of positions in and on a water phantom 18 cm in diameter and 16 cm in length. Some dosimetry positions were so close to the surface that the backscatter margin was insufficient for photons. Consequently, the combined standard uncertainty (CSU) at the coverage factor k of 1 was 11.0–11.2% for the measurement and 1.8–3.6% for the calculation. The calculation successfully reproduced the measured dose distribution within 13%, with CSU at k ≤ 1.6 (P > 0.3). Dose distributions were then compared with those for the 125I source Oncoseed 6711. Our results supported the American Association of Physicists in Medicine Task Group No. 43 Updated Protocol (TG43U1) formalism, in which STM1251 dose distributions were more penetrating than those of Oncoseed 6711. This trend was also observed in the region near the phantom surface lacking the equilibrium radiation scatter conditions. In this region, the difference between the TG43U1 formalism and the measurement and calculation performed in the present study was not significant (P > 0.3) for either of the source models. Selection of the source model based on the treatment plans according to the TG43U1 formalism will be practical.

This study aims to demonstrate the feasibility of a method for estimating the strength of a moving brachytherapy source during implantation in a patient. Experiments were performed under the same conditions as in the actual treatment, except for one point that the source was not implanted into a patient. The brachytherapy source selected for this study was 125I with an air kerma strength of 0.332 U (μGym2h−1), and the detector used was a plastic scintillator with dimensions of 10 cm × 5 cm × 5 cm. A calibration factor to convert the counting rate of the detector to the source strength was measured and then the accuracy of the proposed method was investigated for a manually driven source. The accuracy was found to be under 10% when the shielding effect of additional needles for implantation at other positions was corrected, and about 30% when the shielding was not corrected. Even without shielding correction, the proposed method can detect dead/dropped source, implantation of a source with the wrong strength, and a mistake in the number of the sources implanted. Furthermore, when the correction was applied, the achieved accuracy came close to within 7% required to find the Oncoseed 6711 (125I seed with unintended strength among the commercially supplied values of 0.392, 0.462 and 0.533 U).

This study sought to demonstrate the feasibility of estimating the source strength during implantation in brachytherapy. The requirement for measuring the strengths of the linked sources was investigated. The utilized sources were (125)I with air kerma strengths of 8.38-8.63 U (μGy m(2) h(-1)). Measurements were performed with a plastic scintillator (80 mm × 50 mm × 20 mm in thickness). For a source-to-source distance of 10.5 mm and at source speeds of up to 200 mm s(-1), a counting time of 10 ms and a detector-to-needle distance of 5 mm were found to be the appropriate measurement conditions. The combined standard uncertainty (CSU) with the coverage factor of 1 (k = 1) was ∼15% when using a grid to decrease the interference by the neighboring sources. Without the grid, the CSU (k = 1) was ∼5%, and an 8% overestimation due to the neighboring sources was found to potentially cause additional uncertainty. In order to improve the accuracy in estimating source strength, it is recommended that the measurment conditions should be optimized by considering the tradeoff between the overestimation due to the neighboring sources and the intensity of the measured value, which influences the random error.

A thyroid ultrasound examination programme has been conducted in Fukushima Prefecture, Japan, after the nuclear disaster in 2011. Although remarkably high prevalence of thyroid cancer was observed, no relevant quantitative evaluation was conducted. We calculated the observed/expected (O/E) ratio of thyroid cancer prevalence for the residents aged ≤20 years. Observed prevalence was the number of thyroid cancer cases detected by the programme through the end of April 2015. Expected prevalence was calculated as cumulative incidence by a life-table method using the national estimates of thyroid cancer incidence rate in 2001-10 (prior to the disaster) and the population of Fukushima Prefecture. The underlying assumption was that there was neither nuclear accident nor screening intervention. The observed and estimated prevalence of thyroid cancer among residents aged ≤20 years was 160.1 and 5.2, respectively, giving an O/E ratio of 30.8 [95% confidence interval (CI): 26.2, 35.9]. When the recent increasing trend in thyroid cancer was considered, the overall O/E ratio was 22.2 (95% CI: 18.9, 25.9). The cumulative number of thyroid cancer deaths in Fukushima Prefecture, estimated with the same method (annual average in 2009-13), was 0.6 under age 40. Combined with the existing knowledge about radiation effect on thyroid cancer, our descriptive analysis suggests the possibility of overdiagnosis. Evaluation including individual-level analysis is required to further clarify the contribution of underlying factors.

The post-implantation dosimetry for brachytherapy using Monte Carlo calculation by EGS5 code combined with the source strength regression was investigated with respect to its validity. In this method, the source strength for the EGS5 calculation was adjusted with the regression, so that the calculation would reproduce the dose monitored with the glass rod dosimeters (GRDs) on a water phantom. The experiments were performed, simulating the case where one of two (125)I sources of Oncoseed 6711 was lacking strength by 4-48%. As a result, the calculation without regression was in agreement with the GRD measurement within 26-62%. In this case, the shortage in strength of a source was neglected. By the regression, in order to reflect the strength shortage, the agreement was improved up to 17-24%. This agreement was also comparable with accuracy of the dose calculation for single source geometry reported previously. These results suggest the validity of the dosimetry method proposed in this study.

The aim of this study is to demonstrate the feasibility of estimating the strength of the moving radiation source during patient implantation. The requirement for the counting time was investigated by comparing the results of the measurements for the static source with those for the source moving at 2, 5, 10 and 20 cm s(-1). The utilized source was (125)I with an air-kerma strength of 0.432 U (μGym(2)h(-1)). The detector utilized was a plastic scintillation detector (8 cm × 5 cm × 2 cm in thickness) set at 8 cm away from the needle to guide the source. Experiments were conducted in order to determine the most desirable counting time. Analysis using the maximum of the measured values while the source passed through the needle indicated that the results for the moving source increased more than those for the static source as the counting time decreased. The combined standard uncertainty, with the coverage factor of 1, was within 4% at the counting time of 100 ms. This investigation supported the feasibility of the method proposed for estimating the source strength during the implantation procedure, regardless of the source speed. The method proposed is a potential option for reducing the risk of accidental replacements of sources with those of incorrect strengths.

Growth models are in general constructed by some kind of mathematical function, so-called “growth function”. Since there are several possible growth functions, the first task for the growth analysis is to select the most suitable growth function for the target data among candidates. In this paper, three statistical procedures are presented and compared on the basis of the information criterion for the purpose of selecting a growth function. A demonstrative example is provided to show how the three statistical procedures differ and select different growth functions for the same growth data, and how differently the amount of carbon sequestrated in a forest stand is affected by the selected growth function.

In the present article, we consider the variable selection problem in Poisson regression models. Akaike's information criterion (AIC) is the most commonly applied criterion for selecting variables. However, the bias of the AIC cannot be ignored, especially in small samples. We herein propose a new bias-corrected version of the AIC that is constructed by stochastic expansion of the maximum likelihood estimator. The proposed information criterion can reduce the bias of the AIC from O(n−1) to O(n−2). The results of numerical investigations indicate that the proposed criterion is better than the AIC.

We consider fourth order quasilinear ordinary differential equations. Firstly, we classify positive solutions into four types according to their asymptotic properties. Then we derive existence theorems of positive solutions belonging to each type. Using these results, we can obtain an oscillation criterion, which is our main objective. Moreover, applying such criteria for ordinary differential equations to binary elliptic systems, we establish nonexistence theorems for positive solutions.

PURPOSE The aim of this study was to develop a dose calculation method which is applicable to the interseed attenuation and the geometry lacking the equilibrium radiation scatter conditions in brachytherapy. METHODS The dose obtained from measurement with a radiophotoluminescent glass rod dosimeter (GRD) was compared to the dose calculated with the Monte Carlo (MC) code "EGS5," using the 125I source structure detailed in by Kennedy et al. The GRDs were irradiated with 125I Oncoseed 6711 in a human head phantom. The phantom was a cylinder made of 2 mm thick PMMA with a diameter of 18 cm and length of 16 cm. Some of the GRD positions were so close to the phantom surface that the backscatter margin was less than 5 cm, insufficient for photons. RESULTS The EGS5 simulations were found to reproduce the relative dose distributions as measured with the GRDs to within 25% uncertainty in the geometry lacking the equilibrium radiation scatter conditions. The absolute value of the GRD measurement agreed with the American Association of Physicist in Medicine Task Group No 43 Updated Protocol (AAPM-TG43U1) formalism to within 3% of the reference point (r = 1 cm, theta = 90 degrees), where the TG43U1 is especially reliable because of the abundant data accumulation in composing the formalism. The factor to normalize the measured or calculated dose to the TG43U1 estimate at the reference point was evaluated to be 0.97 for the GRD measurement and 1.8 for the MC calculation, which uses the integration of the apparent activity with the time as the amount of disintegration during the irradiation. Also, F(r,theta) and g(r) estimated by this calculation method were consistent with those proposed in the TG43U1. CONCLUSIONS The results of this investigation support the validity of both the MC calculation method and GRD measurement in this study as well as the TG-43U1 formalism. Also, this calculation is applicable to interseed attenuation and the geometry lacking the equilibrium radiation scatter.

This paper deals with a bias correction of Akaike's information criterion (AIC) for selecting variables in multivariate normal linear regression models when the true distribution of observation is an unknown non-normal distribution. It is well known that the bias of AIC is , and there are a number of the first-order bias-corrected AICs which improve the bias to , where is the sample size. A new information criterion is proposed by slightly adjusting the first-order bias-corrected AIC. Although the adjustment is achieved by merely using constant coefficients, the bias of the new criterion is reduced to . Then, a variance of the new criterion is also improved. Through numerical experiments, we verify that our criterion is superior to others. The Canadian Journal of Statistics 39: 126–146; 2011 © 2011 Statistical Society of Canada

Background Much effort has been expended on interpreting the mechanism of influenza epidemics, so as to better predict them. In addition to the obvious annual cycle of influenza epidemics, longer-term incidence patterns are present. These so-called interepidemic periods have long been a focus of epidemiology. However, there has been less investigation of the interepidemic period of influenza epidemics. In the present study, we used spectral analysis of influenza morbidity records to indentify the interepidemic period of influenza epidemics in Japan. Methods We used time series data of the monthly incidence of influenza in Japan from January 1948 through December 1998. To evaluate the incidence data, we conducted maximum entropy method (MEM) spectral analysis, which is useful in investigating the periodicities of shorter time series, such as that of the incidence data used in the present study. We also conducted a segment time series analysis and obtained a 3-dimensional spectral array. Results Based on the results of power spectral density (PSD) obtained from MEM spectral analysis, we identified 3 periodic modes as the interepidemic periods of the incidence data. Segment time series analysis revealed that the amount of amplitude of the interepidemic periods increased during the occurrence of influenza pandemics and decreased when vaccine programs were introduced. Conclusions The findings suggest that the temporal behavior of the interepidemic periods of influenza epidemics is correlated with the magnitude of cross-reactive immune responses.

The Japan Cancer Surveillance Research Group estimated the cancer incidence in 2005 as part of the Monitoring of Cancer Incidence in Japan (MCIJ) project, on the basis of data collected from 12 of 30 population-based cancer registries. The total number of incidences in Japan for 2005 was estimated as 646,802 (C00-C96). The leading cancer site was the stomach for men and the breast for women. Age-standardized incidence rates remained almost the same level as the previous 2 years.

The Japan Cancer Surveillance Research Group estimated the cancer incidence in 2004 as part of the Monitoring of Cancer Incidence in Japan (MCIJ) project, on the basis of data collected from 14 of 31 population-based cancer registries. The total number of incidences in Japan for 2004 was estimated as 623,275 (C00-C96). The leading cancer site according to the crude and age-standardized incidence rates was the stomach for men and breast for women. The apparent increase in age-standardized incidence rates in 2003 was calmed down in 2004.

SUMMARYMeasles is regarded as a disease that can be eliminated by vaccination; however, disease epidemics still occur in Wuhan, China. This study explored the effect of measles control programmes on the periodic structure of disease epidemics in Wuhan. The monthly reported measles incidence from 1953 to 2008 was divided into pre-vaccine range (1953–1965) and post-vaccine range (1966–2008). For the incidence in each range, spectral analysis was conducted and power spectral density (PSD) was obtained. In PSD for the pre-vaccine range, the most dominant spectral line was observed at a 2·0-year period, as in the case of Japan. It was confirmed that spectral lines of periodic modes longer than a 1-year cycle of the incidence rates behave in response to the introduction of measles control programmes. The investigation of periodic structures of measles epidemics will contribute to effective measles control programmes in Wuhan.

In this paper we consider positive unbounded solutions of second order quasilinear ordinary differential equations. Our objective is to determine the asymptotic forms of unbounded solutions. An application to exterior Dirichlet problems is also given.

In this paper we consider positive solutions of second order quasilinear ordinary differential equations with singular nonlinearities. We obtain asymptotic equivalence theorems for asymptotically superlinear solutions and decaying solutions. By using these theorems, exact asymptotic forms of such solutions are determined. Furthermore, we can establish the uniqueness of decaying solutions as an application of our results.

Asymptotic forms are determined for positive solutions which are called weakly increasing solutions to quasilinear ordinary differential equations.

To evaluate the usefulness of the signal intensity ratio (SIR) of the optic nerve to the white matter (WM) on short tau inversion recovery (STIR) images to diagnose acute optic neuritis (AON). The 405 consecutive patients with suspected orbital diseases underwent orbital magnetic resonance imaging (MRI) using a 3-T scanner between June 2008 and August 2011. Among them, 108 optic nerves (33 AON and 75 control) were retrospectively analysed. The averaged SIR (SIRave) and maximum SIR (SIRmax) were defined as the averaged signal intensity (SI) of the optic nerve divided by that of WM, and the maximum SI of the optic nerve divided by averaged SI of WM, respectively. These values were compared between AON and control using the Mann–Whitney U test. A P

Background The present study aimed to elucidate the changing patterns of smoking among successive birth cohorts in Japan. Methods Birth-cohort-specific smoking prevalence was estimated for birth cohorts born from 1900 to 1952, using data pooled from four prospective studies (242,330 men and 274,075 women), and for birth cohorts born from 1925 to 1977, using National Nutrition Survey data. Results For men, two peaks were observed in smoking prevalence, in the 1925 and late-1950s birth cohorts, while a trough was observed for the 1938 birth cohort. For women, ever smoking prevalence was lowest among the 1930s birth cohorts. After the female 1940s birth cohorts, no peak was observed until the end of our observations, the 1970s birth cohorts. Although Japanese women have historically tended to start smoking at later ages, recently, smoking habits have widely expanded among females in young birth cohorts. Conclusions Smoking trends in Japanese men and women vary by birth cohorts. Smoking cessation should continue to be strongly promoted among men, although the younger generation has widely adopted a nonsmoking lifestyle. For women, efforts for preventing the onset of smoking, while necessary among the younger generation, should even be enhanced among middle-aged women.

Background: Trends in lung cancer mortality among young adults, which are important for projecting future trends, have not been explored previously in Japan. Methods: Using data from the National Vital Statistics between 1958 and 2003, we compiled lung cancer mortality by sex and 5-year birth cohort among young adults aged 20–49. Results: Mortality among those aged 20–29 has consistently decreased regardless of sex. There were birth cohort effects in mortality from lung cancer, although these were less evident among women than among men. Both men and women born in the 1930s had lower mortality rates, while those born after 1940 had higher lung cancer mortality rates. Mortality rates appear to be declining for male birth cohorts born after 1950 and female birth cohorts after 1960, although these trends may not be stable due to the small number of deaths in these cohorts. Conclusion: Lung cancer mortality trends appear to be decreasing among young adults. This might be associated with the lower mortality of birth cohorts after 1950 for men and the 1960s birth cohorts for women. Careful monitoring is needed to confirm continuation of these declining trends.

Oscillation criteria for fourth-order quasilinear ordinary differential equations are obtained. An application to binary semilinear elliptic systems is also given.

OBJECTIVE In Japan, population-based cancer incidence data are reported several years behind the latest year of cancer mortality data. To bridge this gap, we aimed to determine a short-term projection method for cancer incidence. METHODS Data between 1985 and 2007 were obtained from the population-based cancer registries in four prefectures (Miyagi, Yamagata, Fukui and Nagasaki). Three projection models were examined: generalized linear model with age and period (A + P linear); generalized linear model with age, period and their interactions (A*P linear); and generalized additive model with age, period and their interactions smoothed by spline (A*P spline). We performed a 5-year projection for the years 2000 and 2005, based on the data of 1985-95 and 1985-2000, respectively. Seven cancer sites (stomach, liver, colorectal, lung, female breast, cervix uteri and prostate) and all cancers combined were analyzed. The accuracy of projection was evaluated by whether each observed number fell within the 95% confidence interval of the projected number. RESULTS The A*P spline model accurately projected 8 of 13 cancer site-sex combinations, whereas the number of site-sex combinations of accurate projection was 2 and 6 for A + P linear and A*P linear models, respectively. For liver and colorectal cancers, the A*P spline model alone performed accurate projections; the relative differences between projected and observed numbers of cancer incidence ranged between -0.4 and +10.9% for the A*P spline, and between +7.4 and +37.6% for the other two models. All three models failed to project sudden increases in prostate cancer between 2000 and 2005. CONCLUSIONS The A*P spline model is a candidate method for the projection of cancer incidence in Japan. However, we need a continuous validation for prostate cancer.

Microtia is thought to have a multifactorial inheritance, but several investigators disagree. Here we report our survey of the hereditary factors and possible causes. We conducted a questionnaire survey of 428 patients with microtia who were being treated at two hospitals from September 2006 to September 2008. We recorded their age, sex, affected side, duration of gestation, birth weight, age of parents at patients' birth, accompanying malformations, number of siblings, familial occurrence, smoking habit of parents, and medication/disorders of mother during pregnancy, and analysed the results. There were preponderances of male (61%), unilateral (90%) and right-sided disease (59%). Other than the first and second branchial arch syndrome, microtia is often accompanied by other congenital deformities, in particular congenital heart disease; cleft lip, or palate, or both; vertebral defects; and anomalies of extremities. The occurrence in first-degree relatives was 2%. Most maternal disorders and medication taken during pregnancy were common and there was no clear link. Statistically, there was a tendency to low birth weight and high maternal age, but it is not possible to identify these as a specific cause of microtia. Multifactorial inheritance is unlikely to be the cause of microtia as there was only one finding in agreement with its widely accepted characteristics. However, we cannot completely discount it as there were too few cases in some groups to make a judgement.

The Japan Cancer Surveillance Research Group estimated the cancer incidence in 2006 as part of the Monitoring of Cancer Incidence in Japan (MCIJ) project, on the basis of data collected from 15 of 32 population-based cancer registries. The total number of incidences in Japan for 2006 was estimated as 664 398 (C00-C96). The leading cancer site was stomach for men and breast for women. Age-standardized incidence rates remained at almost the same level as for the previous 3 years.

The aim of this study was to develop a dose calculation method which is applicable to the interseed attenuation and the geometry lacking the equilibrium radiation scatter conditions in brachytherapy.The dose obtained from measurement with a radiophotoluminescent glass rod dosimeter (GRD) was compared to the dose calculated with the Monte Carlo (MC) code "EGS5," using the 125I source structure detailed in by Kennedy et al. The GRDs were irradiated with 125I Oncoseed 6711 in a human head phantom. The phantom was a cylinder made of 2 mm thick PMMA with a diameter of 18 cm and length of 16 cm. Some of the GRD positions were so close to the phantom surface that the backscatter margin was less than 5 cm, insufficient for photons.The EGS5 simulations were found to reproduce the relative dose distributions as measured with the GRDs to within 25% uncertainty in the geometry lacking the equilibrium radiation scatter conditions. The absolute value of the GRD measurement agreed with the American Association of Physicist in Medicine Task Group No 43 Updated Protocol (AAPM-TG43U1) formalism to within 3% of the reference point (r = 1 cm, theta = 90 degrees), where the TG43U1 is especially reliable because of the abundant data accumulation in composing the formalism. The factor to normalize the measured or calculated dose to the TG43U1 estimate at the reference point was evaluated to be 0.97 for the GRD measurement and 1.8 for the MC calculation, which uses the integration of the apparent activity with the time as the amount of disintegration during the irradiation. Also, F(r,theta) and g(r) estimated by this calculation method were consistent with those proposed in the TG43U1.The results of this investigation support the validity of both the MC calculation method and GRD measurement in this study as well as the TG-43U1 formalism. Also, this calculation is applicable to interseed attenuation and the geometry lacking the equilibrium radiation scatter.

Cancer has been the primary cause of death in Japan for many years and accurate cancer incidence data are necessary in order to make plans for cancer control. Although population-based cancer registries are the best answer, regrettably there are still many regions with low accuracy registries. In an alternative estimation, cancer incidences have been analyzed by age-period-cohort (APC) models, allowing future prediction of cancer incidences in 2004. Considering the unexpectedly rapid aging of the Japanese population after this figure was reported, it would be worthwhile to examine more recent data. In this study, we therefore projected major cancer incidences based on the earlier results leaving estimated values for the age and cohort effects. Relating to the period effect, the most adequate scenario was selected from 12 projection methods. Furthermore, incidences when registration rates varied between 70 and 100% were calculated. As a result, different trends from reported incidences were observed for liver cancer in males, and trends of registration rates differed by sites. Until stable accurate registration data become available, it is difficult to judge whether predicted increase is real or only looks so because the registration rate is not 100%. However, it is clearly necessary to continuously observe variation in cancer incidences.

The Japan Cancer Surveillance Research Group is involved in cancer monitoring in Japan (1–3). This group estimated the cancer incidence in 2003 as part of the Monitoring of Cancer Incidence in Japan (MCIJ) project, on the basis of data collected from 13 of 31 population-based cancer registries: Miyagi, Yamagata, Chiba, Kanagawa, Niigata, Fukui, Shiga, Osaka, Tottori, Okayama, Hiroshima, Saga and Nagasaki. If data from all 31 registries were used, this would have led to a large underestimation of national cancer incidence because of under-registration. The methods of registry selection, estimation of incidence and the limitations of these methods have been explained in previous studies (4–6). There were two major methodologic changes in the present study: (i) this was the first time we invited all 31 population-based cancer registries in Japan to participate, and from these we selected the 13 cancer registries with high-quality data in order to estimate the national incidence, and (ii) in consideration of timeliness, we did not apply the moving average which calculates the annual mean incidence rates of a year by using preceding and following years, and we used 2003 data alone for the national estimation. Because of the enlargement of the coverage area, Hiroshima prefecture was newly selected as one of the registries with high-quality data for the national estimation, but the other registries remained since the previous estimations. In 2007, we estimated incidences with and without the moving average based on the same registry data to compare the two methods. In conclusion, the estimated incidence without the moving average was comparatively unstable from year to year, but the gaps of the incidence numbers between the two estimations were subtle. These new methods therefore do not bring about changes in the estimated incidence numbers. The number of incidences, crude rates, age-standardized rates and completeness of registration in 2003 are shown in Table 1, and the age-specific number of incidences and the rates according to sex and primary site are shown in Tables 2 and 3. The total number of incidences in Japan for 2003 was estimated as 620 011 (C00–C96). The time trends of age-standardized incidence rates for the five major sites and maleand female-specific sites in 1975–2003 are shown in Fig. 1 (standard population: the world population) and in Fig. 2 (standard population: the 1985 Japanese model population). The leading cancer site according to the crude and age-standardized incidence rates was the stomach for men and breast for women, as shown in Figs 1 and 2. The apparent increase in age-standardized incidence rates in 2003 is considered to be caused primarily by the development of hospital-based cancer registry in designated cancer care hospitals. The estimated cancer incidence data in Japan by sex, site, 5-year age group and calendar year during the period 1975–2003 are available as a booklet (7) and as an electronic database on the website (http://ganjoho.ncc.go.jp/ professional/statistics/statistics.html).

The number of cancer incidences, crude incidence rates, age-standardized incidence rates in 2002 in Japan are estimated. The estimated total number of incidences was 570,598.

The concepts of lifetime and age-conditional probabilities of developing and dying of cancer are introduced as indexes to understand the risk of cancer. In this paper, we estimated the lifetime and age-conditional probabilities of developing and dying of cancer in 2001 and 2005, respectively, in Japan. It is estimated that one in two Japanese males and one in three females will develop cancer, and one in four Japanese males and one in six females will die of cancer. Moreover, the probabilities of developing cancer within specific decades of age are obtained as the short-term risks.

The purpose of this paper is to investigate the effect of vaccination on periodic structures of measles epidemics in Japan. We carried out spectral analysis for time series data of measles notifications collected in Japan. It was confirmed that the interepidemic period, which corresponds to the interval between major epidemics of measles, increases as the vaccination ratio increases. This result was supported by a theory based on a mathematical model for epidemics of infectious diseases. It was suggested that the interepidemic period is useful to estimate the effect of vaccination on measles incidences quantitatively.

The Japan Cancer Surveillance Research Group and the Research Group for Population-based Cancer Registration in Japan have estimated cancer incidences in Japan from 1975 to 2000 based on selected population-based cancer registries (1). However, these estimations were restricted to major cancer sites. Neither more detailed sites nor histological type have yet been reported, although these analyses are of clinical interest. Our research group collected data on newly diagnosed cancers between 1993 and 2001 from 15 population-based cancer registries in Japan (Miyagi, Yamagata, Chiba (model area), Kanagawa, Niigata, Fukui, Aichi, Shiga, Osaka, Tottori, Okayama, Saga, Nagasaki, Kumamoto and Okinawa) (1). Detailed analysis of cancer, including rare sites, became possible based on approximately 1.37 million cases of cancer incidence over 9 years. This article briefly reports on childhood cancers and histological types of bone, penis and testis cancer. For each site, we calculated the proportion of cases with death certificate only (DCO), then excluded registries with high proportions of DCO (Tottori and Kumamoto were excluded from the analysis of childhood cancer and bone cancer). Data from Okayama prefecture with diagnosis years of 1993-1995 were excluded because registered cases in this period were restricted to stomach, lung, colon, rectum, breast and uterus cancer.

Background: Accurate cancer incidence data are needed to plan, monitor and evaluate national cancer control programs. In Japan, however, such information is not available owing to incomplete cancer registries. In order to attain incidence estimation adjusted to account for this incomplete information, we have developed a new method. Methods: We developed a nonlinear regression model between observed incidence/mortality ratios and proportions of death certificate notification to observed incidence in various cancer registries. This model enables us to obtain the 'true incidence/mortality ratio', which, in the regression curve, is at zero point for the proportion of death certificate notifications. This is an ideal registration state without any missing cases. By multiplying it by the number of cancer mortalities from the National Vital Statistics, corrected cancer incidence can be estimated. Results: Applying this method for the estimation of the Japanese cancer incidence in 1997, we obtained the 'true incidence/mortality ratios' of 2.074 for men and 2.587 for women. Cancer incidences in Japan for 1997 were thus estimated to be 346 000 for men and 280 000 for women. Conclusions: A new method is proposed to estimate the national cancer incidence after adjusting for completeness of cancer registries. This method enables us to more accurately estimate the cancer incidence in a country where several cancer registries exist with various degrees of completeness of registration.