Cost-effectiveness of preventive aspirin use and intensive downstaging polypectomy in patients with familial adenomatous polyposis: A microsimulation modeling study

OBJECTIVE

Although there is increasing evidence to suggest the cost-effectiveness of aspirin use to prevent colorectal cancer (CRC) in the general population, no study has assessed cost-effectiveness in patients with familial adenomatous polyposis (FAP), who are at high risk of developing CRC. We examined the cost-effectiveness of preventive use of low-dose aspirin in FAP patients who had undergone polypectomy in comparison with current treatment practice.

DESIGN

We developed a microsimulation model that simulates a hypothetical cohort of the Japanese population with FAP for 40 years. Three scenarios were created based on three intervention strategies for comparison with no intervention, namely intensive downstaging polypectomy (IDP) of colorectal polyps at least 5.0 mm in diameter, IDP combined with low-dose aspirin, and total proctocolectomy with ileal pouch-anal anastomosis (IPAA). Cost-effective strategies were identified using a willingness-to-pay threshold of USD 50,000 per QALY gained.

RESULTS

Compared with no intervention, all strategies resulted in extended QALYs (21.01-21.43 QALYs per individual) and showed considerably reduced colorectal cancer mortality (23.35-53.62 CRC deaths per 1000 individuals). Based on the willingness-to-pay threshold, IDP with low-dose aspirin was more cost-effective than the other strategies, with an incremental cost-effectiveness ratio of $57 compared with no preventive intervention. These findings were confirmed in both one-way sensitivity analyses and probabilistic sensitivity analyses.

CONCLUSION

This study suggests that the strategy of low-dose aspirin with IDP may be cost-effective compared with IDP-only or IPAA under the national fee schedule of Japan.

Simulation Models in Gastric Cancer Screening: A Systematic Review

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.

An in vitro verification of strength estimation for moving an 125I source during implantation in brachytherapy

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).

Long-term prognosis of human herpesvirus 6 reactivation following allogeneic hematopoietic stem cell transplantation

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.

Detecting a Local Cohort Effect for Cancer Mortality Data Using a Varying Coefficient Model

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.

A comparison of the dose distributions between the brachytherapy 125I source models, STM1251 and Oncoseed 6711, in a geometry lacking radiation equilibrium scatter conditions

The purpose of this study was to estimate the uncertainty in the dose distribution for the (125)I 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 (125)I 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.

Serological surveillance development for tropical infectious diseases using simultaneous microsphere-based multiplex assays and finite mixture models

Background

A strategy to combat infectious diseases, including neglected tropical diseases (NTDs), will depend on the development of reliable epidemiological surveillance methods. To establish a simple and practical seroprevalence detection system, we developed a microsphere-based multiplex immunoassay system and evaluated utility using samples obtained in Kenya.

Methods

We developed a microsphere-based immuno-assay system to simultaneously measure the individual levels of plasma antibody (IgG) against 8 antigens derived from 6 pathogens: Entamoeba histolytica (C-IgL), Leishmania donovani (KRP42), Toxoplasma gondii (SAG1), Wuchereria bancrofti (SXP1), HIV (gag, gp120 and gp41), and Vibrio cholerae (cholera toxin). The assay system was validated using appropriate control samples. The assay system was applied for 3411 blood samples collected from the general population randomly selected from two health and demographic surveillance system (HDSS) cohorts in the coastal and western regions of Kenya. The immunoassay values distribution for each antigen was mathematically defined by a finite mixture model, and cut-off values were optimized.

Findings

Sensitivities and specificities for each antigen ranged between 71 and 100%. Seroprevalences for each pathogen from the Kwale and Mbita HDSS sites (respectively) were as follows: HIV, 3.0% and 20.1%; L. donovani, 12.6% and 17.3%; E. histolytica, 12.8% and 16.6%; and T. gondii, 30.9% and 28.2%. Seroprevalences of W. bancrofti and V. cholerae showed relatively high figures, especially among children. The results might be affected by immunological cross reactions between W. bancrofti-SXP1 and other parasitic infections; and cholera toxin and the enterotoxigenic E. coli (ETEC), respectively.

Interpretation

A microsphere-based multi-serological assay system can provide an opportunity to comprehensively grasp epidemiological features for NTDs. By adding pathogens and antigens of interest, optimized made-to-order high-quality programs can be established to utilize limited resources to effectively control NTDs in Africa.

Monitoring the distribution of neglected tropical diseases (NTDs) is a key to controlling their spread in Africa. Currently, such surveillance is conducted independently for each NTD. To tackle this problem, we developed a microsphere-based system to permit simultaneous measurement of IgG antibody levels for antigens from six infectious diseases: Entamoeba histolytica, Leishmania donovani, Toxoplasma gondii, Wuchereria bancrofti, HIV, and Vibrio cholerae. Using this system, we conducted a serological survey using two health and demographic surveillance system (HDSS) areas in coastal and western Kenya. We randomly selected 4,600 individuals according to sex and age group, of whom 3411 agreed to participate in the study. Mathematical analyses of the distributions of the participants' reactivity to each antigen and the reactivity of the sero-positive and -negative controls indicated that this system could be used to monitor infections, especially, those associated with HIV, filariasis, toxoplasmosis, leishmaniasis, and amebiasis. For the practical development and eventual implementation of actual programs in Africa, pathogens and antigens of interest can be added to optimize made-to-order monitoring programs.

A dosimetry method for low dose rate brachytherapy by EGS5 combined with regression to reflect source strength shortage

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.

Measurement of the strength of iodine-125 seed moving at unknown speed during implantation in brachytherapy

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.

A dosimetry study of the Oncoseed 6711 using glass rod dosimeters and EGS5 Monte Carlo code in a geometry lacking radiation equilibrium scatter conditions

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.

MEM spectral analysis for predicting influenza epidemics in Japan

OBJECTIVES

The prediction of influenza epidemics has long been the focus of attention in epidemiology and mathematical biology. In this study, we tested whether time series analysis was useful for predicting the incidence of influenza in Japan.

METHODS

The method of time series analysis we used consists of spectral analysis based on the maximum entropy method (MEM) in the frequency domain and the nonlinear least squares method in the time domain. Using this time series analysis, we analyzed the incidence data of influenza in Japan from January 1948 to December 1998; these data are unique in that they covered the periods of pandemics in Japan in 1957, 1968, and 1977.

RESULTS

On the basis of the MEM spectral analysis, we identified the periodic modes explaining the underlying variations of the incidence data. The optimum least squares fitting (LSF) curve calculated with the periodic modes reproduced the underlying variation of the incidence data. An extension of the LSF curve could be used to predict the incidence of influenza quantitatively.

CONCLUSIONS

Our study suggested that MEM spectral analysis would allow us to model temporal variations of influenza epidemics with multiple periodic modes much more effectively than by using the method of conventional time series analysis, which has been used previously to investigate the behavior of temporal variations in influenza data.

Time series analysis of incidence data of influenza in Japan

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.

Cancer incidence and incidence rates in Japan in 2005: based on data from 12 population-based cancer registries in the Monitoring of Cancer Incidence in Japan (MCIJ) project

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.

Cancer incidence and incidence rates in Japan in 2004: based on data from 14 population-based cancer registries in the Monitoring of Cancer Incidence in Japan (MCIJ) Project

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.

Estimation of cancer incidence in Japan with an age-period-cohort model

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.

Cancer incidence and incidence rates in Japan in 2002: based on data from 11 population-based cancer registries

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.

Lifetime and age-conditional probabilities of developing or dying of cancer in Japan

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.

A Mathematical Estimation of True Cancer Incidence Using Data from Population-based Cancer Registries

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.

Trends in smoking by birth cohorts born between 1900 and 1977 in Japan

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.

Trends in Lung Cancer Mortality Among Young Adults in Japan

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.