[Defining sensitivity and specificity for quality control of organized cancer screening using Prefectural Cancer Registry data in Japan].

Objective　To decrease cancer mortality by implementing cancer screening programs, rigorous quality control measures that utilize standardized indicators are imperative. In Japan, although each municipality performing cancer screening programs implements quality control for their programs using the checklist authorized by the Ministry of Health, Labour and Welfare, compliance with all the items listed is not possible because calculating sensitivity and specificity using cancer registry data is difficult under these circumstances. This report elucidates the methodology for calculating indicators, including sensitivity and specificity, by delineating the parameters of false-negative cases within population-based cancer screening programs in Japan. Furthermore, the inherent challenges associated with ensuring the quality control of cancer screening procedures are expounded upon in this report.Method　Data from the Prefectural Cancer Registry of Japan and cancer screening records compiled by municipalities were used to differentiate true-positive, true-negative, false-positive, and false-negative cases based on the combination of screening test outcomes and subsequent cancer incidence.Results　A false-negative case was defined as an examinee who received a cancer diagnosis within one year after undergoing the screening test, notwithstanding the negative judgment of the cancer screening decision. The duration for judgment of true-positive, true-negative, and false-negative cases was also extended to one year. Cancer identification after cancer screening was ascertained using data from the Prefectural Cancer Registry, ensuring uniform categorization of the four cases. Subsequently, sensitivity and specificity values were calculated for municipalities conducting cancer screening programs.Conclusion　Sensitivity and specificity are indispensable metrics for the inherent quality control of cancer screening because these parameters directly assess the efficacy of screening tests. The anticipated increase in the number of municipalities engaged in comprehensive quality control of cancer screening in Japan is poised to enhance the efficiency of cancer control policies. This augmentation will be accomplished through the meticulous utilization of the sensitivity and specificity values elucidated in the present report. The forthcoming challenges involve the proliferation of medical institutes reporting their adherence to the checklist stipulated by the National Cancer Center of Japan and the widespread dissemination of fundamental knowledge pertaining to cancer screening.

Effectiveness of hinge craniotomy as an alternative to decompressive craniectomy for acute subdural hematoma.

BACKGROUND: Acute subdural hematoma (ASDH) is a life-threatening condition, and hematoma removal is necessary as a lifesaving procedure when the intracranial pressure is highly elevated. However, whether decompressive craniectomy (DC) or conventional craniotomy (CC) is adequate remains unclear. Hinge craniotomy (HC) is a technique that provides expansion potential for decompression while retaining the bone flap. At our institution, HC is the first-line operation instead of DC for traumatic ASDH, and we present the surgical outcomes. METHODS: From January 1, 2017, to December 31, 2022, 372 patients with traumatic ASDH were admitted to our institution, among whom 48 underwent hematoma evacuation during the acute phase. HC was performed in cases where brain swelling was observed intraoperatively. If brain swelling was not observed, CC was selected. DC was performed only when the brain was too swollen to allow replacement of the bone flap. We conducted a retrospective analysis of patient demographics, prognosis, and subsequent cranial procedures for each technique. RESULTS: Of the 48 patients, 2 underwent DC, 23 underwent HC, and 23 underwent CC. The overall mortality rate was 20.8% (10/48) at discharge and 30.0% (12/40) at 6 months. The in-hospital mortality rates for DC, HC, and CC were 100% (2/2), 21.7% (5/23), and 13.0% (3/23), respectively. Primary brain injury was the cause of death in five patients whose brainstem function was lost immediately after surgery. No fatalities were attributed to the progression of postoperative brain herniation. In only one case, the cerebral contusion worsened after the initial surgery, leading to brain herniation and necessitating secondary DC. CONCLUSIONS: The strategy of performing HC as the first-line operation for ASDH did not increase the mortality rate compared with past surgical reports and required secondary DC in only one case.

Mapping recommendations towards an Asian Code Against Cancer (ACAC) as part of the World Code Against Cancer Framework: an Asian National Cancer Centers Alliance (ANCCA) initiative.

This paper outlines the process undertaken by Asian National Cancer Centers Alliance (ANCCA) members in working towards an Asian Code Against Cancer (ACAC). The process involves: (i) identification of the criteria for selecting the existing set of national recommendations for ACAC (ii) compilation of existing national codes or recommendations on cancer prevention (iii) reviewing the scientific evidence on cancer risk factors in Asia and (iv) establishment of one or more ACAC under the World Code Against Cancer Framework. A matrix of national codes or key recommendations against cancer in ANCCA member countries is presented. These include taking actions to prevent or control tobacco consumption, obesity, unhealthy diet, physical inactivity, alcohol consumption, exposure to occupational and environmental toxins; and to promote breastfeeding, vaccination against infectious agents and cancer screening. ANCCA will continue to serve as a supportive platform for collaboration, development, and advocacy of an ACAC jointly with the International Agency for Research on Cancer/World Health Organization (IARC/WHO).

Disparities and determinants of testing for early detection of cervical cancer among Nepalese women: evidence from a population-based survey.

BACKGROUND: Cervical cancer (CC) presents a considerable challenge in South Asia, notably in Nepal, where screening remains limited. Past research in Nepal lacked national representation and a thorough exploration of factors influencing CC screening, such as educational and socioeconomic disparities. This study aims to measure these gaps and identify associated factors in testing for early detection of CC among Nepalese women. METHODS: Data from the 2019 Nepal Noncommunicable Disease Risk Factors survey (WHO-STEPwise approach to noncommunicable risk factor surveillance), involving 2,332 women aged 30-69 years, were used. Respondents were asked if they had undergone CC testing through VIA, Pap smear, or HPV test ever or in the past five years. The slope index of inequality (SII) and relative concentration index (RCI) were used to measure socioeconomic and education-based disparities in CC test uptake. RESULTS: Only 7.1% (95% CI: 5.1-9.9) Nepalese women had ever undergone CC testing, while 5.1% (95% CI: 3.4-7.5) tested within the last five years. The ever uptake of CC testing was 5.1 percentage points higher (SII: 5.1, 95% CI: -0.1 to 10.2) among women from richest compared to poorest households. Education-based disparities were particularly pronounced, with a 13.9 percentage point difference between highly educated urban residents and their uneducated counterparts (SII: 13.9, 95% CI: 5.8 to 21.9). CONCLUSIONS: Less than one in ten women in Nepal had a CC testing, primarily favoring higher educated and wealthier individuals. IMPACT: Targeted early detection and CC screening interventions are necessary to address these disparities and improve access and uptake.

Trends in patterns of treatment and survival of colorectal cancer patients using cancer registry data in Japan: 1995-2015.

Recent advances in treating colorectal cancer (CRC) have increased the importance of multidisciplinary treatment. This study aimed to clarify trends in the treatment and survival of CRC using population-based cancer registry data in Japan. We analyzed the survival of CRC cases diagnosed from 1995 through 2015 from a population-based cancer registry of six prefectures. The year of diagnosis was classified into five periods, and the trends in the detailed categorization of treatments and survival were identified. We calculated net survival and excess hazard of death from cancer using data on 256,590 CRC patients. The use of laparoscopic surgery has been increasing since 2005 and accounts for the largest proportion of treatment types in the most recent period. Net survival of CRC patients diagnosed after 2005 remained high for laparoscopic surgery and endoscopic surgery (endoscopic mucosal resection or endoscopic submucosal dissection). There was an upward trend in treatment with chemotherapy in addition to open and laparoscopic surgery. Using the excess hazard ratio at the regional stage since 2005, there has been a significant improvement in survival in the younger age group and the rectum cancer group. By type of treatment, there was a tendency toward significant improvement in the open surgery + chemotherapy group. We clarified the trends in treating CRC and the associated trends in survival. Continuous survey based on population-based data helps monitor the impact of developments in treatment.

Time trend analysis of rare cancer incidence 2011-2018: Nationwide population-based cancer registries in Japan.

Rare cancers collectively account for a significant proportion of the overall cancer burden in Japan. We aimed to describe and examine the incidence of each rare cancer and the temporal changes using the internationally agreed rare cancer classification. Cancer cases registered in regional population-based cancer registries from 2011 to 2015 and the National Cancer Registry (NCR) from 2016 to 2018 were classified into 18 families, 68 Tier-1 cancer groupings, and 216 single cancer entities based on the RARECAREnet list. Crude incidence rates and age-standardized incidence rates (ASR) were calculated for Tier-1 and Tier-2 cancers. The annual percent change and the 95% and 99% confidence limits for annual ASR for each of the 68 Tier-1 cancers were estimated using the log-linear regression of the weighted least squares method. The differences in ASRs between 2011 and 2018 were evaluated as an absolute change. A total of 5,640,879 cases were classified into Tier-1 and Tier-2 cancers. The ASRs of 18 out of 52 Tier-1 cancers in the rare cancer families increased, whereas the ASR for epithelial tumors of gallbladder decreased. The ASRs of 6 out of the 16 Tier-1 cancers in the common cancer families increased, whereas those of epithelial tumors of stomach and liver decreased. There was no significant change in the incidence of the other 40 Tier-1 cancers. The incidence of several cancers increased due to the dissemination of diagnostic concepts, improved diagnostic techniques, changes in coding practice, and the initiation of the NCR.

Do the general public get cancer statistics?-a questionnaire survey in Japan.

OBJECTIVES: The public does not always understand key information conveyed by epidemiologists and statisticians. The purpose of this study was to understand the level of public access to, trust in, and comprehension of, cancer statistics through a population-based survey in Japan. METHODS: We used an online research method, requesting online responses to a 15-question questionnaire. The survey was sent to males and females aged 20 years and older, selected by sex, age and prefecture to match the national population proportions shown in the latest census. The final number of valid responses was 10 477. The statistical analyses mainly used χ2 testing. RESULTS: Respondents were not frequently exposed to cancer statistics regardless of sex or age group, nor did they necessarily have confidence in the statistics. The increase of collected information and trust in cancer statistics was aligned with increasing age and cancer exposure. Respondents found Relative Risk and Relative Survival Rate easier to understand and more useful than the Standardized Incidence Ratio. In addition, those with cancer experience, higher income and were elderly gave more accurate responses when asked questions related to cancer incidence and probability of getting cancer. CONCLUSIONS: Our respondents showed limited familiarity with cancer statistical indicators. Enhanced awareness of indicators such as infographics and visual tools has the potential to enhance cancer visibility, thereby promoting public prevention and early detection efforts. Educating cancer patients about pertinent indicators can boost their confidence in managing their condition. Conversely, the introduction of indicators unrelated to the public should be discouraged.

Subsite-specific trends in mid- and long-term survival for head and neck cancer patients in Japan: A population-based study.

Advances in diagnostic techniques and treatment modalities have impacted head and neck cancer (HNC) prognosis, but their effects on subsite-specific prognosis remain unclear. This study aimed to assess subsite-specific trends in mid- and long-term survival for HNC patients diagnosed from 1993 to 2011 using data from population-based cancer registries in Japan. We estimated the net survival (NS) for HNC by subsite using data from 13 prefectural population-based cancer registries in Japan. Changes in survival over time were assessed by multivariate excess hazard model of mortality. In total, 68,312 HNC patients were included in this analysis. We observed an overall improvement in 5-year NS for HNC patients in Japan. However, survival varied among subsites of HNC, with some, such as naso-, oro- and hypopharyngeal cancers, showing significant improvement in both 5- and 10-year NS, whereas others such as laryngeal cancer showed only a slight improvement in 5-year NS and no significant change in 10-year NS after adjustment for age, sex and stage. In conclusion, the study provides insights into changing HNC survival by site at the population level in Japan. Although advances in diagnostic techniques and treatment modalities have improved survival, these improvements are not shared equally among subsites.

Feasibility of monitoring Global Breast Cancer Initiative Framework key performance indicators in 21 Asian National Cancer Centers Alliance member countries.

Background: The Global Breast Cancer Initiative (GBCI) Framework, launched by the World Health Organisation (WHO) in 2023, emphasises assessing, strengthening, and scaling up services for the early detection and management of breast cancer. This study aims to determine the feasibility of monitoring the status of breast cancer control in the 21 Asian National Cancer Centers Alliance (ANCCA) countries based on the three GBCI Framework key performance indicators (KPIs): stage at diagnosis, time to diagnosis, and treatment completion. Methods: We reviewed published literature on breast cancer control among 21 ANCCA countries from May to July 2023 to establish data availability and compiled the latest descriptive statistics and sources of the indicators using a standardised data collection form. We performed bivariate Pearson's correlation analysis to measure the strength of correlation between stage at diagnosis, mortality and survival rates, and universal health coverage. Findings: Only 12 (57%) ANCCA member countries published national cancer registry reports on breast cancer age-standardised incidence rate (ASIR) and age-standardised mortality rate (ASMR). Indonesia, Myanmar, and Nepal had provincial data and others relied on WHO's Global Cancer Observatory (GLOBOCAN) estimates. GLOBOCAN data differed from the reported national statistics by 5-10% in Bhutan, Indonesia, Iran, the Republic of Korea, Singapore, and Thailand and >10% in China, India, Malaysia, Mongolia, and Sri Lanka. The proportion of patients diagnosed in stages I and II strongly correlated with the five-year survival rate and with the universal health coverage (UHC) index. Three countries (14%) reported national data with >60% of invasive breast cancer patients diagnosed at stages I and II, and a five-year survival rate of >80%. Over 60% of the ANCCA countries had no published national data on breast cancer staging, the time interval from presentation to diagnosis, and diagnosis to treatment. Five (24%) countries reported data on treatment completion. The definition of delayed diagnosis and treatment completion varied across countries. Interpretation: GBCI's Pillar 1 KPI correlates strongly with five-year survival rate and with the UHC index. Most ANCCA countries lacked national data on cancer staging, timely diagnosis, and treatment completion KPIs. While institutional-level data were available in some countries, they may not represent the nationwide status. Strengthening cancer surveillance is crucial for effective breast cancer control. The GBCI Framework indicators warrant more detailed definitions for standardised data collection. Surrogate indicators which are measurable and manageable in country-specific settings, could be considered for monitoring GBCI indicators. Ensuring UHC and addressing health inequalities are essential to early diagnosis and treatment of breast cancer. Funding: Funding for this research article's processing fee (APC) will be provided by the affiliated institution to support the open-access publication of this work. The funding body is not involved in the study design; collection, management, analysis and interpretation of data; or the decision to submit for publication. The funding body will be informed of any planned publications, and documentation provided.

Head and neck cancers survival in Europe, Taiwan, and Japan: results from RARECAREnet Asia based on a privacy-preserving federated infrastructure.

Background: The head and neck cancers (HNCs) incidence differs between Europe and East Asia. Our objective was to determine whether survival of HNC also differs between European and Asian countries. Methods: We used population-based cancer registry data to calculate 5-year relative survival (RS) for the oral cavity, hypopharynx, larynx, nasal cavity, and major salivary gland in Europe, Taiwan, and Japan. We modeled RS with a generalized linear model adjusting for time since diagnosis, sex, age, subsite, and histological grouping. Analyses were performed using federated learning, which enables analyses without sharing sensitive data. Findings: Five-year RS for HNC varied between geographical areas. For each HNC site, Europe had a lower RS than both Japan and Taiwan. HNC subsites and histologies distribution and survival differed between the three areas. Differences between Europe and both Asian countries persisted even after adjustments for all HNC sites but nasal cavity and paranasal sinuses, when comparing Europe and Taiwan. Interpretation: Survival differences can be attributed to different factors including different period of diagnosis, more advanced stage at diagnosis, or different availability/access of treatment. Cancer registries did not have stage and treatment information to further explore the reasons of the observed survival differences. Our analyses have confirmed federated learning as a feasible approach for data analyses that addresses the challenges of data sharing and urge for further collaborative studies including relevant prognostic factors.

Economic burden of cancer attributable to modifiable risk factors in Japan.

Controlling avoidable causes of cancer may save cancer-related healthcare costs and indirect costs of premature deaths and productivity loss. This study aimed to estimate the economic burden of cancer attributable to major lifestyle and environmental risk factors in Japan in 2015. We evaluated the economic cost of cancer attributable to modifiable risk factors from a societal perspective. We obtained the direct medical costs for 2015 from the National Database of Health Insurance Claims and Specific Health Checkups of Japan, and estimated the indirect costs of premature mortality and of morbidity due to cancer using the relevant national surveys in Japan. Finally, we estimated the economic cost of cancer associated with lifestyle and environmental risk factors. The estimated cost of cancer attributable to lifestyle and environmental factors was 1,024,006 million Japanese yen (¥) (8,460 million US dollars [$]) for both sexes, and ¥673,780 million ($5,566 million) in men and ¥350,226 million ($2,893 million) in women, using the average exchange rate in 2015 ($1 = ¥121.044). A total of ¥285,150 million ($2,356 million) was lost due to premature death in Japan in 2015. Indirect morbidity costs that could have been prevented were estimated to be ¥200,602 million ($1,657 million). Productivity loss was highest for stomach cancer in men (¥28,735 million/$237 million) and cervical cancer in women (¥24,448 million/$202 million). Preventing and controlling cancers caused by infections including Helicobacter pylori, human papillomavirus and tobacco smoking will not only be life-saving but may also be cost-saving in the long run.

Cancer Prevalence Projections in Japan and Decomposition Analysis of Changes in Cancer Burden, 2020-2050: A Statistical Modeling Study.

BACKGROUND: We provide comprehensive sex-stratified projections of cancer prevalence for 22 cancer sites in Japan from 2020 to 2050. METHODS: Using a scenario-based approach, we projected cancer prevalence by combining projected incidence cases and survival probabilities. Age-specific incidences were forecasted using age-period-cohort models, while survival rates were estimated using a period-analysis approach and multiple parametric survival models. To understand changes in cancer prevalence, decomposition analysis was conducted, assessing the contributions of incidence, survival, and population demographics. RESULTS: By 2050, cancer prevalence in Japan is projected to reach 3,665,900 (3,210,200 to 4,201,400) thousand cases, representing a 13.1% increase from 2020. This rise is primarily due to a significant increase in female survivors (+27.6%) compared with a modest increase in males (+0.8%), resulting in females overtaking males in prevalence counts from 2040 onward. In 2050, the projected most prevalent cancer sites in Japan include colorectal, female breast, prostate, lung, and stomach cancers, accounting for 66.4% of all survivors. Among males, the highest absolute increases in prevalence are projected for prostate, lung, and malignant lymphoma cancers, while among females, the highest absolute increases are expected for female breast, colorectal, and corpus uteri cancers. CONCLUSIONS: These findings emphasize the evolving cancer prevalence, influenced by aging populations, changes in cancer incidence rates, and improved survival. Effective prevention, detection, and treatment strategies are crucial to address the growing cancer burden. IMPACT: This study contributes to comprehensive cancer control strategies and ensures sufficient support for cancer survivors in Japan.

Stent retrieval for free-floating thrombus attached to carotid artery stenosis: A report of two cases.

Background: We report two cases who underwent mechanical thrombectomy using a stent retriever in advance of urgent carotid artery stenting (CAS) for carotid artery stenosis with free-floating thrombus (FFT). Case Description: Two patients showing symptomatic carotid artery stenosis with FFT underwent urgent endovascular surgery due to progressive neurological symptoms. The first case showed an FFT with 70% internal carotid artery (ICA) stenosis. After the completion of the common and external carotid artery balloon and distal ICA filter protection, we deployed a 6-mm-diameter stent retriever in the distal part of the stenosis. The white thrombus was retrieved; the angiographic shadow of the FFT disappeared; and CAS was performed. In the second case, due to a 90% severe stenosis lesion with FFT, balloon angioplasty was performed on the lesion using the push wire of the stent retriever. After angioplasty, the stent retriever was smoothly retrieved, and CAS was performed. Postoperative magnetic resonance imaging showed an increase in cerebral embolism in the first case; however, the patient's neurological symptoms improved. The second case showed in-stent plaque protrusion and required two additional stent placements; the patient showed no worsening of his neurological symptoms. Conclusion: In cases of carotid artery stenosis with FFT, it is technically possible to retrieve a thrombus with a stent retriever. Although thrombus removal may help reduce the risk of ischemic complications in a series of urgent CAS procedures, there are concerns such as mechanical irritation to the carotid artery plaque, and its indications and alternative treatments should be carefully considered.

Trends in non-Hodgkin lymphoma mortality rate in Japan and the United States: A population-based study.

Characterizing trends in mortality rates with consideration of trends in incidence rates at the population level could help identify unmet needs in public health and provide essential indicators of cancer control. In the late 20th century, the arrival of the first molecular targeted agent, rituximab, for non-Hodgkin lymphoma (NHL) led to a paradigm shift in NHL treatment. However, the public health impact of this arrival has not been fully clarified. Here, we evaluated trends in the mortality and incidence rates of NHL in Japan and the United States. Age-standardized rates of mortality reversed after the introduction of rituximab, around 2000, beginning to decline significantly with annual percent changes (95% confidence interval) of -2.6% (-3.6% to -1.6%) in Japan and - 3.9% (-4.2% to -3.5%) in the United States. Despite an increase in incidence, the mortality in all age groups weakened the upward trends or decreased in both countries. From a long-term perspective, the trends in mortality rates differed between the countries. In the United States, the mortality rate has declined continuously since the introduction of rituximab, with a declining incidence rate. In contrast, in Japan, the mortality rate stopped declining and the incidence rate increased remarkably. The introduction of rituximab has had a substantial impact at the population level across a wide range of individuals. To reduce the disease burden in terms of mortality, elucidating risk factors that lead to a decreasing incidence rate is warranted for NHL, as well as further development of novel treatments.

Changing trends in the risk factors for second primary malignancies after autologous stem cell transplantation for multiple myeloma before and after the introduction of proteasome inhibitors and immunomodulatory drugs.

The incidence of second primary malignancies (SPM) in long-term survivors of multiple myeloma (MM) is increasing because of increased life expectancy. We retrospectively analyzed the risk factors for SPM in patients with MM after autologous stem cell transplantation (ASCT) before and after the introduction of proteasome inhibitors and immunomodulatory drugs (IMiDs). In total, 2,340 patients newly diagnosed with MM who underwent ASCT between 1995 and 2016 were enrolled in this study. Forty-three patients developed SPM (29 solid, 12 hematological, and 2 unknown tumors), with cumulative incidence rates of 0.8% and 2.5% at 24 and 60 months, respectively. The cumulative incidence rates of hematological and solid SPM at 60 months were 0.8% and 1.8%, respectively. The overall survival (OS) rate at 60 months after ASCT was 62.9% and the OS rates after the diagnosis of SPM at 24 months were 72.2% for hematological SPM and 70.9% for solid SPM. Multivariate analysis revealed that the use of IMiDs (P=0.024) and radiation (P=0.002) were significant independent risk factors for SPM. The probabilities of developing SPM and death due to other causes (mainly MM) at 60 months were 2.5% and 36.5%, respectively, indicating that the risk of SPM was lower than that of death from MM. Furthermore, SPM between the pre-novel and novel agent eras (ASCT between 2007 and 2016) groups significantly increased (1.9% vs. 4.3% at 60 months; P=0.022). The early occurrence of SPM after ASCT should be monitored cautiously.

A population-based comparison of patients with metastatic esophagogastric carcinoma between Japan and the Netherlands.

PURPOSE: Differences exist between Asian and Western patients with esophagogastric cancer, for example in terms of histological subtype and treatment strategies. This study aimed to compare characteristics and treatment between patients with metastatic esophagogastric cancer from Japan and the Netherlands using nationwide cancer registry data. METHODS: Patients diagnosed with metastatic esophageal or gastric cancer were included from the nationwide national cancer registry of Japan (2016-2019) and the Netherlands (2015-2020). Treatment strategies were analyzed using chi-squared tests. RESULTS: The proportion of patients with metastatic esophageal (16.0% vs 34.2%) and gastric cancer (14.9% vs 45.2%) were lower in Japan compared to the Netherlands. Japanese patients with metastatic esophageal adenocarcinoma (EAC), esophageal squamous cell carcinoma (ESCC) or gastric cancer (GC) were more often male and older compared to Dutch patients. Proportion of patients with metastatic disease who received surgical resection was higher in Japan compared to the Netherlands (EAC 9.3 vs 1.4%, p < 0.001; ESCC 10.7% vs 2.3%, p < 0.001; GC 12.0% vs 3.6% p < 0.001). Proportion of patients who received systemic therapy was also higher (EAC 44.8% vs 30.4%, p < 0.001; ESCC 26.6% vs 12.0%, p < 0.001; GC 50.7% vs 35.8% p < 0.001). CONCLUSIONS: Japanese patients less often presented with metastatic esophagogastric cancer and more often underwent surgical resection or received systemic therapy compared to Dutch patients. Further investigation should elucidate what the deliberations are in both Japan and the Netherlands and if more patients in the Netherlands could benefit from surgical resection or systemic therapy and whether this would translate in better survival and quality of life.

Cancer incidence and type of treatment hospital among children, adolescents, and young adults in Japan, 2016-2018.

Cancer in children, adolescents, and young adults (AYAs) although rare, is the leading disease-specific cause of death in Japan. This study aims to investigate cancer incidence and type of treatment hospital among children and AYAs in Japan. Cancer incidence data (2016-2018) for those aged 0-39 years were obtained from the Japanese population-based National Cancer Registry. Cancer types were classified according to the 2017 update of the International Classification of Childhood Cancer (Third Edition), and AYA Site Recode 2020 Revision. Cases were also categorized into three groups: those treated at core hospitals for pediatric cancer treatment (pediatric cancer hospitals [PCHs]), those treated at designated cancer care hospitals, and those treated at nondesignated hospitals. The age-standardized incidence rate was 166.6 (per million-person years) for children (age 0-14 years) and 579.0 for AYAs (age 15-39 years) (including all cancers and benign or uncertain-behavior central nervous system [CNS] tumors). The type of cancer varied with age: hematological malignancies, blastomas, and CNS tumors were common in children under 10 years, malignant bone tumors and soft tissue sarcomas were relatively common in teenagers, and in young adults over 20 years, carcinomas in thyroid, testis, gastrointestinal, female cervix, and breast were common. The proportion of cases treated at PCHs ranged from 20% to 30% for children, 10% or less for AYAs, and differed according to age group and cancer type. Based on this information, the optimal system of cancer care should be discussed.

Impact of cancer and other causes of death on mortality of cancer patients: A study based on Japanese population-based registry data.

Cancer registry data provide a very important source of information for improving our understanding of the epidemiology of various cancers. In this work, we estimated the 5-year crude probabilities of death from cancer and from other causes for five common cancers, namely stomach, lung, colon-rectum, prostate and breast, in Japan, using population-based registry data. Based on data on 344 676 patients diagnosed with one of these cancers between 2006 and 2008 in 21 prefectures participating in the Monitoring of Cancer Incidence in Japan (MCIJ) and followed-up for at least 5 years, we used a flexible excess hazard model to compute the crude probabilities of death for different combinations of sex, age and stage at diagnosis. For tumours diagnosed at the distant stage, as well as for regional lung tumours, the vast majority of deaths at 5 years in cancer patients were attributable to the disease itself (although this proportion was only around 60% in older prostate cancer patients). For localised and most regional tumours, the impact of other causes of death on the total mortality increased with age at diagnosis, especially for localised breast, colorectal and gastric cancer. By allowing the partition of the mortality experience of cancer patients into a cancer- and an other-cause-specific component, crude probability of death estimates provide insight into how the impact of cancer on mortality might differ among populations with different background mortality risks. This might be useful for informing discussions between clinicians and patients about treatment options.