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In Japan, cancer care hospitals designated by the national government have a surgical volume requirement of 400 annually, which is not necessarily defined based on patient outcomes. This study aimed to estimate surgical volume thresholds that ensure optimal 3-year survival for three periods. In total, 186 965 patients who had undergone surgery for solid cancers in 66 designated cancer care hospitals in Osaka between 2004 and 2012 were examined using data from a population-based cancer registry. These hospitals were categorized by the annual surgical volume of each 50 surgeries (eg, 0-49, 50-99, and so on). Using multivariable Cox proportional hazard regression, we estimated the adjusted 3-year survival probability per surgical volume category for 2004-2006, 2007-2009, and 2010-2012. Using the joinpoint regression model that computes inflection points in a linear relationship, we estimated the points at which the trend of the association between surgical volume and survival probability changes, defining them as surgical volume thresholds. The adjusted 3-year survival ranges were 71.7%-90.0%, 68.2%-90.0%, and 79.2%-90.3% in 2004-2006, 2007-2009, and 2010-2012, respectively. The surgical volume thresholds were identified at 100-149 in 2004-2006 and 2007-2009 and 200-249 in 2010-2012. The extents of change in the adjusted 3-year survival probability per increase of 50 surgical volumes were +4.00%, +6.88%, and +1.79% points until the threshold and +0.41%, +0.30%, and +0.11% points after the threshold in 2004-2006, 2007-2009, and 2010-2012, respectively. The existing surgical volume requirements met our estimated thresholds. Surgical volume thresholds based on the association with patient survival may be used as a reference to validate the surgical volume requirement.

The Japanese national and prefectural governments have accredited high‐capacity, high‐experience cancer care hospitals as “designated cancer care hospitals” to standardize cancer care, centralize patients, and improve clinical outcomes, but the performance of these designated hospitals has not been evaluated. We retrospectively compared 3‐year patient survival in national, prefectural, and nondesignated cancer care hospitals in 2010‐2012 in Osaka using registry‐based data of 86 456 surgically treated cancer patients aged 15 years or older. Hazard ratios and 3‐year survival probabilities were compared among national, prefectural, and nondesignated hospitals using a Cox proportional hazard regression model. Subgroup analyses for six cancers (stomach, colorectum, lung, breast, uterus, and prostate) and other cancers were carried out. In 2010‐2012, 36 634 (42.4%), 38 048 (44.0%), and 11 774 (13.6%) patients were treated at national, prefectural, and nondesignated hospitals, respectively. The mortality hazard for all‐site cancer was significantly lower in national and prefectural designated hospitals (adjusted hazard ratio 0.60 [95% confidence interval, 0.53‐0.68] and 0.72 [0.66‐0.80], respectively) than in nondesignated hospitals. The adjusted 3‐year survival probabilities for all‐site cancer were 86.6%, 84.2%, and 78.8% in national, prefectural, and nondesignated hospitals, respectively. Site‐specific subgroup analyses revealed significantly lower hazard ratios in national and prefectural hospitals than in nondesignated hospitals for stomach, colorectal, lung, breast, and other cancers. To conclude, the majority of cancer patients underwent surgeries at designated hospitals and had higher 3‐year survival probabilities than those treated at nondesignated hospitals. Further centralization of patients from nondesignated to designated hospitals could improve population‐level survival., This study assessed the centralization of cancer surgery in Osaka, by comparing the number and 3‐year survival from diagnosis of patients treated at designated cancer care hospitals with those treated at nondesignated cancer care hospitals. More than 85% of patients underwent surgeries at designated cancer care hospitals, and their 3‐year survival probability was significantly higher than those treated at nondesignated cancer care hospitals. Further centralization of patients, considering the incidence and prognosis per cancer type and the existing health‐care system capabilities, could improve population‐level survival.

This study focused on children as well as adolescents and young adults (AYAs) and aimed to examine trends in survival of leukemia over time using population‐based cancer registry data from Osaka, Japan. The study subjects comprised 2254 children (0‐14 years) and 2,905 AYAs (15‐39 years) who were diagnosed with leukemia during 1975‐2011. Leukemia was divided into four types: acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic myeloid leukemia (CML), and other leukemias. We analyzed 5‐year overall survival probability (5y‐OS), using the Kaplan‐Meier method and expressed time trends using the joinpoint regression model. For recently diagnosed (2006‐2011) patients, a Cox proportional hazards model was applied to determine predictors of 5y‐OS, using age group, gender, and treatment hospital as covariates. Over the 37‐year period, 5y‐OS greatly improved among both children and AYAs, for each leukemia type. Among AYAs, 5y‐OS of ALL improved, especially after 2000 (65% in 2006‐2011), when the pediatric regimen was introduced but was still lower than that among children (87% in 2006‐2011, P, Survival of each type of leukemia in children, adolescents, and young adults has improved dramatically over the past 30 years.

The relationship between hospital volume and patient outcome is globally known; thus, hospital volume is widely used as a quality indicator. In Japan, however, recent studies on this topic are scarce. The present study examined whether hospital surgery volume is associated with postoperative 5‐year survival among cancer patients. Using the Osaka Cancer Registry, we identified a sample of 86 145 patients who were diagnosed with cancer at any of five different sites (stomach, colorectum, lung, breast and uterus) and underwent surgeries between 2007 and 2011 in Osaka. We ranked hospitals by annual surgical volume, sorted patients in descending order by hospital volume, and assigned them into quartiles (high, medium, low and very low volume). We analyzed the association between hospital volume and 5‐year survival among 80 959 patients aged between 15 and 84 years using Cox proportional hazard models. Adjustments were made for characteristics of patients, type of surgery and adjuvant treatment received. The mortality hazard of patients treated at very low‐volume hospitals was 1.36‐1.82‐fold higher than that of patients treated at high‐volume hospitals. Absolute differences in adjusted survival rates between high‐volume and very low‐volume hospitals varied with the cancer site: 14.9 in stomach, 11.5 in colorectal, 10.8 in lung, 2.4 in breast and 3.3 in uterine cancers. Hospitals with lower surgery volumes showed higher mortality risks after cancer surgery than those with higher volumes. Monitoring site‐specific surgery volumes and referring patients from low‐volume to high‐volume hospitals may be beneficial for improving the long‐term survival of cancer patients., Postoperative 5‐year survival of 80 959 patients diagnosed with stomach, colorectal, lung, breast or uterine cancers was compared among hospitals categorized by quartiles of surgery volume, using the Osaka Cancer Registry database. Very low hospital volume was significantly associated with higher mortality hazards, whereas absolute differences in survival probability between high‐volume and very low‐volume hospitals varied with the cancer site. Monitoring site‐specific surgery volume and referring patients from low‐volume to high‐volume hospitals are recommended to improve postoperative survival of cancer patients.