Advancing Korean nationwide registry for hepatocellular carcinoma: a systematic sampling approach utilizing the Korea Central Cancer Registry database.

Hepatocellular carcinoma (HCC) presents a substantial public health challenge in South Korea as evidenced by 10,565 new cases annually (incidence rate of 30 per 100,000 individuals), in 2020. Cancer registries play a crucial role in gathering data on incidence, disease attributes, etiology, treatment modalities, outcomes, and informing health policies. The effectiveness of a registry depends on the completeness and accuracy of data. Established in 1999 by the Ministry of Health and Welfare, the Korea Central Cancer Registry (KCCR) is a comprehensive, legally mandated, nationwide registry that captures nearly all incidence and survival data for major cancers, including HCC, in Korea. However, detailed information on cancer staging, specific characteristics, and treatments is lacking. To address this gap, the KCCR, in partnership with the Korean Liver Cancer Association (KLCA), has implemented a systematic approach to collect detailed data on HCC since 2010. This involved random sampling of 10-15% of all new HCC cases diagnosed since 2003. The registry process encompassed four stages: random case selection, meticulous data extraction by trained personnel, expert validation, anonymization of personal data, and data dissemination for research purposes. This random sampling strategy mitigates the biases associated with voluntary reporting and aligns with stringent privacy regulations. This innovative approach positions the KCCR and KLCA as foundations for advancing cancer control and shaping health policies in South Korea.

Cancer Statistics in Korea: Incidence, Mortality, Survival, and Prevalence in 2021.

PURPOSE: The current study provides national cancer statistics and their secular trends in Korea, including incidence, mortality, survival, and prevalence in 2021. MATERIALS AND METHODS: Incidence, survival, and prevalence rates of cancer were calculated using the Korea National Cancer Incidence Database, from 1999 to 2021, with survival follow-up until December 31, 2022. Deaths from cancer were assessed using causes-of-death data obtained from Statistics Korea. RESULTS: The number of new cancer diagnoses in 2021 increased by 27,002 cases (10.8%) compared to 2020. In 2021, newly diagnosed cancer cases and deaths from cancer were reported as 277,523 (age-standardized rate [ASR], 289.3 per 100,000) and 82,688 (ASR, 67.6 per 100,000), respectively. The overall cancer incidence rates increased by 3.3% annually from 1999 to 2012, and decreased by 5.3% from 2012 to 2015, thereafter, followed by non-significant changes. Cancer mortality rates have been decreasing since 2002, with more rapid decline in recent years (annual decrease of 2.8% from 2002 to 2013; 3.2% from 2013 to 2021). The 5-year relative survival between 2017 and 2021 was 72.1%, which contributed to prevalent cases reaching over 2.4 million in 2021. CONCLUSION: In 2021, the number of newly diagnosed cancer patients increased as healthcare utilization recovered from the coronavirus disease 2019-related declines of 2020. Revised cancer registration guidelines expanded the registration scope, particularly for stomach and colorectal cancer. Survival rates have improved over the years, leading to a growing population of cancer survivors, necessitating a comprehensive cancer control strategy. The long-term impact of the pandemic on cancer statistics requires future investigation.

Prediction of Cancer Incidence and Mortality in Korea, 2024.

PURPOSE: This study aimed to report the projected cancer incidence and mortality for the year 2024 to estimate Korea's current cancer burden. MATERIALS AND METHODS: Cancer incidence data from 1999 to 2021 were obtained from the Korea National Cancer Incidence Database, and cancer mortality data from 1993 to 2022 were acquired from Statistics Korea. Cancer incidence and mortality were projected by fitting a linear regression model to observed age-specific cancer rates against their respective years and multiplying the projected age-specific rates by the anticipated age-specific population for 2024. A joinpoint regression model was used to determine the year in which the linear trend changed significantly; we only used the data of the latest trend for prediction. RESULTS: In total, 292,221 new cancer cases and 83,770 cancer deaths are expected to occur in Korea in 2024. The most common cancer site is expected to be the thyroid, followed by the colon and rectum, lung, breast, and stomach. These five cancers are expected to represent 55.7% of the overall burden of cancer in Korea. The most common type of cancer leading to death is expected to be lung cancer, followed by liver, colorectal, pancreatic, and stomach cancers. CONCLUSION: The age-standardized incidence rates for female breast and prostate cancers are estimated to continue to increase. These up-to-date estimates of the cancer burden in Korea could be an important resource for planning and evaluating cancer-control programs.

Changes in the Epidemiologic Pattern of Primary CNS Tumors in Response to the Aging Population: An Updated Nationwide Cancer Registry Data in the Republic of Korea.

PURPOSE: Primary CNS tumors (PCNSTs) are tumors originating from the brain and surrounding tissues. These tumors account for a significant proportion of cancer deaths and morbidity globally. Accurate epidemiologic data are essential for shaping clinical practices, research priorities, and health care policies. This study presents the latest 2020 national data on PCNSTs from the Republic of Korea (ROK) and explores the trends in incidence and their societal implications in the context of an aging population. METHODS: This is a cross-sectional, observational study conducted using data sourced from the Korea National Cancer Incidence Database by the Korea Central Cancer Registry. The study analyzed national data on PCNSTs in the ROK for the years 2010, 2013, 2016, and 2020. RESULTS: In 2020, 15,568 new PCNST cases were diagnosed in the ROK. The overall crude rate was 30.32, and the age-standardized rate was 19.37 per 100,000 persons. A decade-long trend analysis revealed an increasing trend in newly diagnosed glioblastoma and lymphoma, and a decreasing trend in embryonal tumors, in relation to the aging population of the ROK. CONCLUSION: This study shows the significant impact of demographic shifts on the epidemiologic patterns of PCNSTs in the ROK. Our findings emphasize the need for collaborative efforts to address the rising challenges posed by the changing incidence of PCNSTs related to an aging population.

Conditional Relative Survival of Exocrine Pancreatic Cancer: A Population-Based Study.

BACKGROUND: Adjusted prognostic information is important for treatment decisions, especially in elderly patients or survivors of exocrine pancreatic cancer (EPC). This study aims to investigate conditional relative survival (CS) rates and conditional probabilities of death in patients with EPC. METHODS: Data of 77,975 individuals diagnosed with EPC between 1999 and 2019 were obtained from the Korea Central Cancer Registry. CS was analyzed across strata including histology groups (ductal adenocarcinoma excluding cystic or mucinous [group I, PDAC] and ductal adenocarcinoma specified as mucinous or cystic adenocarcinoma [group II]), and age. RESULTS: For PDAC, the overall 5-year relative survival (RS) rate at diagnosis, 3-year CS of 2-year survivors, and 5-year CS of 5-year survivors were 8.5%, 50.1%, and 77.6%, respectively. Overall conditional probabilities of death were 85.2% (≥ 80 years), 73.5% (70-79 years), and 62.0% (60-69 years) in year 1 after diagnosis. Among patients with localized or regional stage who underwent surgery, conditional probabilities of death of ≥ 80, 70-79, and 60-69 years were 37.7%, 32.5%, and 22.6% in the first year, and 26.6%, 27.2%, and 26.0% in year 2 after diagnosis. CONCLUSIONS: Half of patients with EPC who survived for 2 years survived for an additional 3 years. However, 5-year PDAC survivors require follow-up as more than 20% do not survive for a further 5 years. Elderly patients should not be excluded from active treatment for localized or regional-stage PDAC, as the CS of elderly patients who are fit enough to undergo surgery is not inferior to that of younger patients.

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.

Disparities in Cancer Incidence across Income Levels in South Korea.

BACKGROUND: Recent nationwide studies of disparities in cancer incidence by income are scarce in Korea. This study investigated such disparities in cancer incidence and the stage at cancer diagnosis across income groups in Korea. METHODS: This study utilized data from a national cancer database, specifically focusing on cases recorded in the year 2018. Income levels were categorized into quintiles according to the insurance premium paid in addition to the Medicaid benefit. The slope index of inequality (SII) and relative index of inequality (RII) were used to measure absolute and relative differences in cancer incidence by income. A multivariable logistic regression was performed to estimate the risk of a distant stage at cancer diagnosis. RESULTS: The total number of cases of incident cancer was 223,371 (men: 116,320, women: 107,051) with shares of the total of 29.5% (5Q), 20.4% (4Q), 16.0% (3Q), 13.5% (2Q), 15.6% (1Q), and 5% (Medicaid). The most common cancer type was thyroid cancer, followed by gastric and colorectal cancers. The age-standardized incidence rate for all cancers was lowest in the highest income group, but the SII was not statistically significant (SII: -35.7), and the RII was -0.07. Colorectal and cervical cancers had lower incidence rates for higher income groups, while thyroid and prostate cancers had higher incidence rates for higher income groups. The odds ratio for a distant stage at diagnosis for all cancers increased for lower income groups relative to 5Q. CONCLUSIONS: Disparities in cancer incidence in a Korean population differed by cancer type, and lower income was a significant predictor of a distant stage at diagnosis for cancers overall. These results emphasize the need for further study of the underlying causes of disparities in cancer incidence and the stage at diagnosis, as well as the need for interventions to mitigate these disparities.

The Impact of Neighborhood Deprivation on the Survival Rates of Patients with Cancer in Korea.

The objective of this study is to investigate the correlation between the neighborhood deprivation index and survival rates of cancer patients in Korea. In this study, 5-year age-standardized survival rates of patients with cancer were determined using the National Cancer Cohort from 2014 to 2018 in Korea. The primary cancer sites were the stomach, colorectum, liver, lung, breast, cervix, prostate, and thyroid. Disparities were measured, and their impact on the overall survival rates was assessed using the Korean version of the Neighborhood Deprivation Index. Pearson's correlation coefficient was calculated to determine the strength of the correlation. The study cohort comprised 726,665 patients with cancer, of whom 50.7% were male. The predominant primary cancer sites were the stomach (n = 138,462), colorectum (n = 125,156), and thyroid gland (n = 120,886). Urban residents showed better survival outcomes than those situated in rural areas. The most deprived quartile had the lowest survival rate, while the least deprived quartile had the highest (p < 0.001). Most cancer types revealed significant correlations between neighborhood deprivation and 5-year age-standardized overall survival, with lung cancer showing the most substantial negative correlation (r = -0.510), followed by prostate cancer (r = -0.438). However, thyroid cancer showed only a marginal correlation (p = 0.069). The results of this study suggested that neighborhood deprivation is closely linked to disparities in overall survival across various types of cancer. A substantial negative correlation between the neighborhood deprivation index and all-cause mortality for lung and prostate cancer, as compared to breast and cervical cancers covered by the National Cancer Screening Program, may reinforce the need to address healthcare access and improve the early detection of cancer in socioeconomically deprived neighborhoods.

Incidence and survival of gynecologic cancer including cervical, uterine, ovarian, vaginal, vulvar cancer and gestational trophoblastic neoplasia in Korea, 1999-2019: Korea Central Cancer Registry.

OBJECTIVE: To investigate the incidence, trends, and survival rates of all gynecologic cancers using the Korea Central Cancer Registry (KCCR) database from 1999-2019. METHODS: Gynecologic cancer data were obtained from the KCCR database between 1999 and 2019. Age-standardized incidence rates (ASRs), annual percentage changes, and average annual percentage changes (AAPCs) were calculated. The relative survival rate (RSR) was reported by age group, stage, and 6-year period (I: 1999-2005, II: 2006-2012, III: 2013- 2019). RESULTS: The gynecologic cancer ASRs were 26.2 and 24.9 per 100,000 individuals in 1999 and 2019, respectively. Trends of incidence in gynecologic cancer revealed a decrease in cervical cancer and gestational trophoblastic neoplasia (GTN) with AAPCs of -3.4 and -4.3, respectively. Conversely, the incidence of uterine, ovarian, and vulvar cancers increased with AAPCs of 4.7, 2.3, and 2.1, respectively. AAPC for vaginal cancer showed no change. The 5-year survival rate was highest for GTN (90.5%) and lowest for vaginal cancer (56.6%). An increase in age was correlated with poorer survival rates across all gynecologic cancers, excluding vaginal cancer. For all gynecologic cancer types, the prognosis deteriorates with advancing cancer stages. The RSR of uterine cancer improved consistently across all periods. The ovarian cancer RSR improved more in period III than in periods I or II. Additionally, the vulvar cancer RSR improved more in periods II and III than in period I. CONCLUSION: In Korea, the incidence of cervical cancer and GTN decreased, whereas the incidence of uterine, ovarian, and vulvar cancer increased from 1999 to 2019. The RSR for uterine, ovarian, and vulvar cancers showed consistent improvements over different periods. Effective screening programs and the adoption of advanced treatments may be necessary to further reduce the burden of gynecologic cancer.

Regional disparities in major cancer incidence in Korea, 1999-2018.

OBJECTIVES: This study investigated regional disparities in the incidence of 8 major cancers at the municipal level in Korea during 1999-2018 and evaluated the presence or absence of hot spots of cancer clusters during 2014-2018. METHODS: The Korea National Cancer Incidence Database was used. Age-standardized incidence rates were calculated by gender and region at the municipal level for 4 periods of 5 years and 8 cancer types. Regional disparities were calculated as both absolute and relative measures. The possibility of clusters was examined using global Moran's I with a spatial weight matrix based on adjacency or distance. RESULTS: Regional disparities varied depending on cancer type and gender during the 20-year study period. For men, the regional disparities of stomach, colon and rectum, lung, and liver cancer declined, and those of thyroid and prostate cancer recently decreased, despite an overall increasing incidence. For women, regional disparities in stomach, colon and rectum, lung, liver, and cervical cancer declined, that of thyroid cancer recently decreased, despite an overall increasing incidence, and that of breast cancer steadily increased. In 2014-2018, breast cancer (I, 0.61; 95% confidence interval [CI], 0.53 to 0.70) showed a high probability of cancer clusters in women, and liver cancer (I, 0.48; 95% CI, 0.40 to 0.56) showed a high probability of cancer clusters in men. CONCLUSIONS: Disparities in cancer incidence that were not seen at the national level were discovered at the municipal level. These results could provide important directions for planning and implementing local cancer policies.

Breast Cancer Statistics in Korea, 2019.

This article provides an annual update of Korean breast cancer statistics, including the incidence, tumor stage, type of surgical treatment, and mortality. The data was collected from the Korean Breast Cancer Society registry system and Korean Central Cancer Registry. In 2019, 29,729 women were newly diagnosed with breast cancer. Breast cancer has continued to increase in incidence since 2002 and been the most common cancer in Korean women since 2019. Of the newly diagnosed cases in 2019, 24,820 (83.5%) were of invasive carcinomas, and 4,909 (16.5%) were of carcinoma in situ. The median age of women with breast cancer was 52.8 years, and breast cancer was most commonly diagnosed in the age group of 40-49 years. The number of patients who have undergone breast conserving surgery has continued to increase since 2016, with 68.6% of patients undergoing breast conserving surgery in 2019. The incidence of early-stage breast cancer continues to increase, with stage 0 or I breast cancer accounting for 61.6% of cases. The most common subtype of breast cancer is the hormone receptor-positive human epidermal growth factor receptor 2-negative subtype (63.1%). The 5-year relative survival rate of patients with breast cancer from 2015 to 2019 was 93.6%, with an increase of 14.3% compared to that from 1993 to 1995. This report improves our understanding of breast cancer characteristics in South Korea.

Risk of upper gastrointestinal cancer and death in persons with negative screening results: results from the National Cancer Screening Program in South Korea.

BACKGROUND: The Korea National Cancer Screening Program (KNCSP) offers upper endoscopy or upper gastrointestinal series (UGIS) biannually for people aged ≥ 40 years. This study aimed to assess the effect of negative screening results on the incidence of and mortality from upper gastrointestinal (GI) cancer. METHODS: A population-based retrospective cohort of 15,850,288 men and women was constructed using data from 3 national databases. The participants were followed until the end of 2017 for data on cancer incidence and in 2019 for data on the vital status. Cox proportional hazard model with time-varying exposure was used to assess the association. RESULTS: By the end of the follow-up period, 230,783 upper GI cancer cases and 99,348 upper GI cancer deaths were recorded. Negative gastric cancer screening was significantly associated with a lower risk of upper GI cancer in both UGIS (adjusted hazard ratio [aHR] = 0.81, 95% CI = 0.80-0.82) and upper endoscopy (aHR = 0.67, 95% CI = 0.67-0.68) groups. The HRs for upper GI mortality were 0.55 (95% CI = 0.54-0.56) and 0.21 (95% CI = 0.21-0.22) for the UGIS and upper endoscopy groups, respectively. The most significant reductions in the risk of upper GI cancer (UGIS: aHR = 0.76, 95% CI = 0.74-0.77; upper endoscopy: aHR = 0.60, 95% CI = 0.59-0.61) and death (UGIS: aHR = 0.54, 95% CI = 0.52-0.55; upper endoscopy: aHR = 0.19, 95% CI = 0.19-0.20) were observed among individual aged 60-69 years. CONCLUSION: Negative screening cases, especially in upper endoscopy of the KNCSP, were associated with an overall reduction in the risk of and mortality from upper GI cancer.

Prediction of Cancer Incidence and Mortality in Korea, 2023.

PURPOSE: This study aimed to report the projected cancer incidence and mortality for the year 2023 to estimate Korea's current cancer burden. Materials and Methods: Cancer incidence data from 1999 to 2020 were obtained from the Korea National Cancer Incidence Database, and cancer mortality data from 1993 to 2021 were acquired from Statistics Korea. Cancer incidence and mortality were projected by fitting a linear regression model to observed age-specific cancer rates against their respective years and then by multiplying the projected age-specific rates by the anticipated age-specific population for 2023. A joinpoint regression model was used to determine the year in which the linear trend changed significantly; we only used the data of the latest trend. RESULTS: In total, 273,076 new cancer cases and 81,818 cancer deaths are expected to occur in Korea in 2023. The most common cancer site is expected to be the lung, followed by the thyroid, breast, colon and rectum, and stomach. These five cancers are expected to represent half of the overall burden of cancer in Korea. The most common type of cancer leading to death is expected to be lung cancer, followed by liver, colorectal, pancreatic, and gallbladder cancers. CONCLUSION: The incidence rates for all types of cancer in Korea are estimated to gradually decrease. These up-to-date estimates of the cancer burden in Korea could be an important resource for planning and evaluating cancer-control programs.

Cancer Statistics in Korea: Incidence, Mortality, Survival, and Prevalence in 2020.

PURPOSE: The current study provides national cancer statistics and their secular trends in Korea, including incidence, mortality, survival, and prevalence in 2020. Materials and Methods: Incidence, survival, and prevalence rates of cancer were calculated using the Korea National Cancer Incidence Database, from 1999 to 2020, with survival follow-up until December 31, 2021. Deaths from cancer were assessed using causes-of-death data obtained from Statistics Korea. RESULTS: The number of new cancer diagnoses in 2020 decreased by 9,218 cases (3.6%) compared to 2019. In 2020, newly diagnosed cancer cases and deaths from cancer were reported as 247,952 (age-standardized rate [ASR], 262.2 per 100,000) and 82,204 (ASR, 69.9 per 100,000), respectively. The overall cancer incidence rates increased by 3.3% annually from 1999 to 2012, and decreased by 5.0% annually from 2012 to 2015, thereafter, followed by nonsignificant changes. Cancer mortality rates have been decreasing since 2002, with more rapid decline in recent years. The 5-year relative survival between 2016 and 2020 was 71.5%, which contributed to prevalent cases reaching over 2.2 million in 2020. CONCLUSION: In 2020, the number of newly diagnosed cancer patients decreased due to the coronavirus disease 2019 pandemic, but the overall trend is on the rise. Cancer survival rates have improved over the past decades. As the number of cancer survivors increases, a comprehensive cancer control strategy should be implemented in line with the changing aspects of cancer statistics. The long-term impact of the coronavirus disease 2019 pandemic on cancer statistics needs to be investigated in the future.

Five-Year Overall Survival and Prognostic Factors in Patients with Lung Cancer: Results from the Korean Association of Lung Cancer Registry (KALC-R) 2015.

PURPOSE: This study aimed to provide the clinical characteristics, prognostic factors, and 5-year relative survival rates of lung cancer diagnosed in 2015. MATERIALS AND METHODS: The demographic risk factors of lung cancer were calculated using the KALC-R (Korean Association of Lung Cancer Registry) cohort in 2015, with survival follow-up until December 31, 2020. The 5-year relative survival rates were estimated using Ederer II methods, and the general population data used the death rate adjusted for sex and age published by the Korea Statistical Information Service from 2015 to 2020. RESULTS: We enrolled 2,657 patients with lung cancer who were diagnosed in South Korea in 2015. Of all patients, 2,098 (79.0%) were diagnosed with non-small cell lung cancer (NSCLC) and 345 (13.0%) were diagnosed with small cell lung cancer (SCLC), respectively. Old age, poor performance status, and advanced clinical stage were independent risk factors for both NSCLC and SCLC. In addition, the 5-year relative survival rate declined with advanced stage in both NSCLC (82%, 59%, 16%, 10% as the stage progressed) and SCLC (16%, 4% as the stage progressed). In patients with stage IV adenocarcinoma, the 5-year relative survival rate was higher in the presence of epidermal growth factor receptor (EGFR) mutation (19% vs. 11%) or anaplastic lymphoma kinase (ALK) translocation (38% vs. 11%). CONCLUSION: In this Korean nationwide survey, the 5-year relative survival rates of NSCLC were 82% at stage I, 59% at stage II, 16% at stage III, and 10% at stage IV, and the 5-year relative survival rates of SCLC were 16% in cases with limited disease, and 4% in cases with extensive disease.

Incidence and survival rates of primary uterine carcinosarcoma in Korea: a National Cancer Registry study.

OBJECTIVE: To investigate the incidence and survival rates of primary uterine carcinosarcoma (UCS) in Korea. METHODS: From the Korea Central Cancer Registry, we identified patients diagnosed with primary UCS between 1999 and 2018 and collected their information, including age at diagnosis, Surveillance, Epidemiology, and End Results (SEER) summary stage, and treatment. Age-standardized incidence rates (ASRs) and annual percent changes (APCs) were calculated. Baseline characteristics and overall survival (OS) were compared by study periods, ages, and stages at initial diagnosis. RESULTS: Overall, the incidence rate of primary UCS increased markedly during the time period: ASRs, 0.02 per 100,000 in 1999 and 0.25 per 100,000 in 2018 (APC, 13.9%; p<0.001). No difference in OS was observed between patients diagnosed in 1999-2008 and those diagnosed in 2009-2018 (5-year survival rate, 46.0% vs. 48.6%; p=0.871). Considering the mean patient age at diagnosis of UCS, we divided the study population into 2 groups. Patients aged ≥60 years had a more frequent prior radiation history, received less multi-modality treatment, and showed worse OS than those aged <60 years (5-year survival rate, 42.7% vs. 53.6%; p=0.001). In multivariate analysis, both old age at diagnosis (≥60 years) and the SEER summary stage were identified as independent poor prognostic factors for OS, whereas radiation history before the diagnosis of UCS was not. CONCLUSION: The incidence rate of UCS in Korea increased significantly from 1999 to 2018. Advanced stage and old age (≥60 years) at diagnosis might be poor prognostic factors for survival, but not prior radiation history.

Long-term Survivorship and Non-cancer Competing Mortality in Head and Neck Cancer: A Nationwide Population-Based Study in South Korea.

PURPOSE: As the survival of head and neck cancer (HNC) improves, survivors increasingly confront non-cancer-related deaths. This nationwide population-based study aimed to investigate non-cancer-related deaths in HNC survivors. MATERIALS AND METHODS: Data from the Korean Central Cancer Registry were obtained to characterize causes of death, mortality patterns, and survival in patients with HNC between 2006 and 2016 (n=40,890). Non-cancer-related mortality relative to the general population was evaluated using standardized mortality ratios (SMRs). The 5- and 10-year cause-specific competing risks probabilities of death (cumulative incidence function, CIF) and subdistribution hazards ratios (sHR) from the Fine-Gray models were estimated. RESULTS: Comorbidity-related mortality was frequent in older patients, whereas suicide was predominant in younger patients. The risk of suicide was greater in patients with HNC than in the general population (SMR, 3.1; 95% confidence interval [CI], 2.7 to 3.5). The probability of HNC deaths reached a plateau at 5 years (5-year CIF, 33.9%; 10-year CIF, 39.5%), whereas the probability of non-HNC deaths showed a long-term linear increase (5-year, CIF 5.6%; 10-year CIF, 11.9%). Patients who were male (sHR, 1.56; 95% CI, 1.41 to 1.72), diagnosed with early-stage HNC (localized vs. distant: sHR, 1.86; 95% CI, 1.58 to 2.21) and older age (65-74 vs. 0-44: sHR, 6.20; 95% CI, 4.92 to 7.82; ≥ 75 vs. 0-44: sHR, 9.81; 95% CI, 7.76 to 12.39) had an increased risk of non-cancer mortality. CONCLUSION: Non-HNC-related deaths continue increasing. HNC survivors are at increased risk of suicide in the younger and comorbidity-related death in the older. Better population-specific surveillance awareness and survivorship plans for HNC survivors are warranted.

Estimating Age-Specific Mean Sojourn Time of Breast Cancer and Sensitivity of Mammographic Screening by Breast Density among Korean Women.

PURPOSE: High breast cancer incidence and dense breast prevalence among women in forties are specific to Asian. This study examined the natural history of breast cancer among Korean women. MATERIALS AND METHODS: We applied a three-state Markov model (i.e., healthy, preclinical, and clinical state) to fit the natural history of breast cancer to data in the Korean National Cancer Screening Program. Breast cancer was ascertained by linkage to the Korean Central Cancer Registry. Disease-progression rates (i.e., transition rates between three states), mean sojourn time (MST) and mammographic sensitivity were estimated across 10-year age groups and levels of breast density determined by the Breast Imaging, Reporting and Data System. RESULTS: Overall prevalence of dense breast was 53.9%. Transition rate from healthy to preclinical state, indicating the preclinical incidence of breast cancer, was higher among women in forties (0.0019; 95% confidence interval [CI], 0.0017 to 0.0021) and fifties (0.0020; 95% CI, 0.0017 to 0.0022), than women in sixties (0.0014; 95% CI, 0.0012 to 0.0017). The MSTs, in which the tumor is asymptomatic but detectable by screening, were also fastest among younger age groups, estimated as 1.98 years (95% CI, 1.67 to 2.33), 2.49 years (95% CI, 1.92 to 3.22), and 3.07 years (95% CI, 2.11 to 4.46) for women in forties, fifties, and sixties, respectively. Having dense breasts increased the likelihood of the preclinical cancer risk (1.96 to 2.35 times) and decreased the duration of MST (1.53 to 2.02 times). CONCLUSION: This study estimated Korean-specific natural history parameters of breast cancer that would be utilized for establishing optimal screening strategies in countries with higher dense breast prevalence.

Effect of mammography screening on the long-term survival of breast cancer patients: results from the National Cancer Screening Program in Korea.

OBJECTIVES: This study investigated the effect of mammography screening on the long-term survival of breast cancer (BC) patients aged 40 years or older according to their screening history and duration since screening. METHODS: The study cohort was organized from 3 nationwide databases of the Korean National Cancer Screening Program, the Korean Central Cancer Registry, and death certificates. We included 24,387 women diagnosed with invasive BC or ductal carcinoma in situ in 2008 and 2009 and followed up until December 31, 2019. Cox proportional-hazards regression was used to investigate the effect of BC screening on the risk of death. RESULTS: Overall, 20,916 of 24,387 patients (85.8%) were alive at the end of the follow-up period (median: 10.5 years). The long-term survival rate was significantly lower in the never-screened group (80.3%) than in the screened group (88.9%) (p<0.001). A 35% reduction in the risk of BC death (hazard ratio [HR], 0.65; 95% confidence interval [CI], 0.60 to 0.70) from screening was observed. A subgroup analysis according to the cancer stage showed 62%, 36%, and 24% lower risks of BC death for the localized stage, regional stage, and distant stage, respectively. Women aged 40-49 years received the least benefit from BC screening (HR, 0.71; 95% CI, 0.62 to 0.81). CONCLUSIONS: Mammography screening was effective in reducing the risk of BC-specific death in Asian women across all cancer stages. However, this effect was relatively small among women in their 40s, suggesting that more detailed and specialized screening strategies are needed for that age group.