Annual report of cancer statistics in Korea in

Annual report of cancer statistics in Korea in 2010 2012. 12

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Overview 1. Cancer registration in Korea 1) The Korea Central Cancer Registry (KCCR) The Korea Central Cancer Registry (KCCR) is a hospitalbased program that has been in operation since 1980. Followings are brief history of the KCCR by chronological order. - In 1980, the KCCR was started as a nationwide, hospital based program for collecting data from 47 training hospitals throughout the country. - In Sep 2000, the Headquarters of the KCCR moved from the National Medical Center to the National Cancer Center (NCC). - In May 2003, the Cancer Act was enacted. - In Dec 2004, the KCCR was designated officially as the Central registry by Ministry of Health & Welfare. - In Aug 2005, the KCCR produced the first nationwide cancer incidence statistics during 1999-2001. - In Dec 2007, the KCCR published cancer incidence rates in Korea, 2002. - In Dec 2008, the KCCR published annual report of cancer incidence and relative survival in Korea, 2003-2005. - In Dec 2009, the KCCR published annual report of cancer incidence, survival and prevalence in Korea, 2006-2007. - In Dec 2010, the KCCR published annual report of cancer incidence, survival and prevalence in Korea, 2008. - In Dec 2011, the KCCR published annual report of cancer incidence, survival and prevalence in Korea, 2009. - In Dec 2012, the KCCR published annual report of cancer incidence, survival and prevalence in Korea, 2010. 2. Data sources The data sources for the Korea National Cancer Incidence Database (KNCI DB) are the KCCR DB, the data from additional medical record review survey, the databases of the 11 population-based regional cancer registries, and the databases of sitespecific cancer registries. Death certificates are also a complementary source of information on new cancer cases. Cancer cases first identified from death certificates are tracked back to the certifying hospital. To estimate survival and prevalence, cases who diagnosed during 1993-2010 matched to vital status using the information held at the death registry at the Statistics Korea. The last follow up date was 31 December 2011

3. Classification of diseases Initially, the diagnosis of cancer was classified according to the International Classification of Diseases for Oncology 3rd edition and converted to the International Classification of Diseases 10th edition. 4. Indices of data quality 1) Completeness Completeness of registration is defined as the extent to which all the incident cancers occurring in a target population are included the registry database. The followings are several indices that were used for evaluating the completeness of the cancer registration. (1) Mortality/Incidence ratio (M/I ratio) The M/I ratio is an important indicator of data completeness. The registries are asked to provide the mortality data on cancer by sex, age group and site for the same period as the registered cases, and this data can be obtained from the local vital statistics office. When the quality of the mortality data is good, the M/I ratio is related to case fatality (1-survival). (2) Age-specific incidence curves The shape of the curve for the incidence by age is an important indicator of the possible under ascertainment. Most epithelial cancers demonstrate increasing patterns of incidence with age and since most cancers are epithelial in origin, this pattern should be observed for all sites, at least after the age of 15. 2) Validity Validity is an essential component in assessing the quality of cancer registry data. It is defined as the proportion of cases in the registry with a given characteristic (e.g. cancer sites or age) that truly have this attribute. Thus, the validity of the recorded data depends on the accuracy of data source documents and the level of skill used in abstracting, coding and recording this information for the registry database. The following are several indices to be used for evaluating the validity of cancer registry. (1) Microscopic Verification (MV) MV% is the percentage of cases for which the diagnosis was based on morphological verification of a tissue specimen. The main value of MV% is as an indicator of the validity of the diagnostic information. However, a very high proportion of cases diagnosed by histology or cytology/hematology -

higher than reasonably expected - suggests overreliance on the pathology laboratory as the source of information and failure to find the cases diagnosed by other means. (2) Death Certificate Only (DCO) Cancer cases recognized by only the mortality records were defined as DCO. DCO% is an important parameter to evaluate the quality of cancer registration data, and 15-20% is considered acceptable to get international certification. (3) Primary Site Unknown (PSU) The percentage of registrations with an unknown primary site (PSU%) is commonly monitored as an index of the diagnostic validity of the data held in the registries. 10% or more might indicate inadequate diagnostic services or the poor documentation of results. (4) Age Unknown (Age UNK) The proportion of cases registered for which the age was not known is useful as an indicator of the quality of the basic data input. In developed countries, the percentage of cases with an unknown age rarely exceeds. <Indices of data quality in Korea, 2010> (unit: %) Indices Both sexes Male Female CI5 Criteria Mortality/ Incidence ratio 35.9 44.2 27.3 30% and 70% Microscopic verification 88.5 86.1 91.0 75% Death certificate only 1.4 1.2 1.5 20% Primary site unknown 0.9 0.9 0.9 20% Age Unknown 0.0 0.0 0.0 20% Cancer Incidence In Five Continents 5. Population The population used for the rates is a mid-year population (Appendix 1). In this report, we used the average population of two consecutive years. For example, a 2010 mid-year population was estimated as (the population at the end of year 2009 + the population at the end of year 2010)/2.

6. Definitions The definitions for terms used in this report are as the following. 1) Crude Rate (CR) The Crude rate, a rate based on the frequency of cancer in the entire population, is calculated as below: Crude rate (per 100,000 person-years) = (Number of events/ corresponding person-years of observation) x 100,000 Primary cancers in one patient are included as a new case in the numerator. Although this measure is useful as an indicator of the extent of disease burden, its utility in comparing cancer risk is limited where there are differing age structures across groups. For this purpose, age-standardized rates need to be used. 2) Standard population The standard population provides age distributions to be used in the estimation of age-adjusted rates. The Korean standard population (year 2000) is used in this report. For international comparison, world standard population is used (Appendix 2). 3) Age-Standardized Rate (ASR) An age-standardized rate is a weighted average of crude age-specific rates, where the crude rates are calculated for different age groups and the weights are the proportions of persons in the corresponding age groups of a standard population. In this report, rates were standardized to the Korean standard population or the World standard population. 4) Cumulative rate (CUM) Cumulative rate is the sum over each year of age of the age-specific rates, taken from birth to age 74 for the 0-74 rate. 5) Annual Percent Change (APC) APC is a average annual percent in changes over time and expressed as (exp(b)-1)x100, where b is the estimated slope from a linear regression on logarithmic scaled age-standardized rates and calendar years. 6) Summary Stage (Young JL Jr, Roffers SD (eds). SEER Summary Staging Manual-2000, National Cancer Institute, 2001) Summary staging is the most basic way of categorizing how far a cancer has spread from its point of origin.

- Localized is a malignancy limited to the organ of origin, it has spread no farther than the organ in which it started. - Regional stage is tumor extension beyond the limits of the organ of origin. - Distant metastases are tumor cells that have broken away from the primary tumor, have travelled to other part of the body, and have begun to grow at the new location. - Unknown is that sufficient information does not exist, the case is unstageable (included death certificate only cases). 7) prevalent cases Because national cancer incidence can be estimated from 1999, prevalent cases in this report are defined as the number of cancer patients alive on a certain day who had been diagnosed with the disease since January 1, 1999. For example, cancer prevalent cases on January 1, 2011 are the cancer patients that were diagnosed between January 1, 1999 and December 31, 2010, and were alive on January 1, 2011. Multiple primary cancer cases are counted multiple times. 8) Five-year prevalent cases Five year prevalent cases are defined as the number of cancer patients alive with the disease within first 5 years from diagnosis. For example, 5-year cancer prevalent cases on January 1, 2011 are the cancer patients that were diagnosed between January 1, 2006 and December 31, 2010, and were alive on January 1, 2011. Individuals still alive at 5 years from diagnosis are considered cured. In fact, the death rates of most cancer patients 5 years after diagnosis are quite close to those expected in the general population. 9) Relative survival rates Relative survival is the ratio of survival rates of people who have a specific disease to those who don t. The percentage of survivors is usually determined at specific times, such as 1 years and 5 years after diagnosis or treatment. The survival duration of each case was determined as the time difference between the date of initial diagnosis and the date of death, date of loss to follow-up, or closing date for follow-up. Observed survival rates were calculated using a life table method and relative survival rates were estimated by the Ederer II method. 7. Cautions in interpretation Decline incidence rates after the age of 85 observed in some cancer sites may be partly due to under reporting in this age group. Quite often, elderly people are not properly examined by physicians for various reasons.

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