cancer is the leading cause of death in korea , where more than 73,757 people died of cancer in 2012 . the cancer incidence rate for all cancer sites combined increased by 3.4% per year ( 1.6% in males , 5.4% in females ) from 1999 to 2011 . cancer screening allows for early cancer detection , before appearance of symptoms , which usually results in better outcomes . therefore , screening reduces cancer mortality , and in some cases , cancer incidence . in korea , both organized and opportunistic cancer screening are available . opportunistic cancer screening programs include a variety of options in terms of the items screened , intervals between screenings , and target cancer type depending on individual decisions or recommendations from health care providers . in 1999 , the korean government established the national cancer screening program ( ncsp ) to provide organized cancer screening to reduce the burden of cancer . since then , the target population and types of cancer covered by ncsp have been expanded . the ncsp provided medical aid recipients with free - of - charge screening for stomach , breast , and cervical cancer until 2001 . since 2002 , national health insurance ( nhi ) beneficiaries in the lower 20% income stratum have been included in the ncsp . in 2003 , nhi beneficiaries in the lower 30% income stratum and patients with one additional type of cancer ( liver ) were included , and patients with colorectal cancer were included in the ncsp in 2004 . since 2005 , the ncsp has provided medical aid recipients and nhi beneficiaries in the lower half of the income stratum with screenings for five types of cancer ( i.e. , stomach , liver , colorectal , breast , and cervix uteri ) . nhi beneficiaries in the upper 50% income stratum receive screening services for the same five types of cancer from the nhi corporation ; however , they pay 10% of the screening cost [ 3 - 7 ] . the ncsp utilizes nationally implemented protocols that define a target population , screening interval , and follow - up strategies ( table 1 ) . here , we report the trends in overall screening rates associated with both the organized and opportunistic cancer screening programs among korean men and women , and we evaluate policies on cancer screening programs implemented to reduce the burden of cancer . the korean national cancer screening survey ( kncss ) data from 2004 to 2013 were used in the current study . stratified multistage , random sampling based on resident registration population data are collected according to geographical area , age , and sex . in the current study , the number of enumeration districts was designated in proportion to population size by sex , age , and geographical area , and the final study clusters were randomly selected . a total of 5 to 7 households in an urban area , and 10 to 12 households in a rural area were randomly chosen . the methods used for sampling were described in a previous study . according to the protocols of the ncsp ( table 1 ) , people older than 40 years of age are eligible to undergo gastric cancer screening ; those older than 50 years of age are eligible to undergo colorectal cancer screening ; women older than 40 years of age are eligible to undergo breast cancer screening ; and women older than 30 years of age are eligible to undergo cervical cancer screening . screening for liver cancer is restricted to individuals older than 40 years of age , in high - risk groups , such as patients who were carriers of hepatitis b virus or hepatitis c virus , or who have liver cirrhosis . therefore , the target population in the current study comprised cancer - free men and women older than 40 and 30 years of age , respectively , in each year from 2004 to 2013 . in 2004 , the data were collected using computer - assisted telephone interviews . from 2005 to 2013 , the data were collected through face - to - face interviews conducted by a professional research agency . subjects were recruited through door - to - door contact , and at least three attempts to contact each household were made . one person was selected from each household ; if there was more than one eligible person in the household , the person whose date of birth was closest to the study date was selected . the response rates ranged from 34.5% to 69.3% from 2005 to 2013 . using a structured questionnaire , participants were asked about their experience with screening for five types of cancer ( i.e. , stomach , liver , colorectal , breast , and cervix uteri ) and sociodemographic characteristics , including income level . the distributions of the sociodemographic characteristics of the study respondents for each year are shown in table 2 . the questions included  have you ever undergone [ cancer type ] screening ?  and  which screening method have you experienced ?  for the interval between screenings , the question was as follows :  when did you last undergo [ cancer type ] screening with this method ?  to determine the reasons for undergoing or not undergoing screening , we asked lifetime screening  was defined as having ever undergone each type of screening test during his or her lifetime . the  screening rate with recommendation  category was assigned to participants who had undergone screening tests according to the procedure and interval of the ncsp ( table 1 ) . however , for colorectal screening , respondents who underwent colonoscopy , double - contrast barium enema ( dcbe ) , or fecal occult blood test ( fobt ) within 5 , 5 , or 1 year , respectively , before 2009 , and within 10 , 5 , and 1 year , respectively , after 2009 were considered to have undergone screening with recommendation . changes in the annual screening rates for lifetime screening and screening rates with recommendation were calculated as the annual percentage change ( apc ) within a 95% confidence interval ( ci ) . the screening rates of each of the four cancers ( stomach , colorectal , breast , and cervix uteri ) were also calculated according to sex , age , and income . because of an inadequate number of individuals within the high - risk group and unstable results that showed a wide 95% ci , the liver cancer screening rate was excluded from subgroup analysis . this study was approved by the national cancer center institutional review board in korea ( approval number : nccncs-08 - 129 ) . the lifetime screening rates and screening rates with recommendation increased from 2004 onward . from 2004 to 2013 , the lifetime screening rates increased annually by 3.9% for gastric cancer , 1.8% for liver cancer , 5.0% for colorectal cancer , 3.4% for breast cancer , and 0.3% for cervical cancer ( table 3 ) . significant increasing trends were observed in the lifetime screening rates for gastric , colorectal , and breast cancer , but not for liver or cervical cancer . the screening rates with recommendation increased annually by 4.2% for gastric cancer , 1.2% for liver cancer , 3.0% for colorectal cancer , 3.7% for breast cancer , and 1.3% for cervical cancer from 2004 to 2013 . significant increasing trends were observed in the screening rates with recommendation for all types of cancer . the trends and the apc of the screening rate differed according to the screening method used . the screening rate using upper endoscopy increased by more than 2-fold compared to that using an upper gastrointestinal series ( 4.2% and 1.7% per year , respectively ) . the colorectal cancer screening rate using fobt or colonoscopy showed a more rapid increase than that using dcbe ( 2.7% , 2.2% , and 0.2% per year , respectively ) . only the screening rate with recommendation using dcbe increased without statistical significance . the screening rates according to sex , age , and income were calculated ( table 4 , figs . the screening rate with recommendation for stomach and colorectal cancer showed a steady increase ( fig . increasing trends were observed for stomach , colorectal , and cervical cancer from 2004 onward . for breast cancer , despite an increase in the screening rate with recommendation until 2012 , the screening rate decreased rapidly by 11.2% from 2012 to 2013 . for stomach and colorectal cancer , the screening rates with recommendation an increasing tendency was observed before 2012 , and the screening rate decreased from 2012 to 2013 in all age groups . the most rapid decrease in the screening rate with recommendation occurred for patients in their fifties with breast cancer in 2013 ( 18.3% ) . although the screening rate with recommendation for cervical cancer in 2004 showed a significant difference according to age ( highest rate , 70.5% vs. lowest rate , 27.9% ) , the screening rates by age group were similar in 2013 . the screening rates for stomach and colorectal cancer increased steadily at all income levels , and differences in screening rates were smaller among all income groups than those in 2004 ( fig . 3 ) . screening rates for breast cancer showed an increasing pattern from 2004 to 2012 , followed by a decreasing pattern in all income groups . the screening rate for cervical cancer was lower in the low - income group than in the middle- and high - income groups , whereas differences between groups showed a decrease . both the lifetime screening rates and screening rates with recommendation for the five above - mentioned cancers have increased since 2004 . the lifetime screening rates for all cancer types with the exception of liver cancer exceeded 70% in 2013 . the screening rates with recommendation are smaller than lifetime screening rates for each cancer . repeated screening with the optimal time interval is required for early detection of cancer . the screening rates with recommendation for gastric and breast cancer exceeded 70% in 2012 , but those for breast cancer decreased to 59.7% in 2013 . for breast cancer , the screening rate with recommendation increased by approximately 10% from 2011 to 2012 , and declined by more than 10% from 2012 to 2013 . in 2013 , the screening rate with recommendation for breast cancer showed a trend similar to that in 2010 and 2011 . the decreasing screening rates for breast cancer in all age groups appear to be the effect of broadcasted negative messages about breast cancer screening since 2012 in korea . also , in case of cervical cancer , the screening rate with recommendation for patients in their fifties decreased by 10.8% from 2012 to 2013 . therefore , continuous surveys and observations are needed to determine whether the decrease since 2012 will continue to be steady or is only a temporary decrease . the trends of changes in cancer screening rates were analyzed by socio - demographic factors associated with cancer screening rate . the gaps of screening rates have recently decreased among age groups , and household income status in most of five cancers in ncsp . these trends suggested the positive effects in reducing the inequity regarding cancer screening by ncsp in korea . in the united states , the guide to community preventive services conducted and updated systematic reviews on the effectiveness of interventions to increase the screening rates for breast , cervical , and colorectal cancers . this group recommends interventions involving one - on - one client education , providing client reminders , making screening more accessible and easier , reducing out - of - pocket costs , and performing provider assessment and feedback . client reminders , increasing community access to screening , reducing out - of - pocket costs , and performing provider assessment and feedback have already been implemented in the korean ncsp . however , the introduction of group or one - on - one education to clients should also be considered in korea . previous studies conducted in japan reported a very high correlation between cancer screening rates and sending personal invitation letters regarding the strategies used in japan . sending personal invitation letters has already been implemented in the ncsp system . in the united kingdom , where nationwide organized cancer screening has been implemented , the national health system ( nhs ) breast screening program provides mammographic breast screening every 3 years . the 3-year coverage for breast cancer screening was 73.4% for women aged 45 to 74 years who underwent mammography in 2010 - 2011 . in the united states , based on the national health interview survey , the breast cancer screening rate using mammography among women aged  40 years was 51.2% , 53.0% , and 51.0% in 2005 , 2008 , and 2010 , respectively . before 2005 the screening rates for breast cancer in korean women in the same year were lower than those reported . in japan , the screening rate for breast cancer was 14.2% in 2007 , trending toward a gradual increase since the early 1990s . in the united kingdom , the 5-year cervical cancer screening coverage using the pap smear test was 79.0% for women aged 25 to 49 in 2011 - 2012 . however , there was a small drop in the 5-year coverage for women aged 50 to 64 years from 78.0% between 2010 and 2011 , to 77.8% between 2011 and 2012 . based on the national health interview survey conducted in the united states , the screening rate for cervical cancer in american women aged  18 years , who reported having undergone a pap test within the past 3 years , was 79.6% , 78.3% , and 76.4% in 2005 , 2008 , and 2010 , respectively . no changes in the absolute differences in the rates of cervical cancer screening according to education were observed . the rates in the united kingdom and united states were higher than those reported in the same year in korea . in japan , the screening rate for cervical cancer was 18.8% in 2007 , lower than that reported in korea . in korea , both the lifetime screening rate and the screening rate with recommendation for colorectal cancer have shown a steady increase since 2004 . in addition , the screening rate for colorectal cancer using fobt or colonoscopy showed a more rapid increase than that using dcbe . based on the national health interview survey conducted in the united states , the prevalence of recent screening with either fobt or endoscopy was 43.1% in 2005 , 50.2% in 2008 , and 56.4% in 2010 . these rates are higher than those reported in the same year in korea . in korea , similar total colorectal cancer screening rates were reported for fobt and colonoscopy , while in the united states a much higher screening rate was reported for colonoscopy than fobt . in japan , the screening rate for colorectal cancer was 18.8% in 2007 , trending toward a gradual increase ( apc , 0.5% ) since the early 1990s . the kncss conducted a 10-year nationwide survey in korea and reported the screening rates for five types of cancer . this study used self - reported data , which might have been affected by recall bias . however , many studies have reported high correlations between the rates derived from chart audits and patient surveys [ 20 - 22 ] . in addition , the response rate in this study ranged from 34.5% to 69.3% . however , our response rate can be considered acceptable compared to other nationwide studies conducted in korea , in which the response rates were greater than 50% . in the current study , we used stratified multistage , random sampling according to geographical area , age , and sex , but not considering the economic level distribution . despite some limitations , this nationwide , annual therefore , the data were sufficiently representative for investigation of the changes of cancer screening rates . the korean government implemented the 10-year plan for cancer control ; the first term was conducted from 1996 to 2005 , and the second term from 2006 to 2015 . one of the goals of the second term of the 10-year plan for cancer control was achievement of a 70% cancer screening rate with recommendation . in the current study , the screening rate with recommendation for stomach cancer exceeded 70% after 2012 , and the screening rate for cervical cancer was close to reaching that goal . however , the screening rates for liver , colorectal , and breast cancer were lower than that goal in 2013 . the kncss is conducted for systematic collection , analysis , and interpretation of data regarding the planning , implementation , and evaluation of nationwide cancer screening policies in korea . as a result of these efforts , the screening rates for five types of cancer have shown a steady increase since 2004 , the gaps of cancer screening rates according to socio - demographic factors have decreased , and those for some types of cancer have reached the goal of the 10-year plan for cancer control .
purposethe korean national cancer screening survey ( kncss ) , a nationwide cross - sectional survey , has been conducted annually since 2004 . 
 the current study was conducted to report on the trends in screening rates among korean men and women , and to evaluate policies regarding cancer screening programs implemented to reduce the burden of cancer.materials and methodsthe current study used kncss data . 
 the eligible study population included men aged 40 - 74 years and women aged 30 - 74 years with no cancer history . 
 the lifetime screening rate , screening rate with recommendation , and changes in annual rates were calculated for five major cancers ( i.e. , stomach , liver , colorectal , breast , and cervix uteri).resultsthe screening rates with recommendation increased by 4.2% ( 95% confidence interval [ ci ] , 3.7% to 4.8% ) annually for stomach cancer , 1.2% ( 95% ci , 0.1% to 2.4% ) for liver cancer , 3.0% ( 95% ci , 1.8% to 4.1% ) for colorectal cancer , 3.7% ( 95% ci , 2.7% to 4.8% ) for breast cancer , and 1.3% ( 95% ci , 0.8% to 1.8% ) for cervical cancer . in 2013 , 
 the screening rates with recommendation for stomach , liver , colorectal , breast , and cervical cancers were 73.6% , 33.6% , 55.6% , 59.7% , and 67.0% , respectively.conclusionboth the lifetime screening rates and screening rates with recommendation for the five above - mentioned cancers increased annually from 2004 to 2013 .