CONTINUING EDUCATION COLUMN J Korean Med Assoc 2017 November; 60(11):893-898 pissn 1975-8456 / eissn 2093-5951 https://doi.org/10.5124/jkma.2017.60.11.893 발생위험도에따른대장암선별전략 한동수 한양대학교의과대학소화기내과 Screening strategy for colorectal cancer according to risk Dong Soo Han, MD Hanyang University Guri Hospital, Guri-si Incidence and prevalence of colorectal cancer is increasing worldwide. It related with Westernized life style change, easier access to endoscopic facilities and organized cancer prevention program. The pathogenesis of colorectal cancer is multifactorial, most of cases are sporadic. The risk of colorectal cancer is increasing by age, sex, previous history of colon polyps and cancer, family history of colorectal cancer, hereditary colorectal cancer syndrome, and other modifiable conditions. It is best to screen with organized colorectal cancer screening program for average risk patients at the age of 50 and modify screening strategy by risk factors. Key Words: Colonic neoplasms; Screening; High risk 서론 대장암은우리나라뿐아니라전세계적으로가장빠르게발생률이증가하고있는암가운데하나이며, 예방이가능한질병자연사를가지고있는질환이다. 우리나라의 2014 년대장암연령표준화발생률은인구 10만명당남자 42.5 명, 여자 24.0명으로성별에따라전체암종가운데 2-3위를차지하고있다 [1]. 대장암은남녀모두에서발생과사망이모두증가하는추세를보인다. 여러역학자료를보면식습관의변화, 서구화된생활습관등으로인하여대장암발생률이빠르게증가하는것으로추정된다 [2]. 대장암은정상 점막에서선종이발생하고다시암종까지발생하는데일정한시간이소요된다. 따라서적절한시기에전구병변이나암종을제거하면진행병변으로이행을막아대장암에의한사망률을낮출수있다. 대장암은대부분산발성으로발생하며, 유전자변이에의한유전성대장암은비교적드물다. 고령, 남성, 대장암의가족력, 염증성장질환, 선종기왕력, 유전성대장암가계, 당뇨, 비만, 흡연등은대장암발생의위험요소가될수있으니주의하는것이바람직하다. 이글에서는대장내시경검사를중심으로한대장암의위험도에따른선별검사전략을간략하게논의해보도록한다. Received: September 3, 2017 Accepted: September 17, 2017 Corresponding author: Dong Soo Han E-mail: hands@hanyang.ac.kr Korean Medical Association This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons. org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 국내의대장암검진 국가암검진사업에대장암검진이도입되고암검진이활성 화되면서대장내시경검사의수요가빠르게증가하고있다. 대장암선별검사 893
J Korean Med Assoc 2017 November; 60(11):893-898 현행국가암검진제도에서대장암검진은평균위험도를가진 50세이상을대상으로분변잠혈검사를시행하고양성소견을보인경우대장내시경검사나대장조영술을시행할것을권고하고있다. 진료현장이나국가암검진통계자료를살펴보면분변잠혈검사후시행되는 2차검사가운데대장조영술보다는대장내시경을선호하는경향이갈수록늘어나고있다 [3]. 대장내시경검사를통해발견되는발암가능성이높은폴립을제거하면대장암의위험성을감소시킨다 [4]. 최근개정된대장암검진권고안에서는 45-80세무증상성인인경우분변잠혈검사를 1-2년마다대장암선별검사로권고하고, 대장내시경검사를개인별위험도에따라임상적판단과수검자의선호도를고려하여선택적으로시행하도록하여, 분별잠혈검사보다다소낮은등급으로권고하고있다. 실제 50세미만에서대장암환자가증가하고있지만평균적인위험도를가진무증상성인에서검진시작연령을낮추는것은다소논란이있으며, 새권고안이기존에사용하는권고안과다소상이하기때문에혼란의우려가있다. 따라서대장암의효율적인예방을위해서는무증상평균위험도를가진사람에게선기존과같은연령의체계적인선별검사를시행하고발생위험도가높은경우는상황에맞게층화하여체계적으로접근하는것이바람직하다. 대장암발생의고위험군 대장암발생의고위험군은 1) 고령및남성, 2) 이전선종성폴립의개인력과가족력, 3) 대장암의가족력, 4) 염증성장질환의기왕력이있는경우, 5) 유전성대장암, 6) 비만, 당뇨, 음주, 흡연등생활환경변화와밀접한상황이다. 1. 나이나이가증가할수록대장암의발생이늘어난다. 젊은연령에서도대장암이발생하지만대부분의대장암환자는 50세이상에서발병한다. 외국과유사하게대장암진단의호발연령은남자 64세, 여자 72세이다. 통계자료에의하면 50-64 세사이의대장암발병률은 1.4% 인반면 65세이상의발병률은 5% 를상회한다 [5]. 국내의국가암발생통계를보더라도 2014년대장암발생은 75세를정점으로연령이증가할수록계속증가하고이후감소하기시작한다 [1]. 국내의폴립관련데이터역시 50세이후폴립의유병률이증가하기때문에평균위험도를가진무증상성인에서대장암이발생하는데 5-10년이소요된다고가정하면, 50세를전후하여적절한대장암선별검사를받는것이대장암예방에가장중요하다. 대장암은이유는확실하지않으나남성에서흔히발생한다. 성비와특정부위에서발생하는대장암과의연관성이있다고알려져있으나인종에따라다른역학적소견을보인다 [6]. 2. 대장폴립대장에발생하는선종성폴립은대장암발생의위험인자이다. 그동안의역학연구를살펴보면대장내시경검사를통해선종성폴립을발견, 제거하면대장암으로인한사망률을낮출수있음이확인되었다. 하지만모든선종성폴립이대장암으로이행되는것이아니며, 과형성폴립이나 2개이하의작은선종성폴립은암화가능성이매우낮다. 따라서선별검사로대장내시경을시행하고고위험선종이발견되지않으면 10년정도뒤에검사를시행하는것이바람직하다. 혹자는발암리스크를근거로기간이길다고하지만대부분역학연구는 10년이하로단축시킬필요가없음을강조하고있다. 폴립의크기가 1 cm 이상, 융모상, 고도이형성을동반한경우, 3-10개정도존재하는경우는대장암으로발전가능성이있는고위험선종이므로 3년뒤추적검사를하는것이바람직하다. 폴립수가 10개이상인경우최초절제후 3년이내에검사를시행하는것이바람직하다. 또한조직생검에서발암가능성이높은거치상폴립으로확인된경우에도검사간격을단축시키는것이좋다 [2]. 3. 대장암의가계력또는기왕력대장암의가계력이있는경우대장암의발생위험성이증가하며혈연의정도와대장암의진단당시나이가중요하다 894 대한의사협회지
Han DJ Colon cancer screening [7]. 통상대장암환자는 10% 는부모, 형제등에서가족력이있으며, 부모, 형제가운데대장암이있으면발암확률은 2배증가한다 [8]. 하지만부모, 형제가운데 2명이상의대장암환자가있거나한명이라도 60세이전에발병한경우가있으면발암확률은 3-4배증가한다 [9]. 부모, 형제가 60세이후대장암이발생한경우발암확률은 2배미만이지만정상인보다높다 [9,10]. 밀접한친척중에대장암가계력이있으면일반적인대장암검진시작연령보다빠른 40세에시작하거나진단당시발병나이보다 10년앞서검사하는것이좋다. 부모, 형제가운데 60세이후발병한경우에도 40세에선별검사를시작하고추후에는평균위험도가있는환자의선별검사주기를따른다 [11]. 아시아환자를대상으로시행된다국가연구결과역시대장암의가계력이있으면대장암발생이 2-7배유의하게증가하며, 부모와형제사이의비교위험도는비슷하였다 [11]. 본인이대장암을앓았을경우전체대장을확실하게확인하는것이중요하다. 대장암수술후수술전장관폐쇄등으로대장내시경검사가제대로이루어지지않은경우절제술후 3-6개월이내에동시성병변을배제하기위해검사를시행한다. 또한대장암으로근치절제술을받은경우술후 1년후에추적내시경검사를시행하는것이좋다. 이후검사일정은일반적인검사권고안과동일하다 [12]. 4. 염증성장질환을오래앓은경우궤양성대장염을앓고있는경우염증의유병기간과침범범위, 염증의심한정도에따라발암확률이증가한다. 흔히 10년이상궤양성대장염을앓고있거나원발성경화성담관염을동반하는경우, 성인이전에발병한경우에발암가능성이증가한다 [13]. 물론병변의범위에따라다르지만적어도 8년이상궤양성대장염을앓고있는경우대장내시경검사를권고하는것이좋다. 크론병역시증상이발생후 6-8년이경과하면대장내시경검사를시행하는데대장에염증이존재하는지유무에따라검사간격을 3-5년단위로조절한다. 협착이있거나이전에이형성, 원발성경화성담관염의기왕력, 대장암의가계력등이있으면검사 간격을더단축하여추적하는것이바람직하다 [14]. 대장암예방을위한염증성장질환환자의추적검사는과거일정한간격으로대장점막생검을하는것이대세였으나, 최근다양한방법을이용한목표생검검사의유용성이보고되고있다 [15,16]. 5. 유전성대장암또는비유전성대장암유전성대장암은대장암가운데 5% 내외를차지한다. 특징적인임상상때문에적절한시기에대장내시경이나유전자검사를통해계획된장절제를할경우본인뿐아니라다른가족구성원의대장암에대한위험성을줄일수있다. 유전성대장암에는잘알려진 Lynch증후군, 가족성용종증외에도포이츠예거증후군 (Peutz Jeghers syndrome), Cowden증후군, 유소년용종증, 거치상폴립증등다양한종류가있다 [17]. Mismatch repair 유전자의이상과연관있는유전성비용종성대장암인 Lynch증후군이의심되는경우 mismatch repair 유전자의돌연변이검사를받아보는것이좋고, 가족은 20-25세때부터매 2년간격으로대장내시경검사를받는것이좋다. 만일유전자검사에서돌연변이유전자를보유하는것이확인된경우매년내시경검사를시행하여야한다. 아울러 30-35 때부터산부인과검사를시행하여부속기에종양이발생하는지확인한다 [18]. APC유전자의변이에의한가족성용종증은다발성선종이사춘기때부터나타난암화과정이진행된다. 따라서사춘기시작때부터 S자결장경이나대장내시경검사를시행하거나유전자검사를해보는것이좋다. 이외에도 25세전후부터정기적으로위내시경검사나매년갑상선검사를시행하는것이좋다. 거치상폴립증의경우모든폴립을제거하고일반적인선종보다빠르게 1-3년간격으로대장내시경검사를하는것이바람직하다. 6. 생활인자생활인자에따라대장암의위험도또한증가한다. 통상신체활동이제한된경우, 고지방식식이, 과체중과비만, 음주, 흡연등이대장암발생의위험인자이다 [19]. 체계적문헌분석을통해보면흡연이의미있게대장암발생을증가시키 대장암선별검사 895
J Korean Med Assoc 2017 November; 60(11):893-898 며, 특히흡연기간이길수록직장암발생이많아진다 [20]. 과도한음주역시대장암발생을증가시키는데사회적인음주를할경우위험도가높아지지않지만음주량이증가할수록대장암발생이많아진다 [21]. 유사하게당뇨나비만등이있으면대장암의위험성이증가한다 [22]. 국내환자나인종적배경이유사한아시아권환자를대상 시적인점검이아니라현실적이고지속적으로질관리가되도록체계적인프로그램의도입이필요하다 [25]. 외국에서시행하는질관리프로그램이좋은예라고할수있다. 제대로질관리가이루어지지않는대장내시경검사는결국불필요한추적검사를유발하게되어의료자원을낭비할뿐아니라중간암의위험성을증가시킨다 [26]. 으로한연구를살펴보면대상환자의연령, 성, 가족력, 흡 연기왕력을수학적알고리즘을통해이용하면무증상성인에서대장암이나고위험선종의위험성을예측할수있다 [23]. 또한국내에서시행된다른연구에서도대장암의적정선별연령이아닌 45-49세연령에서, 남자, 고지방혈증, 저 HDL (high density lipoprotein) 혈증농도는진행성대장암발생에중요한영향을주는인자임을알수있다 [23]. 따라서대장암발생위험도가높은경우무증상평균위험도의검사시기보다당겨서검사를진행하는것이바람직하다. 결론 빠르게증가하는대장암을예방하기위해서는대장암발생의평균위험군을가진사람에서 50세를기준으로체계화된국가암검진제도를이용하여검진을하는것이바람직하고, 발생위험성이높은사람은각각위험요소에적절한선별검사전략을세워야한다. 아울러대장암예방에가장초 석이되는대장내시경검사는질관리가철저히되어불필요 질관리가뒷받침된대장내시경검사 한추적검사를양산하는일이없어야한다. 대장내시경검사는대장암검진에서가장중요한역할을 찾아보기말 : 대장암 ; 선별검사 ; 고위험군 차지한다. 하지만시술자에따라대장내시경검사결과가차 이가난다는것은이미잘알려진사실이다. 적정하게질관 리가이루어진대장내시경검사는점막표면을잘관찰할수 ORCID Dong Soo Han, http://orcid.org/0000-0001-7103-3318 있도록장정결이이루어져야하며, 시술자의맹관삽입률이 95% 이상정도로충분한수련을받은의사에게시행받아야한다. 검사후에는맹관삽입을증명하는회맹부구조가잘드러난사진이남아야하며, 삽입하는시간이외에많은시간을관찰에할애하여회수하며관찰하는시간을최소한 6 분이상관찰하면서선종발견율을높이는것이중요하다. 한편선종발견율은평균 25% 가넘을것을여러학술단체에서요구하고있다 [24]. 현행시행되는국가암검진질관리프로그램에서도이와같은점을강조하고있다. 장정결정도와시술자에따라선종발견율이많이차이가나는점, 검사관찰시간이길수록선종발견율이높아지는점등을고려할때시술자는선종발견율을향상시키도록노력해야한다. 질관리프로그램역시일 REFERENCES 1. Jung KW, Won YJ, Oh CM, Kong HJ, Lee DH, Lee KH; Community of Population-Based Regional Cancer Registries. Cancer statistics in Korea: incidence, mortality, survival, and prevalence in 2014. Cancer Res Treat 2017;49:292-305. 2. Levin B, Lieberman DA, McFarland B, Andrews KS, Brooks D, Bond J, Dash C, Giardiello FM, Glick S, Johnson D, Johnson CD, Levin TR, Pickhardt PJ, Rex DK, Smith RA, Thorson A, Winawer SJ; American Cancer Society Colorectal Cancer Advisory Group; US Multi-Society Task Force; American College of Radiology Colon Cancer Committee. Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. Gastroenterology 2008;134:1570-1595. 896 대한의사협회지
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