딥페이크와 사생활 보호

고세일 한국재산법학회 2025 재산법연구 Vol.42 No.1

한 사람이 쓰는 컴퓨터가 한 공간에 남아 있었다. 그 사람이 쓰는 컴퓨터는 다른 사람이나 다른 사람이 쓰는 컴퓨터와 연결되지 않았다. 시간이 흘러서 인터넷이 도입되었다. 전화선, 케이블선, 랜선을 통해서 인터넷으로 여러 컴퓨터와 연결되었다. 많은 사람 사이에 많은 정보가 오고 갔다. 인터넷 이전의 세상과 인터넷 이후의 세상이 많이 달라 보였다. 또한 시간이 흘러서 인공지능이 나타났다. 많은 사람은 인공지능이 새로운 산업혁명을 일으킬 것으로 여기고 열광하기도, 두려워하기도 했다. 또한 다른 시간이 흘러서 생성형 인공지능이 등장했다. 많은 사람은 생성형 인공지능의 똑똑함에 놀랐다. 많은 사람은 생성형 인공지능을 신기한 것으로 여겼다. 또한 생성형 인공지능이 만들어 내는 그림자에 대해서도 고민하기 시작했다. 생성형 인공지능이 만드는 어두운 그림자 가운데 한 영역이 딥페이크이다. 현실에서 딥페이크가 문제를 일으키는 영역은 크게 둘이다. 첫째는 ‘선거’와 관련된 영역이다. 둘째는 ‘음란물’이다. 딥페이크가 우리 사회에 부작용을 일으키는 두 영역의 공통점은 사람의 동일성(identity)을 침해한다는 점이다. 다른 사람이 나쁜 의도로 어떤 사람의 이미지에 대한 동일성을 깨뜨린다. 딥페이크 기술로 만든 나쁜 이미지가 그 사람의 진실한 이미지를 왜곡한다. 그러면서 그 사람에 대한 나쁜 이미지로 그 사람의 진실한 이미지를 대체한다. 따라서 대중은 딥페이크 기술로 만들어진 나쁜 이미지를 그 사람에 관한 참된 정보로 인식한다. 그런 면에서 딥페이크는 그 사람에 대한 동일성을 왜곡하고, 그 사람에 대한 자아상(self-image)을 허문다. 딥페이크가 일으키는 측면을 다루는 논문은 두 방향성으로 접근한다. 첫째는 딥페이크에 대한 기술적 측면을 고찰하는 논문이다. 둘째는 딥페이크를 형사법적으로 규율하려고 탐구하는 논문이다. 그런 측면에서 아직 딥페이크에 대한 민사법적 접근의 논문은 시작 단계이다. 딥페이크를 법으로 규율하는 영역을 모두 망라하면, 이는 ① 플랫폼 책임, 잠재적 인공지능 개발자의 책임을 규율하는 행정법 영역, ② 형사법 영역, ③ 명예훼손과 사생활 침해를 규율하는 민사법 영역이다. 이 논문에서는 딥페이크에 대한 민사법적 접근으로, 딥페이크와 관련한 사생활 보호에 초점을 둔다. 글쓴이는 이 논문을 다음과 같이 구성한다. 먼저 II에서 딥페이크가 일으켰던 사례와 딥페이크 기술을 설명한다. 그 뒤에 III에서 딥페이크에 대한 법적 규율로 사생활 보호를 고찰한다. 마지막으로 IV에서 딥페이크가 일으키는 사생활 문제를 어떤 측면에서 규율하고 보호할 것인지에 대해서 제언한다. A person uses their computer in their space. Their computer is not connected to other computers. As time passed, the Internet was introduced. Many computers became connected to the Internet through telephone, cable, and LAN lines. A wealth of information was exchanged among many people. The world before and after the Internet was different. Additionally, as time progressed, artificial intelligence emerged. Many were excited or afraid that artificial intelligence would bring about a new industrial revolution. Moreover, as time continued, generative artificial intelligence arrived. Many people were astonished by the capabilities of generative artificial intelligence. Many thought generative artificial intelligence was incredible. However, they also began to worry about the shadows that generative artificial intelligence makes. One aspect of the dark shadow that generative artificial intelligence casts is “deepfakes.”In reality, there are two significant areas where deepfakes cause problems. The first is related to “elections.” The second is “pornography.” The commonality between the two regions is that deepfakes adversely affect our society because the new technology violates human identity. Tortfeasors intend to undermine a person’s image and identity. Deepfakes create harmful images and distort a person’s actual representation. Subsequently, these distorted images replace the authentic representation. As a result, the public perceives the harmful images created using deepfake technology as accurate information about the person. In this sense, deepfakes distort a person’s identity and damage their self-image. Thus, various academic journals have addressed deepfakes using two main approaches. One focuses on the technical aspects of deepfakes, while the other examines their regulation under criminal law. In this context, academic articles discussing civil responsibility related to deepfakes are still in the early stages. When considering all areas that legislate deepfakes, there are (1) administrative law regulating the responsibilities of platform providers and potential AI developers, (2) criminal law, and (3) civil law governing defamation and invasion of privacy. In this article, the author concentrates on privacy protection concerning deepfakes, based on civil responsibility. This article is organized as follows: First, in section II, the author explains the cases arising from deepfakes and deepfake technology. Then, in section III, the author examines privacy protection as a legal regulation for deepfakes. Finally, in section IV, the author proposes measures to protect privacy from deepfakes.

불법행위의 예견가능성과 손해배상범위에 대한 연구 – 민법 제763조의 준용에 따른 민법 제393조의 해석문제 –

고세일 한국민사법학회 2014 民事法學 Vol.66 No.-

Historically the current Korean Civil Code has been succeeded by European Civil Codes, especially the German and French Civil Code through Japan. In aspect of non-performance and torts liability, Korea has imported general provisions, articles 390 and 750 of the Korean Civil Code from the French Civil Code. In the meanwhile the drafters had not enough time to make the Korean Civil Code, due to historical incidents. Therefore, there have been new provisions in the present Korean Civil Code for which interpretations have been difficult, because they had not been in the earlier Korean Civil Code. One of these tricky provision is article 763 of the Korean Civil Code, by which the article 393 (Scope of Damages in Non-performance) may be applicable by mutatis mutandis to tort claims. In this regard, drafters of the Korean Civil Code had attempted to treat the scope of tort damages as same as that of breach of contracts. However the provision which has treated scope of tort damages as same as that of non-performance, like the article 763 has hardly found in any other comparative laws. Therefore there have been controversies such as pros and cons of the current article 763. In this aspect, this author attempts to examine where the article 763 of the Korean Civil Code had come from in legal historical and comparative perspectives. This article has mainly six parts. In II, this author attempts to look into comparative examples of article 763 of the Korean Civil Code, and then explains the historical origin of the controversial provision. In III, this author studies English Hadley v. Baxendale, which has influenced the foreseeability rule in breach of contract world-widely. In IV, this author examines American Palsgraf v. Long Island Railroad, which may be a historical starting point for the foreseeability rule of torts. In V. this author reviews provisions of foreseeability rules in American Restatements (Second and Third) of Torts. In VI, this author examines foreseeability rule of Principles of European Tort Law and Non-Contractual Liability Arising out of Damage Cause to Another in European perspective. Finally while summarizing foreseeability rules of Hadley, Palsgraf, American Torts Restatements, and European discussions, this author attempts to mention why mutatis mutandis of article 393 in article 763 of the Korean Civil Code may be abrogated and a new provision for scope of torts damages may be necessary.

Roman Iniuria and its influence on modern legal system - Is it a foundation of Right of Personality?

고세일 충남대학교 법학연구소 2007 法學硏究 Vol.18 No.2

운동경기에 참가하는 사람의 주의의무에 대한 고찰 : - 미국 법원의 운동경기에 참여한 사람의 주의의무 판단을 중심으로 -

고세일 忠南大學校 法學硏究所 2021 法學硏究 Vol.32 No.2

When participating in athletic games, there have been risks in which participants may be injured by activities of other participants. If normal injuries have occurred, the player may consider that he or she should bear his or her injuries. However, if severe injures have come in the course of sports activities, the circumstances would be different. The sports player would not willingly take his or her injures, if the harms have been beyond its ordinary expectation. Several media have reported the Supreme Court’s decision sentenced on January 31, 2019, 2017 Da203596, and the Korean public have paid attention to the Court’s ruling. The first trial and the Supreme Court concluded that the defendant was not responsible for the goalkeeper’s injuries. On the other hand, the second trial court ruled in favor of some of the injured soccer player. In this article, this author has examined the duty of care of those who have participated in sports games. This article was made up of all five. In II., this author has summarized the facts and court’s judgments and their legal grounds. In III., this author has sought to find “safety care duty,” in structure of obligations and to categorize the Korean Supreme Courts’ cases concerning the safety care duty. In IV., this author has studied US courts cases which have occurred in sports and recreation games for a comparative legal viewpoint of duty of care. In V., this author has summarized and attempt to provide directions for which we may need to look for. 운동경기에 참여할 때 크고 작은 부상의 위험이 있다. 작은 부상인 경우에는 놀다가 다친 것으로 여길 수 있다. 그렇기 때문에 참가자가 스스로 그 부담을 져야 한다는 인식이 있다. 그런데 운동경기에 참여하여, 예상하지 못한 큰 부상을 입을 때 상황이 달라진다. 참가자가 그런 큰 부상을 일으킨 상대방 참가자에게 손해배상책임을 묻고자 한다. 여러 언론이 대상 판결인 대법원 2019. 1. 31. 선고 2017다203596 판결을 보도했고, 일반인도 이 사안에 큰 관심을 가졌다. 1심과 대법원은 피고에게 책임이 없다는 점에서 결론을 같이 했다. 반면에 2심인 고등법원은 원고 일부 승소 판결을 내렸다. 이 글에서는 대상 판결을 중심으로 운동경기에 참가하는 사람의 주의의무를 살펴본다. 이 글은 모두 다섯 부분으로 이루어졌다. II.에서는 대상판결의 사실관계와 법원의 판단 내용을 살핀다. III.에서는 대상 판결이 운동경기에 참가하는 사람의 주의의무의 주된 논거로 삼는 ‘안전배려의무’의 뜻과 안전배려의무에 대한 여러 유형의 대법원 판례를 검토한다. IV.에서는 운동경기에 참여한 사람의 주의의무를 검토하기 위해서 운동경기에서 발생한 사안이 많은 미국 판례 내용을 고찰한다. V.에는 지금까지 내용을 정리하고, 시사점을 제시한다.

Is There a Role for Adjuvant Therapy in R0 Resected Gallbladder Cancer?: A Propensity Score-Matched Analysis

고세일,김영생,황인규,김은영,오성용,지준호,송하나,박세훈,박준오,강정훈 대한암학회 2016 Cancer Research and Treatment Vol.48 No.4

Purpose The purpose of this study is to assess the role of adjuvant therapy in stage I-III gallbladder cancer (GBC) patients who have undergone R0 resection. Materials and Methods Clinical data were collected on 441 consecutive patients who underwent R0 resection for stage I-III GBC. Eligible patients were classified into adjuvant therapy and surveillance only groups. Propensity score matching (PSM) between the two groups was performed, adjusting clinical factors. Results In total, 84 and 279 patients treated with adjuvant therapy and followed up with surveillance only, respectively, were included in the analysis. Before PSM, the 5-year relapse-free survival (RFS) rate was lower in the adjuvant therapy group than in the surveillance only group (50.8% vs. 74.8%, p < 0.001), although there was no statistically significant difference in the 5-year overall survival (OS) rate (66.2% vs. 79.5%, p=0.089). After the PSM, baseline characteristics became comparable and there were no differences in the 5-year RFS (50.8% vs. 64.8%, p=0.319) and OS (66.2% vs. 70.4%, p=0.703) rates between the two groups. Conclusion The results suggest that fluoropyrimidine-based adjuvant therapy is not indicated in stage I-III GBC patients who have undergone R0 resection.

아편유사제의 안전한 사용

고세일,원영웅,강정훈 대한의사협회 2022 대한의사협회지 Vol.65 No.1

Background: Opioids are effective analgesics for cancer pain and refractory non-cancer pain. Although they are essential medication, problematic issues on aberrant behavior and adverse events have rapidly emerged as social problems in Korea. This study aimed to describe the mechanisms, efficacy, and adverse events, especially how to deal with opioid dependency. Current Concepts: Opioid-induced aberrant behavior includes physical and psychological dependences (addiction), abuse, and diversion (giving prescribed opioids to another person). Most physicians are unfamiliar with how to handle patients presenting these problematic issues. Physical and psychological dependences develop through different pathophysiologic mechanisms, i.e., noradrenergic and dopaminergic pathways, respectively. Motivational enhancement therapy, psychosocial support, substitution therapy with buprenorphine, and adjunctive medications, including alpha-2 adrenergic agonist, antidepressants, and non-steroidal antiinflammatory drugs, are the mainstay of treatment for opioid dependency. Constipation, nausea/vomiting, drowsiness/sedation, delirium, itching sensation, voiding difficulty, dry mouth, opioid-induced hyperalgesia, and respiratory depression are well-known physical side effects of opioid consumption. Discussion and Conclusion: Research on the development history, epidemiology of opioid dependency, and its treatment are warranted to avoid an opioid crisis in Korea. Above all, thorough knowledge for physicians and patients is urgently needed.

소프트웨어 라이선스 계약에 대한 민사법 접근 -스트리밍소프트웨어를 중심으로-

고세일 한국경영법률학회 2010 經營法律 Vol.20 No.2

In order to run a computer, software or several programs are necessary. Relatively the software history in technology world is short as computer systems’ is. When we look at this issue in legal perspective, its history becomes much shorter. Network, especially the Internet has changed people's life. Traditionally the concept, “1 pc and 1 program” has been used. However, the development of network has modified the software environment as well. Thus this author deals with software license issues in this Article. In most of cases, legally software is not sold, but just licensed between parties. Accordingly a licensor and a licensee make an agreement concerning their legal relationship of permitting and of using a copy or copies of software. In this respect, a software license is made based on private-autonomy or freedom of contract. Yet, considering how a software license is concluded in a real world, regulations between licensors and licensees are necessary to make their legal relations advisable. Concretely speaking, these are software licensee contract processes, and terms & conditions of licensee contracts. Additionally network development has raised a new question: distribution of a copy of software through network. Thus can a software copyright holder or licensor ask a licensee to stop his or her distribution of a copy or copies of software through network? Regarding this issue, can a software licensee defense using abuse of rights against licensor? These are main issues of this Article. This author explains software and various network technologies in Ⅱ. And then this author deals with principle of private-autonomy or freedom of contract, concerning software licensee agreements in Ⅲ. In addition, this author looks at whether a software copyright holder or licensor can ask a licensee to prevent him or her from distributing a copy or copies of software through network. Also this author examines whether a software licensee can make a defense using abuse of rights against licensor. Finally this author suggests how a software licence would be dealt with in a public policy perspective in Ⅴ.

책임주체로서 지능형 인공지능 로봇에 대한 고찰

고세일 한국재산법학회 2020 재산법연구 Vol.37 No.2

As the word of 4th Industrial Revolution has been widely used to indicate the newest revolution all over the world, it has given the impression that artificial intelligence and robots based on artificial intelligence have been involved in every aspect of all human life. In March 2016, Alphago won all but the fourth Go game over Lee Sedol, professional Go player. The stunning event has put many people’s minds that artificial intelligence has proclaimed that the Google’s Deep Mind had developed intelligent machine’s victory over all humanity. While Artificial intelligence may give us rosy outlook for our future lives, and we also talk a lot about the difficult reality in which the A.I. and A.I. robots would taking people’s jobs sooner or later. At this point, not only the general public, but also lawyers have looked at the areas where the Artificial Intelligence and its A.I. robots may be working with longing and fear at the same time. What would be Artificial Intelligence to us? How should we accept these A.I. and A.I. robots? However, the starting point for these questions may depend on how we view artificial intelligence, and the answer to what social, economic, and legal status could be given to artificial intelligence and artificial intelligence robots. This article consists of five parts. In II., this author has looked at the concepts and status of AI robots. In III., this author has examined the positive and negative legal status discussions of artificial intelligence robots. However, these discussions may vary relying on the levels of technology of artificial intelligence, and its robots. While considering the current technology level, only abstraction discussion may be possible. In this regard, this author has looked at (1) algorithms, (2) autonomous cars, and (3) killer robots as more realistic subjects in IV. And, if there may be a difference between a person and an artificial intelligence robot, the issue that could be considered is (4) different decisions between a person and a A.I. robot with conflict of interests. In V., this author has summarized the discussions so far, and attempted to present a direction on how to consider artificial intelligence robots from today’s point of view. 전 세계에서 4차 산업혁명이라는 단어를 폭발적으로 쓰기 시작하면서, 그 중심에는 인공지능로봇이 인간의 모든 삶에 관여하는 것 같은 인상이 있다. 2016년 3월 이세돌 9단에 대한 알파고의 승리는 많은 사람의 마음속에 인공지능이 모든 인류에 대한 승리를 선포한 인상을 심었다. 인공지능이 앞으로 우리의 미래 삶에 대한 장밋빛 전망을 내놓기도 하고, 인공지능이 많은 사람의 일자리를 빼앗는 현실의 어려움에 대한 이야기를 많이 한다. 어느 순간 일반인뿐만 아니라 법조인들도 인공지능이 자신이 일하는 영역에 대해서 동경과 두려움을 동시에 갖고 바라본다. ‘인공지능’(Artificial Intelligence)은 우리에게 무엇일까? 우리는 이러한 인공지능과 인공지능에 바탕을 둔 로봇을 어떻게 받아들여야 할까? 그런데 이에 대한 출발점은 우리가 인공지능을 어떻게 바라보는지에 따라서, 인공지능과 인공지능 로봇에게 어떤 사회·경제·법의 지위를 줄 수 있는지에 대한 답이 달라진다. 이 글은 모두 다섯 개의 부분으로 이루어진다. II.에서 먼저 인공지능에 바탕을 둔 ‘지능형 인공지능 로봇’의 개념과 현황을 살핀다. III.에서 지능형 인공지능 로봇에 대한 법적 지위를 논하여, 긍정하는 입장과 부정하는 입장을 살펴본다. 그런데 이러한 논의가 지능형 인공지능의 기술 수준에 따라서 달라지는데, 현재의 기술 수준을 고려할 때 추상적인 담론으로 머물 가능성이 있다. 그런 측면에서 IV.에서 좀 더 현실적인 주제로, (1) 알고리즘, (2) 자율주행 자동차, (3) 킬러로봇을 살핀다. 그리고 사람과 지능형 인공지능 로봇 사이의 의사가 다른 경우에, 고려할 수 있는 문제로 (4) ‘의사의 불일치와 이해상반 문제’를 다룬다. V.에서는 지금까지 논의한 내용을 정리하고, 오늘의 시점에서 지능형 인공지능을 어떻게 바라보아야 하는지에 대한 방향성을 제시하고자 한다.

인신손해에 대한 불법행위의 유형과 책임 내용에 대한 연구 - 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정을 중심으로 -

고세일 충남대학교 법학연구소 2019 法學硏究 Vol.30 No.1

The American Restatements are not binding laws. However, there have been many precedents in court cases so that it has not been clear what would be standards of current torts cases in the United States. For this reason, the American Law Institute has attempted to make similar legal codes after making professional groups, such as professors, judges, and lawyers, in each discipline as experts, and for a long time to create important contents in certain specific areas. The most cited Restatements in the US law schools have been the Restatements Second of Contracts. Recently, in tort law more and more legal authors have cited the contents of the Restatements third Torts compared to those of second editions. So far, three third Restatements have been published in the US Tort Law. The first is Product Liability Restatement released in 1998, and the second is Apportionment of Liability Restatement in 2000. The third is Liability for Physical and Emotional Harm published with two volumes in 2010 and 2012. The Liability for Economic Harm and Intentional Torts to Persons are the fourth and fifth Restatements of the Third Edition of the American Law Institute’s Tort Law projects. There are 65 sections in Liability for Physical and Emotional Harm Restatement, whose provisions have described the recent trends and theories of US Tort Law. The provisions of American Liability for Physical and Emotional Harm Restatement have partially replaced those of the second Restatement of Torts. Thus, Liability for Physical and Emotional Harm Restatement have shown recent research achievements of US Tort Law. In this article, this author has examined the contents of Liability for Physical and Emotional Harm Restatement. In II. This author has studed the purposes and dealing areas pursued by Liability for Physical and Emotional Harm Restatement. In III, this author has explained how the provisions have worked, along with specific details of Liability for Physical and Emotional Harm. In IV, this author has finally summarized on what he has discussed so far, and proposed what the implications of the Liability for Physical and Emotional Harm would be for Korean tort law. 미국 보통법전집은 구속력 있는 실정법이 아니다. 그러나 법원 판례로너무나 많은 판례가 쌓여서, 미국 내에 무엇이 판단 기준이 되는 법이 무엇인지 명확하지 않은 경우가 많다. 그런 이유로 미국법률협회(American Law Institute)는 각 분야의 많은 교수, 판사, 변호사를 전문가 집단으로구성하고 오랫동안 일정 영역의 중요한 내용을 법전 형식의 내용으로 만들었다. 미국 법학전문대학원의 교육과정에서 가장 많이 인용되는 보통법전집은 계약법 제2판이고, 최근에는 불법행위 보통법전집 제2판과 견주어 제3판의 내용을 인용하는 추세가 늘어나고 있다. 지금까지 미국 불법행위 보통법전집 제3판으로 세 가지 결과물이 간행되었다. ‘제조물책임’ 보통법전집이 1998년에 처음 나왔고, 두 번째로‘공동불법행위자의 책임분배’ 규정이 나왔다. 세 번째로 ‘재산 손해와 정신적 손해 규정’이 2010년과 2012년에 걸쳐서 두 권으로 간행되었다. 그리고 ‘경제적인 손해에 대한 책임’(Liability for Economic Harm)과 ‘사람에 대한 고의 불법행위’(Intentional Torts to Persons)가 불법행위 보통법전집 제3판의 네 번째와 다섯 번째 결과물로 진행되고 있다. 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정에는모두 65개의 조문이 있다. 미국 불법행위 보통법전집 제3판 재산 손해와정신적 손해 규정은 미국 불법행위 보통법전집 제2판과 달리, 최근 미국불법행위의 이론과 판례 흐름을 좀 더 친절하게 설명한다. 미국 불법행위 보통법전집 제2판은 해당 조문이 어느 판례를 근거로 만들었는지 설명하지 않는다. 그러나 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정은 어느 조문이 어떤 판례를 기초로 만든 규정인지를 명확하게 설명한다. 미국 불법행위 보통법전집 제3판 재산 손해와 정신 손해 규정은 부분적으로 불법행위 보통법전집 제2판을 대체한다. 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정은 인신손해에 대한 미국 불법행위의 최근 연구 성과를 보여준다. 이 글에서는 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정 내용을 살피고자 한다. 먼저II.에서는 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정이 추구하는 목적과 다루는 영역을 살핀다. III.에서는 미국 불법행위보통법전집 제3판 재산 손해와 정신적 손해 규정의 구체적인 내용과 함께 그 규정이 어떻게 기능하는지를 설명한다. IV.에서는 지금까지 논의한 내용을 중심으로 미국 불법행위 보통법전집 제3판 재산 손해와 정신적 손해 규정이 현행 우리 불법행위법에 주는 시사점을 밝힌다.

CD44 Variant 9 Serves as a Poor Prognostic Marker in Early Gastric Cancer, But Not in Advanced Gastric Cancer

고세일,고경혁,이원섭,김록범,이정희,정상호,이영준,홍순찬,하우송 대한암학회 2016 Cancer Research and Treatment Vol.48 No.1

Purpose The present study is to investigate the significance of CD44 variant 9 (CD44v9) expression as a biomarker in primary gastric cancer. Materials and Methods With various gastric tissues, we performed immunohistochemical staining for CD44v9. Results The positive expression rates for CD44v9 in tumor, including adenoma, early gastric cancer (EGC), and advanced gastric cancer (AGC), were higher than those in non-tumor tissues (p=0.003). In addition, the higher expression for CD44v9 was observed as the tissue becomes malignant. In the analysis of 333 gastric cancer tissues, we found that positive expression rates for CD44v9 were higher in the intestinal type or well differentiated gastric cancer than in the diffuse type or poorly differentiated gastric cancer. Interestingly, the positive expression indicated poor prognosis in EGC (5-year survival rate [5-YSR] in stage I, 81.7% vs. 95.2%; p=0.013), but not in AGC (5-YSR in stage II, 66.9% vs. 62.2%; p=0.821; 5-YSR in stage III, 34.5% vs. 32.0%; p=0.929). Moreover, strong positive expression (3+) showed a trend suggesting worse prognosis only in EGC, and it appeared to be associated with lymph node metastasis. Conclusion This study suggests that CD44v9 may be a good biomarker for prognosis prediction and for chemoprevention or biomarker-driven therapies only for EGC.