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Strategies for detecting colon cancer and/or dysplasia in patients with inflammatory bowel disease

  • Review
  • Intervention




Patients with longstanding ulcerative colitis and colonic Crohn's disease have an increased risk of colorectal cancer compared with the general population. This review assesses the evidence that endoscopic surveillance may prolong life by allowing earlier detection of colon cancer or its pre-cursor lesion, dysplasia, in patients with inflammatory bowel disease.


To assess the effectiveness of cancer surveillance programs in reducing the death rate from colorectal cancer in patients with ulcerative colitis and colonic Crohn's disease.

Search methods

The following strategies were used to identify relevant studies:
1. MEDLINE and the Cochrane Central Register of Controlled Trials were searched from 1966 to August 2005. The medical subject headings "Ulcerative Colitis", "Crohn Disease" or "Inflammatory Bowel Disease" and "Surveillance" or "Cancer" were used to perform key-word searches of the databases.
2. Hand searching of reference lists from papers.

Selection criteria

Potentially relevant articles were reviewed independently and unblinded by three authors to determine if they fulfilled the selection criteria. Each article was rated as being eligible, ineligible, or without sufficient information to determine eligibility. Any disagreement between reviewers was resolved by consensus. Any trials published in abstract form were only considered if it was possible to obtain full details of the protocol and results from the authors.

Data collection and analysis

Eligible articles were reviewed in duplicate and the results of the primary research trials were abstracted onto specially designed data extraction forms. The proportion of patients dying from bowel cancer or other causes in the control and surveillance groups of each study was derived from life tables, survival curves or where possible, by calculating life tables from the data provided. Data from the original research articles were converted into 2x2 tables (survival versus death x surveillance versus control) for each of the individual studies for comparable follow-up intervals. The presence of significant heterogeneity among studies was tested by the chi-square test. Because this is a relatively insensitive test, a P value of less than 0.1 was considered statistically significant. Provided statistical heterogeneity was not present, the fixed effects model was used for the pooling of data. The 2x2 tables were combined into a summary test statistic using the pooled relative risk (RR) and 95% confidence intervals as described by Cochrane and Mantel and Haenszel.

Main results

Karlen 1998a in a nested case-control study comprising 142 patients from a study population of 4664 UC patients, found that 2/40 patients dying of colorectal cancer had undergone surveillance colonoscopy on at least one occasion compared with 18/102 controls (RR 0.28, 95% CI 0.07 to 1.17). One of 40 patients who died from colorectal cancer had undergone surveillance colonoscopies on two or more occasions compared with 12/102 controls (RR 0.22, 95% CI 0.03 to 1.74) in contrast to a more modest effect observed for patients who had only one colonoscopy (RR 0.43, 95% CI 0.05 to 3.76). Choi 1993 found that carcinoma was detected at a significantly earlier stage in the surveilled patients; 15/19 had Duke's A or B carcinoma in the surveilled group compared to 9/22 in the non-surveilled group (P = 0.039). The 5-year survival rate was 77.2% for cancers occurring in the surveillance group and 36.3% for the no-surveillance group (P = 0.026). Four of 19 patients in the surveillance group died from colorectal cancer compared to 11 of 22 patients in the non-surveillance group (RR 0.42, 95% CI 0.16 to 1.11). Lashner 1990 found that four of 91 patients in a surveillance group died from colorectal cancer compared to 2 of 95 patients in a non-surveilled group (RR 2.09, 95% CI 0.39 to 11.12). Colectomy was less common in the surveillance group, 33 compared to 51 (P < 0.05) and was performed four years later (after 10 years of disease) in the surveillance group. For the pooled data analysis 8/110 patients in the surveillance group died from colorectal cancer compared to 13/117 patients in the non-surveillance group (RR 0.81, 95% CI 0.17 to 3.83).

Authors' conclusions

There is no clear evidence that surveillance colonoscopy prolongs survival in patients with extensive colitis. There is evidence that cancers tend to be detected at an earlier stage in patients who are undergoing surveillance, and these patients have a correspondingly better prognosis, but lead-time bias could contribute substantially to this apparent benefit. There is indirect evidence that surveillance is likely to be effective at reducing the risk of death from IBD-associated colorectal cancer and indirect evidence that it may be acceptably cost-effective.








関連性のある研究を同定するため、以下の検索戦略を用いた。1.1966年から2005年8月までのMEDLINEおよびCochrane Central Register of Controlled Trialsを検索した。医学用語のサブジェクト・ヘディングとして「Ulcerative Colitis(潰瘍性大腸炎)」、「Crohn Disease(クローン病)」または「Inflammatory Bowel Disease(炎症性腸疾患)」および「Surveillance(監視)」または「Cancer(癌)」を、データベースのキーワード検索に使用した。2.論文の参照文献リストのハンドサーチ。


3名のレビューアが独自に非盲検で関連論文をレビューし、選択基準を満たすかどうかを判定した。各論文は、適格である、適格でない、または適格性を判定するための十分な情報がないに分類した。 レビューア間の不一致はすべて合意によって解消した。要約の形で発表された試験は、著者から完全で詳細なプロトコールと結果が入手できた場合にのみ、検討を行った。


適格な論文は二重にレビューし、主要な研究試験の結果を特別にデザインしたデータ抽出書式に要約した。各研究のコントロール群および監視群における大腸癌または他の原因で死亡した患者の割合は、生命表、生存曲線から、または可能な場合は提示されたデータから生命表を計算することによって導き出した。個別の研究ごとに同等の追跡期間について、原著論文からのデータを2×2の表に変換した(生存と死亡との比較×監視とコントロールとの比較)。 研究間に有意な異質性が存在するかどうかについて、X2検定を用いて調べた。これは比較的感度の低い検定であることから、P値が0.1未満の場合に統計学的に有意であるとした。統計学的な異質性がない場合は、プールしたデータに対して固定効果モデルを用いて評価した。2×2の表をCochrane-Mantel-Haenszel法で統合して要約統計量とし、相対リスク(RR)とその95%信頼区間で示した。


潰瘍性大腸炎患者4664例から成る研究集団中の患者142例で構成されたコホート内の症例対照研究においてKarlen 1998aは、大腸癌のために死亡した患者40例中2例は少なくとも1回結腸内視鏡検査による監視を受けていたのに対し、対照群では102例中18例であった(RR 0.28、95% CI 0.07~1.17)ことを見出した。大腸癌のために死亡した患者40例中1例が2回以上結腸内視鏡検査による監視を受けていたのに対し、対照群では102例中12例であり(RR 0.22、95% CI 0.03~1.74)、反対に1回しか結腸内視鏡検査を受けていなかった患者では軽度の効果が認められた(RR 0.43、95% CI 0.05~3.76)。Choi1993は、監視を行った患者では有意に早期の癌が発見されたことを見出した。すなわち、監視群の19例中15例はデュークス分類のAまたはBの癌であったのに対し、非監視群では22例中9例であった(P=0.039)。5年生存率は監視群で発生した癌では77.2%であったのに対し、非監視群では36.3%であった(P=0.026)。監視群の患者19例中4例が大腸癌のために死亡していたのに対し、非監視群では22例中11例であった(RR 0.42、95% CI 0.16~1.11)。Lashner 1990は、監視群患者の91例中4例が大腸癌のために死亡したのに対し、非監視群では95例中2例であったことを見出した(RR 2.09、95% CI 0.39~11.12)。結腸切除術は監視群の方が少なく、33例対51例であり(P<0.05)、監視群の方が4年遅く(罹患から10年後)施行された。統合データの解析では、監視群患者110例中8例が大腸癌のために死亡したのに対し、非監視群では117例中13例であった(RR 0.81、95% CI 0.17~3.83)。




監  訳: 柴田 実,2007.10.5

実施組織: 厚生労働省委託事業によりMindsが実施した。

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Plain language summary

Strategies for detecting colon cancer and/or dysplasia in patients with inflammatory bowel disease

Patients with long-standing ulcerative colitis and colonic Crohn's disease have an increased risk of colorectal cancer compared with the general population. This review shows that there is no conclusive evidence that surveillance colonoscopy prolongs survival in these patients. However, since the principal studies were completed it has become clear that numerous biopsies are needed to accurately identify pre-cancerous lesions (dysplasia) and that the benefit of surveillance could have been greater if multiple biopsies had been performed. It has also since been demonstrated that targeted biopsy of dysplastic areas is enhanced by dye spraying at colonoscopy. There is evidence from case control studies that cancers tend to be detected at an earlier stage in patients who are undergoing surveillance and that these patients have a better chance for recovery. This evidence should be treated with caution since lead-time bias (the period between early detection of disease and the time of its usual clinical presentation) may contribute substantially to this apparent benefit. It is unlikely that there will be a randomised trial of surveillance colonoscopy in patients with colitis. Lower quality evidence, however, supports the continued use of some form of surveillance for these patients. The nature of this surveillance is gradually evolving, with two important developments since the last version of this review in 2004. Firstly, it has become apparent that most pre-malignant (dysplastic) lesions can be visualised with careful endoscopy. Secondly, patients who lack histological inflammation on colonoscopy are at low risk for cancer development.

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