Screening for colorectal cancer using the faecal occult blood test, Hemoccult

 

Abstract

Background

Colorectal cancer is a leading cause of morbidity and mortality, especially in the Western world. The human and financial costs have prompted considerable research to evaluate screening tests to detect the cancer at an early curable stage. Tests that have been considered for population screening include the faecal occult blood test (FOBT), flexible sigmoidoscopy and colonoscopy. Reducing mortality from colorectal cancer (CRC) may be achieved by the introduction of population-based screening programmes.

Objectives

To determine whether screening for colorectal cancer using the faecal occult blood test (guaiac or immunochemical) reduces colorectal cancer mortality and to consider the benefits and harms of screening.

Search methods

Published and unpublished data for this review were identified by:

Reviewing studies included in the previous Cochrane review;
Searching several electronic databases (Cochrane Library, Medline, Embase, CINAHL, PsychInfo, Amed, SIGLE, HMIC); and
Writing to the principal investigators of potentially eligible trials.

Selection criteria

We included all randomised trials of screening for colorectal cancer that compared faecal occult blood test (guaiac or immunochemical) on more than one occasion with no screening and reported colorectal cancer mortality.

Data collection and analysis

Data from the eligible trials were independently extracted by two reviewers. The primary data analysis was performed using the group participants were originally randomised to ('intention to screen'), whether or not they attended screening; a secondary analysis adjusted for non-attendance. We calculated the relative risks and risk differences for each trial, and then overall, using fixed and random effects models (including testing for heterogeneity of effects). We identified nine articles concerning four randomised controlled trials and two controlled trials involving over 320,000 participants with follow-up ranging from 8 to 18 years.

Main results

Combined results from the 4 eligible randomised controlled trials shows that participants allocated to FOBT screening had a statistically significant 16% reduction in the relative risk of colorectal cancer mortality (RR 0.84; CI: 0.78-0.90). In the 3 studies that used biennial screening (Funen, Minnesota, Nottingham) there was a 15% relative risk reduction (RR 0.85, CI: 0.78-0.92) in colorectal cancer mortality. When adjusted for mean screening attendance in the individual studies, there was a 25% relative risk reduction (RR 0.75, CI: 0.66 - 0.84) for those attending at least one round of screening using the faecal occult blood test.

Authors' conclusions

Benefits of screening include a modest reduction in colorectal cancer mortality, a possible reduction in cancer incidence through the detection and removal of colorectal adenomas, and potentially, the less invasive surgery that earlier treatment of colorectal cancers may involve.
Harmful effects of screening include the psycho-social consequences of receiving a false-positive result, the potentially significant complications of colonoscopy or a false-negative result, the possibility of overdiagnosis (leading to unnecessary investigations or treatment) and the complications associated with treatment.

 

Plain language summary

Screening for colorectal cancer using the faecal occult blood test, Hemoccult

Regular screening of faeces for blood can detect colorectal cancer earlier and hence may reduce mortality in populations at risk, such as older patients. The screening test used in these trials to detect colorectal (bowel) cancer was the faecal occult blood test (FOBT). If the FOBT is positive, the bowels are examined closely with further diagnostic test (coloscopy, flexible sigmoidoscopy, double-contrast barium enema), but these tests often cause discomfort and can cause serious adverse consequences. As blood identified in faeces may be due to several reason (unrelated to cancer), it may cause people unnecessary stress and expose them to possible harm. This review found that FOBT screening is likely to avoid approximately 1 in 6 colorectal cancer deaths.

 

摘要

背景

使用糞便潛血檢驗來做大腸直腸癌篩檢

大腸直腸癌是常見的致病和致死病因,特別是在西方國家。由於這個疾病的人類和經濟效益促成大量的研究去希望在早期篩檢發現大腸直腸癌.用來篩檢的方法包括有:糞便潛血檢驗(faecal occult blood test),軟式乙狀結腸鏡和大腸鏡.可由集體篩檢的引入來達成大腸直腸癌(CRC)死亡率的下降

目標

要決定是否可用糞便潛血試驗(guaiac或免疫法)來篩查大腸直腸癌並降低大腸直腸癌死亡率，並考慮利益，危害和可能產生的後果

搜尋策略

這次審查發表和未發表的數據，確定了: 審查研究，包括在以前的Cochrane醫學審查 搜索幾個電子資料庫(Cochrane Library, Medline, Embase, CINAHL ， PsychInfo ， Amed ，單， HMIC) ;和 寫給合適試驗的主要調查員

選擇標準

我們在這次審查包括所有隨機試驗的大腸直腸癌篩查，對照不止一次糞便潛血試驗(guaiac或免疫)，和沒有篩檢的大腸直腸癌死亡率

資料收集與分析

這次審查由兩位審員獨立提取所有隨機試驗篩選數據。主要數據的分析，使用組參與者隨機原先以(‘打算篩選’) ，不管他們是否參加篩查;一個次要的分析調整後的非attendence 。我們計算的相對風險和風險的差異每個審判，然後整體而言，使用固定和隨機效應模型(包括測試的非均質性的影響) 。我們檢視了9個論文涉及四個隨機對照試驗和兩個對照試驗涉及32.0萬參與者和追蹤8至18年

主要結論

4個隨機對照試驗的聯合結果顯示，參與者分配到給篩檢者減少了16 ％的大腸直腸癌死亡率相對危險性(RR 0.84, CI: 0.78 – 0.90)。在3個研究，用兩年篩查(Funen, Minnesota, Nottingham)有15 ％的相對危險度減少率(RR 0.85, CI: 0.78 – 0.92)在大腸直腸癌的死亡率。當調整篩選出席在個別的研究，當參加者至少利用一次糞便潛血試驗篩檢則有25 ％的相對危險度減少率(RR 0.75, CI: 0.66 – 0.84)

作者結論

篩選的好處包括：適度減少大腸直腸癌死亡率，減少大腸直腸癌發病率經由檢測和清除大腸腺瘤，早期治療大腸直腸癌使用微創手術。篩查的有害影響包括收到了假陽性結果後的心理和社會後果，結腸鏡檢查或假陰性結果的潛在重大併發症，可能過度診斷(導致不必要的檢查或治療)和治療後併發症

翻譯人

本摘要由國泰綜合醫院張世昌翻譯

此翻譯計畫由臺灣國家衛生研究院(National Health Research Institutes, Taiwan)統籌

總結

定期檢查糞便血液可以早期檢測大腸直腸癌，因此可能會降低高危險群的死亡率，諸如老年患者。篩選試驗中使用的這些試驗檢測大腸直腸(腸)癌症是糞便潛血試驗(FOBT)。如果在糞便潛血試驗是陽性的，腸道便須進一步密切檢查與診斷(coloscopy, flexible sigmoidoscopy, doublecontrast barium enema), 但這些檢查往往造成不適，和可能會造成嚴重的不良後果。隨著糞便的血液檢出可能是由於某些原因(無關的癌症)，它有可能造成人們不必要的壓力和造成他們可能的損害。本次審查發現糞便潛血試驗篩選，可以避免可能約為1比6大腸直腸癌死亡