The National Health Service Bowel Cancer Screening Program: the early years

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Date: July 2013
Publisher: Expert Reviews Ltd.
Document Type: Report
Length: 10,301 words
Lexile Measure: 1410L

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Author(s): Colin J Rees [*] 4 2 3 , Roisin Bevan 1 2

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colonoscopy quality; colorectal cancer; population-based screening

Bowel cancer

Colorectal cancer (CRC) is the third most frequent cancer in the UK, and the second commonest cause of cancer deaths, with approximately 13,000 deaths per year in the UK [101] .

The unadjusted lifetime CRC risk is 1 in 19 for women and 1 in 14 for men. An increased risk is present in conditions such as familial adenomatous polyposis (FAP), Crohn's colitis, ulcerative colitis and hereditary non-polyposis colorectal cancer (HNPCC)/Lynch syndrome and these groups are targeted for screening [1] . Risk is increased in those with a family history of CRC. Currently in the UK, those with more than one first degree relative affected by CRC, or one first degree relative affected with CRC under 60 years of age are offered a one-off colonoscopy at 55 years of age [1] . However, 90% of CRC are sporadic. In the general population, the greatest risk factor for developing CRC is age, with 73% of bowel cancers diagnosed over the age of 65 [102] .

CRC develops as a consequence of the adenoma-carcinoma sequence [2] . Vogelstein's hypothesis states there is a progression, via a series of cellular mutations, from normal mucosa, to adenomas with mild dysplasia, then to adenomas with severe dysplasia, and ultimately to CRC (Figure 1). This process occurs over 10-15 years, and the period from development of cancer to presentation with symptoms may be over many years.

By the time a CRC becomes symptomatic it is often already at an advanced stage i.e., Dukes' stage C (spread to regional or distance lymph nodes) or D (distance metastase) [3] , and 5-year survival decreases with worsening stage (Table 1) [4] . Treatment options change with stage of disease, there being more curative potential with earlier stage disease.

Screening: possible modalities

Screening for high-risk groups is well established but the UK wished to develop a population-based screening program for CRC as had previously been initiated for breast and cervical cancers. Possible methods were reviewed with regards to the principles of screening [5] , with several different methods considered. Much work has been done on the use of fecal occult blood testing (FOBt) as an initial screening method [6-10] , and a systematic review [11] concluded that there was sufficient evidence that screening some population groups with FOBt would be beneficial.

Flexible sigmoidoscopy (FS) as a screening tool without prior stratification with FOBt has been shown to reduce mortality from cancers in the rectum and sigmoid colon, and the frequency of testing can be as low as every 6-10 years [12-15] . However, at the time of the Department of Health making a decision about screening, this method was not viable within the constrains of endoscopy services in the UK despite being more cost-effective than an FOBt screening method [16] .

CT scanning to provide virtual colonoscopy has been shown to compare favorably with optical colonoscopy in the detection of clinically relevant lesions [17] , and when fecal tagging is used, bowel cleansing...

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Gale Document Number: GALE|A339495926