**3.2 Flexible sigmoidoscopy (FS)**

FS needs less rigorous bowel preparation and can be performed as a clinic-based procedure without the need for sedation. Small polyps can be biopsied during procedure but excision of larger lesions (>1 cm) may be performed during subsequent colonoscopy.

In two randomized controlled trial studies conducted in the United States and the United Kingdom, sigmoidoscopy reduces the CRC incidence by 18-26% and mortality by 26-30% in general population. The reduction in mortality, however, was limited to distal colon, with no significant effect in the proximal colon [11, 12].

## **3.3 Colonoscopy**

Colonoscopy is the screening modality that has the ability to visualize the colonic mucosa directly, perform biopsy and excise polyps. It can detect proximal lesions that would be missed by screening sigmoidoscopy and has been shown to reduce risk of cancer in the right colon, while for those who has had colonoscopy especially for screening, the risk of CRC is strongly reduced by 91% up to 10 years [13]. In different study, it was also found that screening colonoscopy was associated with a substantial and comparably decreased mortality risk for both right-sided (65% reduction) and left-sided (75% reduction) cancers within a large community-based population [14].

According to the American College of Gastroenterology Guidelines, the preferred CRC prevention test (screening test) with strong recommendation is colonoscopy every 10 years, beginning at age of 50 based on the evidence of effectiveness, cost-effectiveness and acceptance by patients [15]. The National Cancer Comprehensive Network Clinical Practice Guidelines for Colorectal Cancer Screening also stated that colonoscopy is currently the preferred screening method. It is also the required procedure for confirmation of positive findings from other screening tests [16].

However, based on the updated Asia Pacific Consensus on Colorectal Cancer report in 2013, colonoscopy is recommended for those with an increased risk of CRC based upon the family history of CRC and other related risk factors for CRC. This recommendation has been suggested by the panel in view of colonoscopy being an invasive, labour intensive and more expensive method for CRC screening [17].

### **3.4 Colon capsule endoscopy (CCE)**

CCE is used to obtain images of the colon by using video cameras embedded in an ingested capsule. The technique is less invasive but does not allow biopsy or polyp removal.

The sensitivity in detection of polyps >6 mm and > 10 mm increased substantially between development of first-generation (CCE-1) and second-generation (CCE-2) of CCE. CCE-2 and CCE-1 detect polyps >6 mm with sensitivity of 86% (95% CI 82–89%) and 58% (95% CI 44–70%) respectively, and specificity of 88.1% (95% CI 74.2%–95.0%) and 85.7% (95% CI 80.2%–90.0%) respectively. While for larger polyps >10 mm, CCE-2 and CCE-1 had sensitivity of 87% (95% CI 81–91%) and 54% (95% CI 29–77%) respectively, and specificity of 95.3% (95% CI, 91.5%– 97.5%) and 97.4% (95% CI 96.0%–98.3%) respectively [18]. These high specificity

test has a higher sensitivity at 92% (95% CI 84 to 97) to detect CRC [5]. These two fecal tests for CRC screening are, however, not widely used locally in screening for

FS needs less rigorous bowel preparation and can be performed as a clinic-based

In two randomized controlled trial studies conducted in the United States and the United Kingdom, sigmoidoscopy reduces the CRC incidence by 18-26% and mortality by 26-30% in general population. The reduction in mortality, however, was limited to distal colon, with no significant effect in the proximal colon [11, 12].

Colonoscopy is the screening modality that has the ability to visualize the colonic mucosa directly, perform biopsy and excise polyps. It can detect proximal lesions that would be missed by screening sigmoidoscopy and has been shown to reduce risk of cancer in the right colon, while for those who has had colonoscopy especially for screening, the risk of CRC is strongly reduced by 91% up to 10 years [13]. In different study, it was also found that screening colonoscopy was associated with a substantial and comparably decreased mortality risk for both right-sided (65% reduction) and left-sided (75% reduction) cancers within a large community-based

According to the American College of Gastroenterology Guidelines, the preferred CRC prevention test (screening test) with strong recommendation is colo-

However, based on the updated Asia Pacific Consensus on Colorectal Cancer report in 2013, colonoscopy is recommended for those with an increased risk of CRC based upon the family history of CRC and other related risk factors for CRC. This recommendation has been suggested by the panel in view of colonoscopy being an invasive, labour intensive and more expensive method for CRC screening [17].

CCE is used to obtain images of the colon by using video cameras embedded in an ingested capsule. The technique is less invasive but does not allow biopsy or

The sensitivity in detection of polyps >6 mm and > 10 mm increased substantially between development of first-generation (CCE-1) and second-generation (CCE-2) of CCE. CCE-2 and CCE-1 detect polyps >6 mm with sensitivity of 86% (95% CI 82–89%) and 58% (95% CI 44–70%) respectively, and specificity of 88.1% (95% CI 74.2%–95.0%) and 85.7% (95% CI 80.2%–90.0%) respectively. While for larger polyps >10 mm, CCE-2 and CCE-1 had sensitivity of 87% (95% CI 81–91%) and 54% (95% CI 29–77%) respectively, and specificity of 95.3% (95% CI, 91.5%– 97.5%) and 97.4% (95% CI 96.0%–98.3%) respectively [18]. These high specificity

noscopy every 10 years, beginning at age of 50 based on the evidence of effectiveness, cost-effectiveness and acceptance by patients [15]. The National Cancer Comprehensive Network Clinical Practice Guidelines for Colorectal Cancer Screening also stated that colonoscopy is currently the preferred screening method. It is also the required procedure for confirmation of positive findings from other

procedure without the need for sedation. Small polyps can be biopsied during procedure but excision of larger lesions (>1 cm) may be performed during subse-

general population due to high cost incurred.

**3.2 Flexible sigmoidoscopy (FS)**

quent colonoscopy.

*Colorectal Cancer*

**3.3 Colonoscopy**

population [14].

screening tests [16].

polyp removal.

**6**

**3.4 Colon capsule endoscopy (CCE)**

values for detection of polyps by CCE seem to be achievable with a 10-mm cutoff and in a screening setting.
