Establishing a polyp-free colon in the future. Colonoscopy at regular intervals â. Average risk â once per 5 - 10 ye
Screening for Colorectal Cancer Kemal I Deen MS MD FRCS
Kurunegala Clinical Society- 2015
Worldwide West • Colorectal cancer (CRC) is the 2nd most common cancer in women • In men, CRC is the 3rd most common cancer • Overall, CRC is the 4th most common cause of cancer related deaths Sri Lanka 4th most common cancer in 2013 – Globocan
CRC- Potentially totally preventable
• Breast – Screening is aimed at detecting the early cancer • CRC – Screening is aimed at detecting the polyp
Breast vs. Colorectal
Totally preventable?
Almost all CRC develops from a pre-existing, slow growing polyp (adenoma) that is the pre-malignant state of CRC.
The origin of an adenoma Shed off by programmed cell death
Life span of 3 to 5 days
Survives on the epithelial surface using fatty acids derived from luminal bacterial action of fibre
Regulate upward movement of colonocyte
Intestinal stem cells
The origin of an adenoma
The origin of an adenoma
Adenoma to dysplasia to carcinoma Polyp – Dysplasia - Cancer 5 Years
APC Chr 5
K ras Chr 12
DCC Chr 18
p 53 Chr 17
What’s the evidence for screening? • Colonoscopic polypectomy and long-term prevention of colorectalcancer deaths. • Zauber AG1, Winawer SJ, O'Brien MJ, Lansdorp-Vogelaar I, van Ballegooijen M, Hankey BF, Shi W, Bond JH, Schapiro M, Panish JF, Stewart ET, Waye JD. NEJM -2012
53% Reduction in mortality
Effect on CRC incidence in a screened population SEER 9 Incidence & U.S. Mortality 1975-2012, All Races, Both Sexes. Rates are Age-Adjusted.
Year
1975
1980
1985
1990
1995
1999
2003
2007
5-Year Relative Survival
48.6 %
51.1 %
58.0 %
60.8 %
59.7 %
64.5 %
65.3 %
66.5 %
The Aim
Classification of Colorectal Cancer
CRC SPORADIC CANCER
FAMILIAL CANCER
Middle aged / Elderly
Familial Adenomatous Polyposis
Young age 1cm Villous adenoma
• Average risk
Any person >50 (White Caucasian) or >40 South Asian
Principles 1. To establish a colon free of polyps – “Clean Colon” in individuals who reach the “at-risk” age
White Caucasian – 50 years Sri Lankan- 40 Years Familial Adenomatous Polyposis – 12 years Hereditary non-polyposis cancer – 5years before the youngest family member 2. To ensure a colon free of polyps or a colon with an endoscopically treatable polyp during the remainder of an individual’s lifespan
How do we achieve? Establishment of a “clean colon” Total colonoscopy CT- Colonography Flexible sigmoidoscopy + Faecal occult blood tests
Establishing a polyp-free colon in the future Colonoscopy at regular intervals – Average risk – Moderate risk – High risk -
once per 5 - 10 years once per 2 to 5 years once per 3months to 2years
Establishing a polyp-free colon in the future Alternative Faecal occult blood x 3 consecutive days – every 2 years, with flexible sigmoidoscopy every 3 to 5 years
Colonoscopy if faecal occult blood test is positive
When to stop?
Between age 75 to 79 years > 80 – Screening should be considered on an individual basis
Conclusion Colonoscopic screening is recommended in all current guidelines at 10-year intervals in the average-risk population at 5 to 10-year intervals among patients with 1 or 2 small (3 small adenomas, an adenoma with villous features or highgrade dysplasia, or an adenoma>1 cm in size. Systematic overuse of colonoscopy for screening and polyp surveillance must be avoided – it is not cost effective and it exposes patients to excess risk, and its systematic performance cannot be justified.
