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 <40

Hereditary non-polyposis CRC One 1st degree relative with CRC

Colorectal Cancer Risk • High risk

FAP family members; Longstanding ulcerative colitis Crohn’s Colitis; HNPCC.

• Moderate risk

Previous CRC; >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 (<10 mm) tubular adenomas, at 5-year intervals when there is a history of advanced adenomas on previous colonoscopies, and at 3-year-intervals for patients with>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.