Bowel Check - Peace of Mind

Bowel Cancer – The Size of the Problem

Bowel cancer is a major cause of cancer deaths in New Zealand. On average, someone dies from bowel cancer every 7 hours in New Zealand (1200 per year). Death rates from breast cancer (1 every 14 hours) and road traffic accidents (1 every 20 hours) are lower and yet receive much greater publicity and resources. The lifetime risk of developing colorectal cancer is 1:18 for men, 1:23 for women and 60% of patients will have significant spread to local lymph nodes or metastasis to remote organs at the time of diagnosis or surgery. The ratio of death rates to incidence rates is a measure of the efficacy of case finding and treatment. In New Zealand the ratio is over 50% which compares unfavorably with figures of around 40% achieved in the United States.

What is the risk?

In New Zealand, the lifetime risk of developing bowel cancer is 1 in 18 for men and 1 in 23 for women. In world rankings, New Zealand has the highest rate of bowel cancer in women and the third highest for men. For those who have a family history of bowel cancer, the risk can be as high as 1 in 4.

While family history is a major factor, more bowel cancer actually occurs in individuals without affected relatives, especially those 55 years and older. In fact, the risk increases progressively though 60s, 70s and 80s age groups.

Lifetime risk of developing bowel cancer
*Number of first degree relatives with bowel cancer**	*Age at diagnosis of bowel cancer in youngest first degree relative affected**	Lifetime risk for males	Lifetime risk for females	Recommended age for screening
0		1:18	1:23	50 years
1	>55 years	1:9	1:11	50 years
2	>55 years	1:6	1:8	40 years
1	>45, <55 years	1:6	1:8	40 years
1	<45 years	1:4	1:5	35 years
* First degree = Parent, child, brother or sister.

Bowel Cancer is Preventable

Most cases of bowel cancer are preventable. A number of different strategies for screening for bowel cancer have been suggested and many medical societies and task forces overseas recommend routine screening for colorectal cancer beginning at age 50. Unlike many cancers bowel cancers arise in previously benign polyps which grow over several years before some of the them become cancerous. The objective of screening is to identify these polyps and remove them thus preventing the polyp/cancer sequence.

National Bowel Cancer Screening Programmes

Testing for faecal occult blood (FOB) forms the basis of population screening already underway in many countries. In NZ a pilot programme will start soon but the roll-out nationally will be several years away. FOB testing, while effective for population screening, is not a reliable 'bowelcheck' for an individual as it may miss 50% of cancers and a greater proportion of polyps.

Screening using CT Scanning Colonography

CT Colonography has advantages (it's currently cheaper, no sedation is required and reports suggest fewer complications). However, disadvantages include under-reporting of smaller polyps, the need for follow-on conventional optical colonoscopy in 15-20% and the need for other investigations to follow up other lesions (eg cysts) seen outside the bowel.

Optical Colonoscopy

Optical Colonoscopy is the only screening test with high senstivity (over 95%) and specificity where removal of any polyps occurs at the same time. This means the one procedure provides both investigation and treatment, so while it is more invasive, it is more reliable and further treatment is minimised. Disadvantages relate primarily to cost, the requirement for sedation and higher complication rates usually related to polyp removal procedures.

Of Interest:
The Katie Couric Effect

Katie Couric, co-anchor of the Today Programme on American television produced a series entitled “Confronting Colon Cancer” in the year 2000. She underwent a colonoscopy on camera to increase understanding of this procedure for viewers. As a result of this the number of colonoscopy screenings for bowel cancer has increased almost 20%, a change described as “the Katie Couric Effect”. It is regrettable that no such public awareness campaigns have been initiated in New Zealand and the level of understanding of bowel cancer and its prevention by the public at large is minimal.