Colorectal Cancer Screening

New Zealand has the highest documented rate per capita of colorectal cancer in the World. Colorectal (bowel) cancer is the most common cancer in New Zealand (excluding superficial skin cancers). Each year approximately 2,000 New Zealanders are diagnosed with colorectal cancer and 1,000 die from the disease. One out of every 15 New Zealanders will develop colorectal cancer sometime in their lifetime. The risk for people who have one close relative with colorectal cancer increases by a factor of 1.7 and with two or more first-degree relatives by a factor of 2.75.

Already national screening programmes exist for breast cancer where the lifetime risk for a New Zealand woman is approximately 1 in 12.

Similarly, a national cervical cancer screening programme is in place for cervical cancer where a lifetime risk factor is approximately 1 in 200. Already screening programmes to detect early malignant and pre-malignant colorectal growths are in place in America, Australia and the United Kingdom and statistical evidence as to the long term benefits with respect to decreasing mortality as a result of these programmes is emerging. Intus recommendations for colorectal cancer screening are formulated from the general guidelines as recommended by the Australian Gastroenterology Institute and the American Gastroenterological Association and are supported by extensive supporting literature. Copies of the individual papers can be supplied on request.

The following general guidelines serve as the background against which these recommendations should be applied:

• People with symptoms that suggest the presence of colorectal cancer or polyps* should have appropriate diagnostic evaluation. They are not candidates for screening.
• Personal and familial risk factors need to be evaluated when considering screening.
• Screening for colorectal cancer and pre cancerous polyps should be offered to all men and women beginning at age 50.
• Physicians should recommend a full diagnostic evaluation of the colon to follow up positive screening test.
• Follow up surveillance should be considered after treatment of colorectal cancer or removal of adenomatous polyps or in the presence of underlying pre-malignant conditions such as inflammatory bowel disease. Healthcare providers who perform the tests should have appropriate proficiency and the tests should be performed correctly.
• Screening should be accompanied by efforts to optimise a participation of patients and healthcare providers both with screening tests and appropriate diagnostic follow up.
• People who are candidates for screening should be given adequate information on the risks and benefits of the various screening procedures.

* A polyp is a mass or lump on the wall of the colon. It is an overgrowth of glandular cells in the lining of the colon. Adenomatous polyps have the potential to turn cancerous. It takes a period of years for a polyp to turn into a cancer.

The cause of polyps is unknown. If your family members have had polyps or colorectal cancer your risk of developing the disease is higher. Also, if you have had a polyp or cancer in the past, you are more at risk of developing future polyps or cancer. When a polyp is found it should be removed and examined by a Pathologist. When one polyp is found there is a 40% chance there will be others present in the bowel so it is important to examine the entire colon.

Relevant Links

Endoscopy
Capsule Endoscopy
Intus
Colonoscopy