12:29am Thursday 16 July 2020

RCSI Researchers find bowel cancer screening process can detect one third more cancers

This new study by led by Dr David Hughes, Department of Physiology and Medical Physics, RCSI, was recently published in the online journal Colorectal Disease. The research involved using a new two-part screening test called an Immunochemical Faecal Occult Blood Test or FOBT (FIT) instead of the original Faecal Occult Blood Test (FOBT) which is a widely used screening tool for colorectal cancer used to detect blood in a person’s stool.

The FIT test, when used twice over consecutive days, is used to indicate the presence of both pre-cancerous growths and cancers in the colon by detecting a minute sample of blood in the stool at a cut off of 100 nanograms of blood per millilitre of stool (100 ng/ml). When compared to a one-test FIT, researchers found that the duplicate FIT screening test detects presence of up to one third (27.5%) more significant colorectal neoplasis (advanced colorectal growths and cancers).These precancerous growths can advance to cancerous stages if they are not detected early. Just one of the two FIT tests needs to be positive for the patient to be referred for a colonoscopy.

They also discovered that a cut-off threshold of 100ng/ml is suitable to optimise colorectal cancer screening in Ireland and any lower cut-off would increase the required colonoscopy numbers to a rate that would over-burden capacity in the Irish health system.

The two-test protocol had a positivity rate of 10.2%, which means that approximately one in ten people tested positive for cancer. One third had screen relevant growths in the colon and the remainder had minor issues such as haemorrhoids or else had no abnormalities.

Principal Investigator of this study, Dr David Hughes said, ‘The miss rate estimated for a single test (FOBT) of nearly 30% is unacceptably high when the goal is to maximize the discovery of advanced lesions in an initial population screening round. The FIT test is vital for the detection of pre-cancerous growths in the colon and is cost-effective. However, the rates from this study have found that additional colonoscopy services will be required for a national screening programme’

The Adelaide and Meath hospital, incorporating the National Children’s hospital/ Trinity College Dublin Colorectal Cancer Screening Programme (TTC-CRC-SP) has used the two sample FIT protocol for colorectal cancer screening on residents aged between 50-75 years within the AMNCH hospital catchment area of Dublin 24 since 2008.

Royal College of Surgeons in Ireland, 123 St Stephens Green, Dublin 2, Ireland.  Tel: +353 1 402 2100

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