The introduction of biennial colorectal cancer screening in a region of France increased the rate of diagnosis of high risk pre-cancerous adenomas (sometimes called polyps) by 89%, researchers have reported at the ESMO 2014 Congress in Madrid.  

Dr Vanessa Cottet from INSERM Unité 866 in Dijon, France, and colleagues studied the region of Côte-d’Or, where a registry has been collecting data on adenomas since 1976.

They wanted to evaluate the rate of diagnosis of adenomas before and after the initiation of a screening program using faecal occult blood testing that began in 2003.

The study included all residents aged between 50 and 74 years of age who had a first adenoma identified between January 1997 and December 2008.

The researchers showed that 38.7% of these people had high-risk adenomas – meaning they were larger than 1 centimetre in diameter, involved the finger-like projections called villi in the intestinal lining, or exhibited a high grade of dysplasia.

For such high-risk adenomas, age-standardised diagnosis rates were 136 per 100,000 people before screening program and 257 per 100,000 after, which correlates to a percentage increase of 89%.

The corresponding rates for non-advanced adenomas were 235 and 392 diagnoses per 100,000, with a percentage increase of 68%.

These results reinforce the value of extending organised mass screening programmes for colorectal cancer, the authors say.

“It is very important that public follows recommendations and participates in colorectal cancer screening campaigns,” Cottet says.

“Participation rate is a major issue for the success of such programmes.”

The authors also found that the rate of detection did not continue increasing between the 2005 and 2007 rounds of screening.

However, they suggest that shifting the methodology used in the screening programmes from the more common guaiac test to immunochemical testing will improve results in the future.

“Immunochemical faecal occult blood tests outperform guaiac tests for the detection of colorectal cancer and advanced adenoma,” Cottet says.

“They have doubled the detection rate of invasive colorectal cancer, mostly at early stages, and led to a fourfold increase in the detection rate of non-invasive colorectal cancer and advanced adenomas.”

“Given the superior performance of immunochemical tests, it is reasonable to assume that an organised screening programme using such tests would led to a greater reduction of colorectal cancer death and probably to a reduction in colorectal cancer incidence.”

Commenting on the study, Professor Hans-Joachim Schmoll, former Head of the Division of Haematology and Oncology and Director of the Center for Cell and Gene Therapy, Martin Luther University, Halle, Germany and Professor of Medicine at Martin Luther University, Germany, said that many retrospective and prospective studies have clearly demonstrated the value of screening for adenoma, polyps and manifest colorectal cancer with respect to early diagnosis and treatment of precursor lesions and manifest tumours, and with regard to improving survival.

“However, the question is which method is most appropriate with respect to accessing the target population, maximising participation in these programmes, and efficacy, as well as costs,” Schmoll said.

“The French trial reproduces the positive outcome from other studies by looking on the sequential period before and after 2003 when screening programmes started in the Côte-d’Or region. They have shown that the stool test for occult blood (guaiac test) was effective by doubling the rate and therefore these data further support the value of screening programmes in the general population with a given standard risk, as in this group of people aged 50-75 years.”

“It can definitively be expected that the new FOBT-test could have produced even better results,” Schmoll said.

“Further strong improvement can be expected by the recent new combined test of FOBT together with a molecular test for specific mutations. These third-generation tests are going to be implemented in US and other countries.”

However, the optimal method for increasing the detection rate is colonoscopy, or at least sigmoidoscopy, which is implemented as standard in Germany and in the US, at least for a high risk population, Schmoll said.

These approaches can be called the ‘gold standard’, despite several drawbacks including risks from the procedure itself and potential false positive or negative results, he said.

Source: ESMO