05:36pm Wednesday 01 April 2020

Research supports success of non-invasive tests in detection of colorectal cancer

The New England Journal of Medicine published the results from the eight of the Autonomous Communities (the political administrations within the Spanish State) which took part in the research, including the team led by Dr Luis Bujanda from the Digestive System Service at the Hospital Donostia, in the Basque coastal city of Donostia-San Sebastian.

One in twenty 20 persons will contract cancer of the colon or the rectum at some time in their lives. The good news is that it is one of the few cancers that lend itself to early diagnosis, i.e. before the person becomes aware of any symptom. In fact, when thus detected in time, 90% of cases can be cured. The models accepted by the international scientific community for the screening or early detection of colorectal cancer are fundamentally two: faecal occult blood test (European model) and the direct examination of the interior of the colon using colonoscopy (American model). Both are effective for detecting both the cancer itself and its precursor lesions (adenomas, better known as polyps) and, thereby, for preventing the appearance of the cancer and/or improve the reduction in the number of persons diagnosed at an advanced stage of the illness, with the concomitant improvement in survival rates. However, to date the advantages or otherwise of the two methods in the fight against cancer of the colon have never been directly compared, in particular, their acceptation by the population at risk – men and women between the ages of 50 and 69. This is why in 2008 the Spanish Gastroenterology Association (AEG in its Spanish initials) initiated research on a sample population in order to evaluate the impact of both strategies on the death rates in Spain due to this cancer.

The New England Journal of Medicine published the results of this (first time worldwide) comparative study of the two strategies in which public acceptance of both was evaluated as well as the impact of the two methods in the detection of cancerous lesions of the colon and rectum. A total of 60,000 persons from eight Autonomous Communities (Aragon, the Canary Islands, Catalonia, Galicia, Madrid, Murcia, the Basque Country – with a team led by Dr. Luis Bujanda Fernández de Piérola from the Digestive System Service at the Hospital Donostia and lecturer at the University of Basque Country -, and Valencia) participated in the project over a period of four years. The research was co-financed by the Ministry of Economy and Competitiveness, through the Carlos III Health Institute in Madrid, the Spanish Association Against Cancer (aecc), involving the Provincial Governing Bodies in Madrid and Barcelona. The work overall was led by Dr. Antoni Castells, Director of the Institute of Digestive Diseases at the Hospital Clínic in Barcelona and co-ordinator of the Early Detection Programme for Cancer of the Colon and Rectum in Barcelona, and by Dr. Enrique Quintero, Head of the Digestive System Service at the University Hospital of the Canary Islands, in Tenerife.

Using a pragmatic design, in which each participant was randomly adjudicated one of the two early detection tests in order to evaluate which was better accepted and which obtained better performance, the research came to the following conclusion: participation was higher in the faecal occult blood test (34%) than in colonoscopy (25%). Moreover, 1,600 persons requested that the colonoscopy – exploration that has to be effected every 10 years – be employed instead of the faecal occult blood test – a non-invasive test undertaken every two years. Even more important, the number of cancers detected using both methods was identical, most being detected at an initial phase. Finally, the complications observed were minimal in both groups, although inferior in the faecal occult blood test.

“Current methods for the detection of occult blood in faeces are so sensitive that they detect the same cancers that we find with colonoscopy and more than half the precursor lesions (adenomatous polyps) in a single test”, stated Dr. Quintero.

“The final goal of our research is to find out the benefits of both tests for patient survival rates, an effect which we will not be able to know until ten years from now, when the project terminates”, commented Dr. Castells.

Screening or early detection programmes for colorectal cancer: map of Spain

In Spain, colorectal cancer represents the third most common cancer amongst men, after lung cancer and that of the prostate; and the second amongst women, after breast cancer. With about 28,000 new cases a year and taking into account both sexes, cancer of the colon and rectum represents the most frequent type of cancer in our country. Most cases are diagnosed between 65 and 75, with a maximum at 70, although there are cases registered from 35-40. Those cases appearing at early ages usually have a genetic predisposition.

Catalonia, Valencia, Murcia, the Canary Islands, the Basque Country, Cantabria, Extremadura, Castilla León and La Rioja have screening programmes aimed at the target public for the early detection of colorectal cancer. The programmes consist of undertaking a test to detect blood in the faeces not visible to the human eye, as well as individualised attention for persons with increased risk of suffering this cancer because of their family and personal history.

The importance of the early detection of colorectal cancer

The principal object of the screening programmes is to detect colon cancer at an early stage or, even better, prevent its onset and thus reduce the concomitant death rates. If it is detected in time, it is very easy to treat and probabilities of cure are very high. The illness involves a tumour that does not cause any discomfort until the disease is at an advanced stage. Thus, the importance of effecting preventive tests on persons without symptoms. Moreover, it is advisable to have healthy habits such as not to abuse alcohol and tobacco, do exercise and follow a balanced diet.

Early diagnosis amongst women and men between the ages of 50 and 69 without personal or family history of cancer, involves taking a small sample of faeces which is subsequently analysed to see if it contains blood not visible to the naked eye.

Obtaining a negative result from the test indicates that it is highly unlikely that there is cancer of the colon, although this is not 100% guaranteed. This is why it is recommended that the test is repeated every two years and to go to the doctor if symptoms arise. On the other hand, if the result is positive, it is because traces of blood have been found. The presence of blood does not imply, in most cases, that the individual has cancer, but is usually due to a benign lesion, such as polyps. The recommendation in these cases is to carry out an inspection of the inside of the intestine using colonoscopy, undertaken under sedation and the associated risks of which are very low.

For those persons with an increased risk of contracting cancer because of their family and personal history, carrying out a periodic colonoscopy is usually the most suitable strategy, while sometimes it is necessary to carry out genetic analysis in order to more carefully evaluate the risk to the individual and their family members.

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