Saturday, 8th August 2020

This Month's Magazine


Colorectal cancer is one of the most common malignancies and one of the main causes of death from cancer. - by José Miguel Rosales Zábal - Gastroenterology Unit

Survival is much improved when diagnosed early, hence the importance of screening tests to enable a diagnosis as early as possible.

The incidence of this type of cancer increases with age, with the majority of cases occurring in those over the age of 50. For this reason, the majority of professional  bodies and guidelines recommend starting screening tests at the age of 50, bearing in mind that each person’s case must be assessed individually to more accurately  estimate that person’s risk. Tests performed on samples of faeces are amongst the most straight-forward due to their ease and affordability, they are basically of three  types: those which detect occult blood in stools, and “multitarget” tests which also detect genetic mutations associated with this type of cancer. Below we explain these  tests in more detail.

There are two main types:

  1. Immunohistochemical test: directly measures the haemoglobin (a blood component) in faeces. Only a small sample of faeces is required, this must be taken to  the laboratory within 24 hours so that the sensitivity of the test is not diminished. Testing once a year, the sensitivity for detecting colorectal cancer is almost  74% and the sensitivity for detecting polyps of 10 mm or more is 24%. For smaller polyps measuring 6 to 9 mm or less than 5 mm, sensitivity is lower, at little  more than 7%.
  2. The guaiac test: detects the presence of haemoglobin by changing the colour of paper impregnated with a reagent (alpha-guaiaconic acid).  When performed yearly it shows a sensitivity for detecting colorectal cancer of 70%, a sensitivity for detecting polyps, of at least 10 mm, of 24%, a sensitivity for  etecting polyps of 6 to 9 mm of 12.4% and a sensitivity for polyps of less than 5 mm of 7.5%.
  3. Multitarget stool DNA test. This test combines the detection of haemoglobin using immunohistochemical techniques, with the detection of genetic mutations  associated with colorectal cancer in the remains of DNA eliminated in the faeces. Their sensitivity when performed yearly is of 92.3% for the detection of colorectal cancer, 42.4% for the detection of polyps of at least 10 mm and 17.2% for polyps of 6 to 9 mm or less than 5 mm.



The following table summarises these tests:A positive result from any of these tests, requires more specific testing, in other words colonoscopy. This facilitates the detection of the cause of the positive result, as  in many cases it will not be due to a malignant tumour. It also enables the removal of small lesions such as polyps.

The study of each person’s individual case is still  recommended to ascertain their potential risk and select the most appropriate method of testing in each case.

HC Marbella International Hospital (Marbella High Care International Hospital)
Private Hospital Marbella, Calle Ventura del Mar, 11, 29660
+34 952 908 628
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HC Marbella International Hospital (Marbella High Care International Hospital)

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