Each marker has a specific sensitivity and specificity and methods for their determination are non-invasive and less expensive than other diagnostic methods. If a marker has low sensitivity and specificity, it is likely to go undetected in screening tests and this only becomes possible in combination with other diagnostic methods.

Tumour cells, despite their ability to form markers, do not always release them into the blood, hence there is a proportion of people with advanced cancer without significantly elevated markers in blood tests. On the other hand, disseminated cancer can result in elevated levels of several markers. It is extremely important here to seek the help of a specialist and to perform the necessary tests.[1]