Sat 21 Jul 2018
The test which detects autoantibodies to a panel of cancer antigens in some patients with melanoma may eventually provide an alternative to microscopic examination of a skin biopsy.
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In recent days Australian and international media have highlighted a study from West Australian researchers reporting their work in developing a blood test that can detect early-stage melanoma skin cancers. Currently melanoma skin cancers are detected by visual inspection of the skin either by being noticed by the affected person or by a doctor doing a skin examination. Confirmation of the diagnosis of melanoma can only be made by microscopic examination of a skin biopsy by a pathologist.
The Australian researchers have used a microarray containing 1627 different human proteins, many of them known to be involved in the development or progression of different types of cancers. By testing blood samples from people with melanoma and healthy controls the researchers were able to identify autoantibodies in the subjects’ blood against some of these protein antigens.
All samples from both healthy controls and people with melanoma contained a range of autoantibodies. Using statistical methods, the researchers were able to identify a panel of 10 autoantibodies that enabled them to identify most people with melanoma. This combination of markers identified 79% of people with melanoma including very early stage melanoma skin cancer. This means that of every 100 people with melanoma who are tested, 79 will be identified and 21 (1 in 5) will be missed. The specificity or true negative rate of the test was 84%. This means that of every 100 people without melanoma who are tested, 84 will be correctly identified and 26 (1 in 4) will be labelled as possible melanoma. These figures are encouraging but not ideal for a screening test.
The authors also point out that so far melanoma patients have only been compared with healthy controls. In practice some of the people being tested will have other diseases such as different kinds of cancer and other disorders such as autoimmune diseases which may have the potential to cause false positive results and reduce the specificity of the test even further.
Nevertheless, this is an important advance as this is the best performing blood test developed so far. Further work may be able to improve the test performance and allow it find a place in clinical usage.
The Age: WA researchers develop 'world-first blood test' to catch melanoma: ECU
CNN: Experimental blood test could detect melanoma skin cancer early, study finds
Oncotarget: A diagnostic autoantibody signature for primary cutaneous melanoma
(the full research article)