A team of Australian researchers has created a blood test capable of diagnosing melanoma based on the presence of just 10 antibodies created by the immune system in response to the malignancy.
With a sensitivity of 79 percent and specificity of 84 percent – meaning it would fail to catch 21 percent of cases and 16 percent of positive results would be false positives – the new panel is reportedly the first lab-based method for objective skin cancer detection that's accurate enough for use in a real-world clinic setting. Though subsequent studies must validate these findings, the test could save tens of thousands of lives and millions in healthcare costs.
"Patients who have their melanoma detected in its early stage have a five-year survival rate between 90 and 99 percent," first author Pauline Zaenker said in a statement. Once metastasized, cutaneous melanoma – the most aggressive of all skin cancer types – carries a 15 to 20 percent five-year survival rate. "This is what makes this blood test so exciting as a potential screening tool because it can pick up melanoma in its very early stages when it is still treatable," Zaenker said.
Currently, screening for melanoma and other skin cancers involves periodic visual examinations by increasingly overburdened dermatologists, followed by invasive biopsies for suspect moles and lesions. Due to the inherent limitations of this approach and lack of access to specialists, many instances of melanoma are not caught until it’s dangerously late. Each year, approximately 350,000 new cases of melanoma occur and 60,000 people die from the disease worldwide. Australia and New Zealand bear a disproportionate number of cases because they host large Caucasian populations living with high sun exposure.
Writing in the journal Oncotarget, Zaenker and her colleagues explain that many past investigations have identified certain molecules, called biomarkers, that circulate in the bloodstream of melanoma patients. Yet none of the laboratory panels using these biomarkers were sensitive enough to catch the disease right after malignant cells first arise.
Hoping to finally fulfill this crucial requirement, the authors analyzed blood serum samples from 124 patients with recently diagnosed non-metastasized cutaneous melanoma and 121 healthy controls. They identified a total of 1,627 autoantibodies (antibodies that target one’s own tissue as opposed to a foreign pathogen), then used rigorous statistical methods to separate out a small set of antibodies that are consistently produced early in the disease progression.
“This melanoma autoantibody signature may prove valuable for the development of a diagnostic blood test for routine population screening that, when used in conjunction with current melanoma diagnostic techniques, could improve the early diagnosis of this malignancy and ultimately decrease the mortality rate of patients,” they noted.
A three-year-long clinical trial to evaluate the efficacy of the test is now in the works. Until then, the researchers urge people to remain vigilant about moles, freckles, and sunspots.
And always remember to wear sunscreen.