The story provides a review of early research examining an experimental blood test for the detection of melanoma. The addition of the comments from an unaffiliated expert place the research into context and provide important caveats to the study.
But early on the story makes a bold claim that the test could save thousands of lives, yet in many cases, early detection of cancer does not guarantee a longer, healthier life. That’s an important reality that should be shared with readers. The story also would have been stronger had it discussed the downsides to screening tests — notably the risk of false-positive and false-negative results — and the risk of overdiagnosis. For example, this dermatologist’s perspective would have been a refreshing take to include in this story.
Melanoma is the most dangerous form of skin cancer. Early detection is essential for good clinical outcomes. A blood test to easily detect the disease would be a welcome addition especially in those areas with a high prevalence of the disorder. However, there are many pitfalls to consider, and news stories must be cautious not to oversell the benefits and downplay the risks.
This test, since it involves ten separate autoantibody antigens is likely to be expensive. A test to determine breast cancer recurrence risk, Oncotype DX cost approximately $3,000. It is unclear how often a blood test for melanoma would need to be repeated, so the cost will be an important consideration, and should have at least been acknowledged.
The story provides both sensitivity and specificity for the test and notes that both need to be in excess of 90% for it to be useful.
Of course, there is an assumption that the test–if proven to be validated–would reduce deaths from melanoma due to early detection. That will take a lot more research to determine. “Early detection saves lives” is not always true.
Like many other stories about screening tests, the reader is not provided with any comments on the potential harms. Even with a 90% sensitivity and specificity (a high mark for such a test), there would be many people with both false positive and false negative results. Read more about this issue in our primer: Understanding medical tests: sensitivity, specificity, and positive predictive value
These cancers are frequently overdiagnosed, so a diagnostic test that finds a lot of low-risk cancers could be harmful by leading to overtreatment. Ideally, we want know that the test is leading to finding early-stage, high-risk cancers that require and would benefit from treatment.
The story provides a modest amount of information on the study methods and carefully describes the results. The comments of Dr. Moffat place the research in proper context, “We need to know how accurate it is, if it can save lives, and how it could work in practice. So, although a blood test to find skin cancer earlier is certainly exciting, research in this field still has hurdles to overcome…”
However, one important point to make about this level of research — the scientists were using blood samples from confirmed melanoma patients. Will the blood test’s performance hold up when used widely and only among people with unknown cancer status?
The study was conducted in Australia, where melanoma is very prevalent. The story provides statistics without hyperbole.
We did not detect any conflicts of interest that should have been disclosed, though it would have been useful to explain how the study was funded (a grant from the Australian government). The story provides comments from Dr. Moffat, an unaffiliated expert who places the tests and the results in context.
The story does a good job in providing the current diagnostic methods.
The story seemed to give mixed messages about the value of screening with the new blood test. An investigator is quoted as noting that current methods of melanoma detection are expensive and invasive, involving a trip to a clinician, who must biopsy the lesion to discover whether it is cancerous. Elsewhere, the release notes that you still need a biopsy to evaluate a positive blood test. Clearly, a clinician visit and biopsy will always be required to diagnosis a cancer.
Aside from self-examination, having a clinician perform a skin exam during routine examinations is another alternative to the blood test–but is not addressed in the story.
It is clear from the story that the tests are in the experimental stages and not available commercially.
This report appears to be the first of its kind related to melanoma.
The story does not appear to rely on a press release.
Systematic, Criteria-Driven
The tale of two “negative” studies. Or, how spin is applied to make research findings look more impressive. A must read. https://johnmandrola.substack.com/p/the-tale-of-two-negative-studies
The @nytimes chose to interview one of the editors of the @AnnalsofIM (publisher of this paper) who "gushed with extraordinary glee: It’s huge! There are very few things that reduce your mortality by 30%."
Turns out coffee is not one of those few things despite all that glee. https://twitter.com/garyschwitzer/status/1533202075928215558
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