Technology advances have made it possible to detect some cancers without a traditional biopsy; a start-up company in California is potentially making it possible to detect skin cancers without a biopsy AT ALL. DermTech, a La Jolla-based company founded by doctors and melanoma specialists, is attempting to break the traditional mold of cutting off and cutting out suspicious skin lesions for a more targeted approach to finding moles that may become melanomas.
New technology for cutless biopsies
The product itself is quite simple: clean the suspicious lesion with gauze, take an adhesive patch (roughly the size of a nickel), rub it on several times, trace the mole’s shape, remove, and place on the sample collection card. Do this up to four times per card, seal the card up, drop it in the mail to California, and a few days later, you have an “ALL CLEAR!!” or a “Mr. Sharpe, we are going to need you to come back in for further testing…”
The product’s selling points center on the non-invasiveness of the procedure – why cut, when you can simply lift a sample off of your stratum corneum (that’s fancy Latin for the very outer layer of your skin, consisting of flattened dead cells that eventually flake off)? This is helpful in a number of scenarios; medically for people who are anti-coagulant or are at increased risk for infection or scarring, and cosmetically for any place that is sensitive. Think face, neck, between fingers, and any other place you wouldn’t want to get cut. If a melanoma is found, a shave or punch biopsy is then conducted to confirm.
More than one use
It also can potentially detect melanomas before they become actual melanomas, and before they appear that way to a dermatologist’s trained eye. The process behind how the Pigmented Lesion Assay (PLA) works is pretty technical, but they are looking to see if two genes are “expressed” or show up on the test of the skin (PRAME and LINC00518). The presence of these genes is an indication the lesion may be cancerous, as both genes are elevated in melanoma. If the test comes back positive for either, follow up work is necessary.
The first, obvious question is, “Does this work?” There is evidence to suggest that it does. A clinical trial of the Pigmented Lesion Assay published in October 2018 shows it being reliable, with the PLA-positive test results identifying melanoma in about one-third of the cases. More importantly, there were no true negatives in limited follow up – according to the study, the PLA didn’t miss anything. It will be nice to see how those evolve over a longer period of time (one year follow-up data to be published in February 2019), but at least initial indications are the PLA caught all the melanoma moles.
This product could have a huge impact
Dermatologist and DermTech CMO Dr. Burkhard Jansen described the impact of the DermTech product, “While patients and physicians like the non-invasive nature of the Pigmented Lesion Assay, they see the test’s reliability as the game-changing parameter”. The DermTech team provided numbers that sound great: the negative predictive value (the chance that a negative test is actually melanoma) is less than 1%, compared with about 17% for traditional histopathology. 91% sensitivity – the “true positive” rate, or percentage of positives correctly identified as positive. 69% specificity – the “true negative” rate, or percentage of negatives correctly identified as negative. This last number seemed a bit confusing, but has to do with the difference in how traditional histopathology tests are measured (by structural change) vs. the PLA (in the expression of the genes, which can occur prior to the structural change).
The follow up is, “Why would I want to use this instead of the traditional biopsy?” It initially seemed as the process was an elective option to save some vanity. If you’ve have a few of those traditional cuts, though – especially when a scalpel starts inching close to head and neck level – then it’s all of the sudden less vain, more “keep the knife (and the anesthesia needle) away from me!!” Add to this the possibility of finding melanomas/potential melanomas BEFORE they actually become melanoma, and its value suddenly skyrockets. From personal experience, I can say with certainty I would much rather remove this disease early on (stage 1 five year survival rate: 99%) than worry about missing it until it gets worse (stage 4 five year survival rate: 20%).
The catch is cost
Alas, one the biggest barriers to entry are “Who pays for this?” A challenge to adoption is getting insurance companies to reimburse, but DermTech has capped the out of pocket for insured patients at $50 (the cash price for the assay is $250). This challenge is shared by many new technologies, and the DermTech team seems committed to making their product available by capping the cost and filing appeals for denied lab work. Other technologies, like dermoscopy, faced similar challenges in adoption and reimbursement before becoming part of main-stream melanoma detection.
Not enough evidence
I brought the product to my dermatologist, who, to a bit of dismay, dismissed it as unproven. He pointed out that the human intellect can be more reliable than technology advances (and used Siri and Alexa as examples of great tools with limitations), with the implication that a doctor with a scalpel was in much better position to detect potential melanomas than a sample of epidermis shipped off to some lab he wasn’t familiar with. The patient side of me had a split reaction – I was thankful he would take any suspicious mole so seriously but discouraged he wasn’t open to advancements in care. Other patients and dermatologists I spoke with expressed similar hesitations on the reliance of technology.
As you head into the office for your next skin checkup (and you ARE doing that, every six months, right?) be sure and ask your doctor how up to date they are on the latest detection methods. Chances are they don’t know about some new ways, like the PLA, to detect melanomas. In the end it is your skin on the line, and up to you to push for every possible way to stay cancer-free.
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