Balancing prevention and overdiagnosis in skin cancer screening
A recent editorial published in JAMA Dermatology discussed the balance between prevention and overdiagnosis of skin cancer. This comes in response to the U.S. Preventive Services Task Force concluding for the fourth time in a row that visual skin cancer screening has insufficient evidence to support its population-wide benefit. How do we know when we’ve crossed from prevention to overuse, and is there anything we can do to keep the balance?
Early detection is important, but how do we screen responsibly?
It makes logical sense that catching cancer early before it spreads will reduce cancer deaths. In fact, I have personal experience with skin cancer. At 19, I had a small melanoma mole removed from my shoulder that I could barely see and would never have identified as problematic. While I’m at high risk of melanoma due to my pale skin and family history, it was not found at a dermatologist’s office. It was caught by the women’s health provider at my university during an unrelated check-up. My mole was likely melanoma in situ and presented no immediate threat to mortality, though I’m grateful to have the peace of mind that it’s gone. Essentially, my early melanoma was excised before it could have gotten worse.
However, my experience doesn’t apply to everyone, nor does it indicate that universal screening is a beneficial policy. As Dr. Adamson notes in his editorial, melanoma screening so far has resulted in increased rates of melanoma diagnosis, without having a subsequent impact on mortality from melanoma– a classic sign of overdiagnosis. This shows that we need more research around the “natural history” of melanoma — how a cancer progresses (or does not progress) from early to late-stage, so we can better identify early-stage cancers that are dangerous.
We can also do a better job of identifying those at higher risk of skin cancer and establishing screening guidelines for these patients. Logistically, we don’t have enough dermatologists to routinely screen everyone, so we need some way to triage. Currently, there is no consensus among dermatologists about who to screen and when, making it harder to study whether or not screening is working.
Another consideration is the type of skin cancer. Patients with darker skin are less likely to develop UV-based skin cancer but more likely to develop acral lentiginous melanoma. Screening guidelines should match this knowledge accordingly.
Overdiagnosis has harm too. Targeting our interventions can help.
If the benefits of screening are minimal, we have to be aware of the risks to better evaluate the balance. Screening for cancer seems may seem like a risk-free endeavor, but there are many potential physical, psychological, and financial risks. While infrequently discussed, there is the potential for harm through diagnosis. A diagnosis of cancer is scary and intimidating and can cause psychological distress. It opens the door to further cascade events such as biopsies and surgeries, which have risks of complications. And apart from the general requirements of taking time off and physically showing up to the dermatologist’s office, screening costs money. Dr. Adamson notes the need for more research on this topic to fully evaluate the benefits and harms. “In melanoma, the potential harms of screening, including those caused by overdiagnosis, have not yet been fully elucidated,” he writes.
With the current evidence, it appears that we should be moving towards a more targeted screening approach. We obviously don’t want to abandon all preventative measures – after all, the goal is early detection to save lives – but striking the balance between prevention and overdiagnosis is nuanced. More research is needed to better inform best practices for skin cancer screening and determine its value across the population. As Dr. Adamson says, “Patients deserve better.”