Melanomas diagnosed through routine skin checks are associated with significantly lower all-cause mortality, but not melanoma-specific mortality compared to other melanomas.
In a NSW study of 3,932 melanomas from 2,452 patients detected during 2006-2007, 35% were diagnosed during a routine skin check, 47% were patient-detected, and 12% were incidental findings.
The participants in the Melanoma Patterns of Care Study were followed for more than 10 years.
The study, published in JAMA Dermatology, said melanomas discovered in asymptomatic individuals through routine skin checks were thinner, less likely to have exhibited recent change, and associated with lower all-cause mortality than thicker lesions discovered initially by patients.
Men, people aged 50 years or older, those with a previous melanoma, those with many moles, or people living in non-remote areas were more likely to have melanoma detected during a routine skin check than self-detected.
Similar results were found for incidental detection of melanomas.
“Melanomas detected during a routine skin check were more frequently located on the back (356 of 858 [41%]) and more likely to have good prognostic features (nonulcerated, 636 of 858 [74%]; low mitotic rate <1 per mm2 , 317 of 858 [37%]),” the study said.
Melanomas detected in general practice were more likely to be patient detected (55%), but those detected in dedicated skin cancer clinics run by GPs and specialist dermatology clinics were more likely to be detected on a routine skin check (57% and 46%, respectively).
Most nodular melanomas were self detected.
The study found detection of invasive melanoma at a routine skin check was associated with 59% lower melanoma-specific mortality (subhazard ratio, 0.41; 95% CI, 0.28-0.60) and 36% lower all-cause mortality (hazard ratio, 0.64; 95% CI, 0.54-0.76) compared with patient-detected melanomas.
However when further adjusted, including for mitotic rate and ulceration, the association was no longer statistically significant for melanoma-specific mortality (subhazard ratio, 0.68; 95% CI, 0.44-1.03) but remained statistically significant for all-cause mortality (hazard ratio, 0.75; 95% CI, 0.63-0.90).
“The fact that routine skin-check melanoma detection was significantly associated with lower all-cause mortality but not melanoma-specific mortality in the fully adjusted analyses may reflect residual or unmeasured confounding from sociodemographic characteristics (such as education level), medical access, and health-seeking behaviors (such as physical activity) that are independently associated with both routine skin checks and overall mortality,” the investigators said.
Given concerns about overdiagnosis in cancer screening programs, the study said an RCT was required to provide definitive evidence on the value of skin cancer screening.
An accompanying editorial said the study affirmed data from previous studies that associated increased detection pressure with identification of thinner, less lethal lesions.
“What it is unable to confirm is that screening with routine skin checks saves lives,” it said.
“For many reasons, there has never been a randomised clinical trial of melanoma screening, nor is there one currently ongoing or planned. Thus, for the foreseeable future, our approaches to melanoma secondary prevention need to be based on indirect evidence and our understanding of biology and epidemiology.”
“The sum of that knowledge strongly suggests that there is a subset of melanomas that should be amenable to secondary prevention through early detection, but that there is a sizable reservoir of indolent melanomas that create a significant risk of overdiagnosis.”
The US authors said breakthroughs in our understanding of the biology of early melanoma will provide robust distinction between indolent and progressive disease.
“As we continue to promote melanoma awareness and employ more sophisticated technologies for early detection, it is critical that the melanoma and dermatology communities also promote strategies that increase the likelihood of saving lives while mitigating harms and costs.”