While melanoma in situ is easily cured by surgery, the diagnosis may have an impact on how patients view themselves.
Melanoma in situ (MIS; or stage 0 melanoma) represents half of the diagnosed melanomas in the United States, according to Adewole “Ade” Adamson, MD, MPP. “Given MIS’s increasing prevalence, it is important to understand how a diagnosis of MIS impacts the feared outcome of cancer diagnosis: death,” he says. “Prior to our study, there was little information about mortality and/or survival statistics related to MIS.”
The incidence rate for MIS was 0.5 per 100,000 individuals in 1975, Dr. Adamson points out. There since has been a 50-fold increase, with more than 25 per 100,000 individuals.
For a population-based cohort study published in JAMA Dermatology, Dr. Adamson and colleagues aimed to assess mortality and factors linked with mortality after a diagnosis of MIS. The researchers used the SEER program database, essentially the cancer registry of the United States. “This database allowed us to study three important cancer survival statistic: relative survival, melanoma-specific survival, and standardized mortality ratios,” Dr. Adamson says.
Participants ‘Live Longer Overall Than Those in the General Population’
Among a cohort of 137,872 patients with MIS, the study team found that 15-year melanoma-specific survival was 98.4% (95% CI, 98.3%-98.5%). However, “the 15-year relative survival, meaning overall survival relative to similar individuals in the population without MIS, was 112.4% (95% CI, 112.0%-112.8%; Figure),” Dr. Adamson notes.
“The MIS survival statistics suggest that patients with a diagnosis of MIS have an increased, but low, risk for dying of melanoma and live longer overall than age/sex/race-matched people without MIS. This suggests MIS may mostly be a marker of health-seeking behavior resulting in the detection of low-risk disease. Factors linked with mortality following MIS include older age, male sex, and acral melanoma histology.”
Interpretation of MIS as Cancer May Contribute to Overdiagnosis
The study’s findings potentially lend further credence to the idea that MIS is not an definite precursor to invasive melanoma, Dr. Adamson explains. “The rise in MIS may be contributing to melanoma overdiagnosis, the detection of very low-risk disease that would not cause symptoms or death if left alone,” he says. It is also critical to contemplate the potential harmful effects of an MIS diagnosis, he adds, particularly the psychological effects of being labeled as a patient with cancer, including the fear of cancer recurrence and anxiety over lifelong skin examinations.
Dr. Adamson and colleagues concur that these data should allay the fear that many patients with an MIS diagnosis have about survival. “While their chance of dying from melanoma is elevated (albeit low in absolute terms), patients’ overall survival is significantly higher than their peers without MIS,” he says. “We need to understand the psychological impact on patients diagnosed with MIS. While it is a cancer that can be easily cured by surgery, the diagnosis may have an impact of how patients view themselves in the world.”
