Older age, subsequent melanoma increase risk for death in patients with melanoma in situ

Key takeaways:

• Mortality among patients aged 80 years or older was 7.4% vs. 1.4% in those aged 60 to 69 years.
• The risk for mortality increased after diagnosis of subsequent primary invasive melanoma (adjusted HR = 4.1).

Old age and the development of subsequent primary invasive melanoma are risk factors for death following a melanoma in situ diagnosis, according to a study.

“The incidence of cutaneous melanoma has rapidly increased during the past five decades,” Vishal R. Patel, BS, of Dell Medical School at The University of Texas at Austin, and colleagues wrote. “Once a rare tumor, melanoma is now the fourth most commonly diagnosed cancer in the U.S.”

Melanoma in situ (MIS) has disproportionately contributed to the rise of skin cancer incidence, according to the study. While the incidence rate was 0.5 per 100,000 individuals in 1975, it has increased 50-fold to more than 25 cases per 100,000 individuals.

In this population-based cohort study, Patel and colleagues evaluated the mortality and factors associated with mortality after diagnosis of MIS.

A total of 137,875 (mean age, 61.9 years; 46.4% women; 96.7% white) patients diagnosed with first-and-only MIS between 2000 to 2018 were included.

Results showed that 98.4% (95% CI, 98.3%-98.5%) of patients exhibited 15-year melanoma-specific survival compared with the 15-year relative survival of 112.4% (95% CI, 112%-112.8%).

While the standardized mortality ratio for melanoma was 1.89 (95% CI, 1.77-2.02), the all-cause ratio was 0.68 (95%CI, 0.67-0.7).

Specific factors that increased the risk for melanoma-specific mortality included old age (risk for mortality: 80 years, 7.4% vs. 60-69 years, 1.4%; HR = 8.2; 95% CI, 6.7-10) and acral lentiginous vs. superficial spreading histology (3.3% vs. 0.9%; HR = 5.3; 95% CI, 2.3-12.3), according to the researchers.

While the risk for developing a second primary invasive melanoma after primary MIS was low at 4.3%, the risk for mortality was higher among this population compared with patients without a subsequent melanoma (adjusted HR = 4.1; 95% CI, 3.6-4.6).

On the other hand, the risk for mortality among primary MIS patients decreased upon development of second primary MIS (aHR = 0.7; 95% CI, 0.6-0.9), which was experienced by 7.4% of patients.

“The melanoma cancer survival statistics reported in this cohort study are potentially important for patients and clinicians to accurately understand and put into perspective the risks associated with receiving a diagnosis of MIS,” the authors wrote. “Patients with a diagnosis of MIS have an increased but low risk of melanoma-specific mortality and live longer than people in the general population, suggesting significant detection of low-risk disease among health-seeking individuals.”