Incidence and survival of patients with primary gastrointestinal melanoma: a population-based study

Primary gastrointestinal melanoma (PGIM) has received more attention because of its inferior prognosis. Less is known about the incidence and survival rate of PGIM.

PGIM data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. The incidence was estimated by age, sex, race, and primary site. Trends in incidence were described as annual percent change (APC). Cancer-specific survival (CSS) and overall survival (OS) rates were estimated and compared using log-rank tests. Cox regression analyses were performed to identify independent prognostic factors.

The overall incidence of PGIM was 0.360/1,000,000 with a significant upward trend (APC = 1.77%; 95% CI 0.89%-2.67%, p < 0.001) from 1975 to 2016. Most PGIM occurred in the large intestine (0.127/1,000,000) and anorectum (0.182/1,000,000), and both incidences were almost 10 times higher than those of other sites, including the esophagus, stomach, and small intestine. The median survival time was 16 months (IQR, 7-47 months) for CSS and 15 months (IQR, 6-37 months) for OS, and the 3-year CSS and OS rates were 29.5% and 25.4%, respectively. Older age, advanced stage, absence of surgery, and melanoma in the stomach were the independent risk indicators of survival and associated with worse CSS and OS.

The incidence of PGIM has been increasing over the past decades and the prognosis is poor. Thus, further studies are warranted to improve the survival, and more attention should be paid to the patients that are elderly, patients with advanced stage, and patients with melanoma in the stomach.