e22531 Background: Multiple primary malignancies (MPMs) describe two or more primary tumors arising in a synchronous or metachronous manner in the same individual. Patients with a primary cutaneous melanoma are at high risk of developing MPMs. While melanoma and other tumors are highly immunogenic and may cause immune suppression at the individual level, the molecular underpinnings of immune suppression among patients with MPMs remains to be elucidated. Here, we attempt to describe this rare, but unique group of patients who have both advanced melanoma and at least one other primary malignancy. Methods: Patients with advanced melanoma (stage III-IV disease) and at least one other non-melanoma cancer were identified. Synchronous tumors were defined as those occurring within 6 months of the first primary cancer. Metachronous tumors were defined as those occurring at least 6 months after the first primary cancer. Patients who had melanoma first, before a second cancer, and those who had a prior other cancer first, followed by melanoma were included. Overall survival (OS) describes the time from diagnosis of the first primary cancer to death due to any cause. Two-sample t-tests were used to compare OS among these groups with statistical significance if p < 0.05. Results: Eleven patients with MPMs including advanced melanoma were identified. Advanced melanoma was the first primary tumor in 5 patients and the second primary in 6 patients. A synchronous second primary was observed in 4 patients, whereas a metachronous second primary was observed in 7 patients. The median time between the diagnosis of the first primary cancer to the second primary was 21 months and the median time between the diagnosis of a second primary to a third primary was also 21 months. The median OS for all patients was 73 months. The median OS for synchronous MPMs and metachronous MPMs were 64.5 months and 82 months, respectively (p = 0.013). For patients with melanoma as the first primary cancer, the median OS was 73 months, compared to 87 months when melanoma was the second primary cancer (p = 0.785). Among all 11 patients, two are deceased, while the remaining patients are under surveillance. Among the remaining 9 patients, 100% have no evidence of disease with respect to melanoma. Conclusions: Despite the favorable outcomes from early detection and the advanced treatments available such as immunotherapy, a robust treatment plan should be in place when advanced melanoma is diagnosed as a synchronous tumor or second primary cancer. Further research is warranted since there are no guidelines available for the treatment of MPMs.
A Case Series of Multiple Primary Malignancies Among Patients With Advanced Melanoma
