Multiple primary
malignancies (MPM) are described as two or more primary
tumors within the same individual. The impact of MPM on the tumor microenvironment among patients with
melanoma is poorly understood. Here, we describe this unique group of patients who have both advanced
melanoma and at least one other primary
malignancy and report their survival outcomes. In this study, patients with advanced
melanoma and a second primary
malignancy were identified. Medical records were reviewed for
cancer treatment history. Kaplan-Meier methods were used to derive survival curves and estimate overall survival (OS), and log-rank tests were used to compare OS. Among 11 MPM patients, the most common non-
melanoma cancers were breast (n = 3) and thyroid (n = 3). Median OS was 153.5 months for all patients. Median OS for synchronous MPM (sMPM) and metachronous MPM (
mMPM) were 83.1 and 196.7 months, respectively (p= 0.10). Median OS was not reached when
melanoma was diagnosed first, and 153.5 months when diagnosed second (p= 0.45). For six patients receiving
immunotherapy for
melanoma, there was a 100% complete response rate. In conclusion, patients with
melanoma are at risk of secondary
malignancies, including breast and
thyroid cancer. The timing of secondary
malignancies may impact prognosis. Further study of the impact of
immunotherapy on MPM is warranted.