Other primary systemic cancers in patients with melanoma: Analysis of balanced acral and nonacral melanomas

Background: Although other primary systemic cancers in patients with melanoma have been studied, there have been few focusing on acral melanomas. Objectives: We assessed other primary systemic cancers in patients with acral and nonacral melanomas. Methods: We analyzed other primary cancers in 452 patients with melanoma from 1994 to 2013. Metachronous cancers were defined as those given a diagnosis more than 2 months after diagnosis of melanoma. The others were considered prechronous or synchronous cancers. Results: Among 51 cases of other primary cancers, gastrointestinal cancer (35.3%, n = 18/51) was the most common, followed by thyroid (17.6%), lung (11.8%), and breast (5.9%). Those were more prevalent in the acral melanoma group (12.8%, n = 31/243) compared with the nonacral melanoma group (9.6%, n = 20/209). Of 23 cases of metachronous cancer, the risk was the highest in bone marrow, followed by oral cavity, bladder, colon, lung, and thyroid. Among 28 cases of prechronous or synchronous cancers, gastrointestinal tract (35.7%, n = 10/28) was the most common site, followed by thyroid (17.9%), breast (10.7%), and lung (7.1%). Limitations: The study is limited by a small number of patients. Conclusion: Careful follow-up and imaging studies are necessary for early detection of other primary cancers and metastatic lesions in patients with melanoma.