Abstract
The incidence of multiple malignancies among patients with malignant melanoma (MM) is 4.8%in Japan and has reportedly been as low as that of other skin cancers, although little has been known about the exact incidence. However, compared with other reports, the incidence of multiple malignancies seemed to be higher among patients with MM than among those with other malignancies in our hospital. Therefore, we performed an observational study to explore the incidence of multiple malignancies among the 130 patients with MM who were treated at our hospital from 2005 to 2012. Twenty (seven males and 13 females) out of the 130 patients with MM (15.4%) were treated in our facility for multiple malignancies. Fifteen cases (five males, 10 females) had double malignancies including MM; five (two males, three females) had triple malignancies. Of these twenty patients, fifteen (five males, 10 females) had malignancies preceding the MM, two (two females) had concurrent malignancies, and four (two males, two females) had subsequent malignancies. Four of the six patients who had concurrent malignancies developed subsequent malignancies within one year of the initial diagnosis, and two patients developed the second malignancy within five years. Therefore, it is important not only to check for the recurrence and metastasis of MM, but also to regularly and carefully follow up MM patients, because they appear to have a higher risk for other malignant tumors.
