Incidence of multiple primary malignancies in a cohort of adult patients with soft tissue sarcoma.

Objective: Some studies to date have suggested the development of multiple primary malignancies in patients with soft tissue sarcoma. The current study was performed to quantify the risk of development of multiple primary malignancies in adult patients with soft tissue sarcoma.

Methods: A total of 406 consecutive patients who were diagnosed with soft tissue sarcoma were identified in the study analysis. The cumulative incidence of multiple malignancies was calculated by comparing Kaplan-Meier curves and log-rank tests from each histological type. A Cox proportional hazards model was used to estimate the influence on the hazard ratio (HR) of each variable.

Results: A total of 35 patients with soft tissue sarcoma (9%), having preceding (n = 15) and subsequent (n = 20) malignancies other than soft tissue sarcoma were documented. The 5- and 10-year estimated cumulative incidence of multiple primary malignancies were 7.6 and 12.3%, respectively. The hazard risk of multiple primary malignancies adjusted for potential confounding variables was significantly associated with age at diagnosis (HR = 1.51, P = 0.0019). The risk of multiple primary malignancies was also increased in patients with myxofibrosarcoma adjusted by the potential confounding variables (HR = 2.34, P = 0.048). The 5- and 10-year estimated cumulative incidence of multiple primary malignancies in patients with myxofibrosarcoma were both 16.9%.

Conclusion: The results of our study confirm that the risk of multiple malignancies appears to be impacted by age at the time of diagnosis of the first tumor and by the histological type of myxofibrosarcoma.