Purpose: Reliable data on familial risks are important for clinical counseling and cancer genetics. However, population-based studies on familial soft tissue tumors are limited, which we will examine.
Methods: Adjusted standardized incidence ratios (SIRs), calculated from the nation-wide Swedish Family Cancer Database, were used to measure the familial risk.
Results: There were 17 offspring-parent pairs with concordant soft tissue tumours, the SIR was increased but not significant. Offspring soft tissue tumors were associated with paternal prostate and endocrine gland tumors and Hodgkin's disease. Offspring myxosarcoma was associated with paternal endocrine gland tumors. Offspring fibrosarcoma was associated with parental stomach cancer and liposarcoma was associated with parental bladder cancer and maternal breast cancer. Leiomyosarcoma was associated with maternal breast cancer. The associations of myxosarcoma with melanoma and liposarcoma with non-Hodgkin's lymphoma were noted among siblings.
Conclusions: The present study showed that familial clustering of soft tissue tumors was limited to specific subtypes. Because of multiple comparisons, some of observed associations may be negative. Aggregation of melanoma and myxosarcoma among siblings may suggest Werner syndrome. A very small proportion of soft tissue sarcomas may be explained by Li-Fraumeni syndrome. Other novel associations, such as offspring liposarcoma with parental bladder cancer, and liposarcoma and non-Hodgkin's lymphoma among siblings, may be related to other unidentified familial diseases.