Incidence patterns of soft tissue sarcomas, regardless of primary site, in the surveillance, epidemiology and end results program, 1978–2001: An analysis of 26,758 cases

Soft tissue sarcomas (STS) are a heterogeneous group of uncommon tumors that show a broad range of differentiation that may reflect etiologic distinction. Routine tabulations of STS are not morphology-specific. Further, the lack of inclusion of sarcomas arising in all organs in most standard evaluations underestimates the true rates. We analyzed the 1978-2001 Surveillance, Epidemiology and End Results program incidence rates of STS regardless of primary site, except bones and joints, using the 2002 criteria of the WHO classification. There were 26,758 cases available for analysis. Leiomyosarcomas accounted for 23.9%, malignant fibrous histiocytomas 17.1%, liposarcomas 11.5%, dermatofibrosarcomas 10.5%, rhabdomyosarcomas 4.6% and angiosarcomas 4.1%. Almost half (47.9%) of the sarcomas arose in the soft tissues, 14.0% in the skin and 7.0% in the uterus. Overall, incidence rates were highest among black women (6.26/100,000 woman-years) and the lowest among white women (4.60/100,000). Age-adjusted rates increased at 1.2% and 0.8% per year among white males and females, respectively, both trends statistically significant, while rates among blacks declined slightly. About 40% of leiomyosarcomas among women were uterine in origin, with a black/white rate ratio of 1.7. This rate ratio increased to 2.0 when we accounted for the lower prevalence of intact uteri among black compared to white women. Total STS rates rose exponentially with age. Rates for both uterine leiomyosarcoma and dermatofibrosarcoma increased rapidly during the childbearing years, peaking at about age 40 and 50, respectively. Incidence patterns of STS varied markedly by histologic type, supporting the notion that these tumors may be etiologically distinct.