Incidence of soft tissue sarcoma focusing on gastrointestinal stromal sarcoma in Osaka, Japan, during 1978-2007.

To clarify the incidence of soft tissue sarcoma and gastrointestinal stromal sarcoma in Osaka, Japan, we analyzed Osaka Cancer Registry's data. We identified a total of 6998 cases, except for those of bones and joints, during 1978-2007. The age-adjusted incidence rate of those sarcomas was 2.7 per 100 000 (male 2.8, female 2.6) person-years. The trend in the incidence for the last 10-year period (1998-2007) increased significantly overall and for females, while it was not significant for males. Except for cases not otherwise specified, the most prevalent histological subtype was leiomyosarcoma in digestive organs and gastrointestinal stromal sarcoma, followed by leiomyosarcoma excluding that in digestive organs and liposarcoma. Gastrointestinal stromal sarcomas were registered for the first time in 1988 and have increased since 1999, while leiomyosarcomas in digestive organs have decreased. Gastrointestinal stromal sarcoma might have been diagnosed as leiomyosarcoma in digestive organs before using immunohistochemistry.