Cancers of the soft tissues.

Soft tissue sarcomas are rare and occur more frequently among males (0.9-4.3 per 100,000 age adjusted to the world standard population) than females (0.7-2.6 per 100,000). The international variation in incidence is small, and little change has occurred over time. Mortality rates were half or less than half the incidence and increased slightly in some areas, which is easily explained by changes in classification, coding and diagnosis over time, as well as instability of rates due to small numbers. Survival, in particular comparing data from the 1950s and 1960s with those from the late 1980s, has improved slightly. However, these observations must be interpreted with caution inasmuch as according to the ICD, STS are classified both with specified organs and with the connective tissue. In view of the Danish experience, this fact alone may account for recorded differences in incidence (and thus mortality) of 1 and 4 cases per 100,000 per year. No major risk factor has been clearly identified for soft tissue sarcoma, although genetic traits and certain environmental agents such as ionizing radiation and agricultural chemicals seem to be involved in some cases. The recent rise in AIDS related Kaposi's sarcoma indicates the importance of further studies into the role of infectious agents and immunological mechanisms. Future trends in soft tissue sarcoma should be studied after separating these tumours into Kaposi's sarcoma and other relevant aetiological subgroups.