Incidence and mortality of second sarcomas - a population-based study

Abstract

Background: Studies on second sarcoma in unselected populations of cancer survivors have not previously been published.

Methods: Second sarcoma was defined as a sarcoma following a previous invasive cancer. Patients with this malignancy were retrieved from the Cancer Registry in Norway for the period 1960-2007 among a total of 728874 cancer patients including 11 612 with a sarcoma. Changes in incidence and average annual percent change (AAPC) were studied with join-point analyses. Overall and sarcoma-related mortalities were assessed using the Kaplan-Meier and competing risk methods, respectively.

Results: A total of 900 second sarcomas were identified comprising 7.5% of all sarcomas. The AAPC of second sarcoma incidence was 6.2 (95% CI=5.7-6.7) as compared to 2.5 (95% CI=2.1-2.8) for all sarcomas and 2.5 (95% CI=2.4-2.6) for cancer in general. The annual incidence of second sarcomas doubled during the last decade of the study period. The distribution of histological subtypes was significantly different between second and sporadic sarcomas. The overall mortality was significantly higher and sarcoma-related mortality was significantly lower for patients with a second sarcoma compared to sporadic sarcoma.

Conclusions: There is an increasing incidence of second sarcomas among cancer survivors, and one may speculate a relation to the intensified use of cytotoxic treatment of the preceding malignancy. Sarcoma-related mortality after second sarcomas is significantly below that of sporadic sarcoma.

Keywords: Epidemiology; Histology; Incidence; Mortality; Radiation-induced; Sarcoma; Second malignancy.