Incidence of multiple primary malignancies among patients with bone cancers in Sweden

Purpose: The present study aimed at quantifying risks for second malignancies in patients with bone cancers, and risks for second bone cancers after other primary tumors. Methods: Adjusted standardized incidence ratios (SIRs) were used as a measure of risk. Results: Among 2,546 primary bone cancer patients, a total of 171-second malignancies occurred. Besides second bone cancers, other cancer sites with an increased SIR were the soft tissues and endocrine glands. The overall risk of second malignancies following Ewing's sarcoma was 5.63, followed by chordoma (1.99), osteosarcoma (1.54), and chondrosarcoma (1.51). Patients diagnosed before age 20 years showed an increased SIR of 3.11. The increased occurrence of second bone cancers was noted after the cancer sites of upper aerodigestive tract, kidney and nervous system. Conclusions: The incidence of second primary malignancies in bone cancer patients was moderately increased. Among histological types, Ewing's sarcoma showed the highest risk of developing second cancers. Young age was also associated with an increased risk. Besides therapeutic effects, the observed excesses of a second bone or soft tissue tumor may be related to Li-Fraumeni syndrome. Increases at other sites may be related to unknown factors or spurious findings.