Background: Osteosarcoma as second malignancy of childhood cancers rarely occurs, and its clinical characteristics are unclear.
Methods: Patients with osteosarcoma occurring as second malignancy of childhood cancers were retrospectively surveyed.
Results: Of 323 patients with osteosarcoma registered in the database, 10 (3.1%) had a past history of childhood cancers. The mean age at the onset of the first childhood cancer was 2.7 years, and the diagnosis of the first childhood cancer was adrenocortical carcinoma, malignant teratoma, ovarian carcinoma, Ewing's sarcoma, and rhabdomyosarcoma in 1 patient each, and retinoblastoma in 5 patients. Osteosarcoma as second malignancy occurred 14.6 years after the first childhood cancer on average. Seven patients were alive and 3 died. In 1 patient, the cause of death was related to a complication of treatment for the first childhood cancer. Except for this patient, 7 (77.8%) of 9 patients survived with no disease (mean follow-up period: 10.9 years).
Conclusions: Attention should be paid to complications of treatment for the first childhood cancer in the treatment for osteosarcoma occurring as second malignancy. The prognosis of osteosarcoma as second malignancy of childhood cancers may be more favorable than that of conventional osteosarcoma.