Second primary malignancies among patients with soft tissue tumors in Sweden
Survival from soft tissue tumors (STTs) has been improved because of the successful treatment. One of the late sequelae in STT survivors is the development of a second malignancy. The present study aimed at quantifying risks for second malignancies in patients with STTs, and risks for second STTs after other primary malignancies. Adjusted standardized incidence ratios (SIRs), calculated from the Swedish Family-Cancer Database, were used as a measure of risk. Among 6,671 primary STT patients, a total of 650 second malignancies occurred. Besides second STTs, other cancer sites with an increased SIR were the nervous system, endocrine glands, skin (melanoma and squamous cell carcinoma) and prostate; the risk for non-Hodgkin lymphoma (NHL) was also increased. The overall risk of second malignancies decreased in the following order: fibrosarocma (1.63) > myxosarcoma (1.48) > leiomyosarcoma (1.44) > liposarcoma (1.21). An increased risk of second STTs after primary cancers of the bone, ovary, nervous system, cervix, thyroid gland, skin, endometrium, breast, upper aerodigestive tract, and after Hodgkin disease, NHL and leukemia was also noted. This study showed that the incidence of second primary malignancies in patients with STTs was increased, but the SIRs varied among specific cancer sites. Besides therapeutic effects, the associations between STTs and bone and nervous system tumors suggested that cancer syndromes, such as neurofibromatosis type 1 and Li-Fraumeni syndrome, may partly explain the excesses. The associations of STTs with cancers of the skin (squamous cell carcinoma and melanoma) and with NHL may be related to immunodeficiency.