Sarcomas account for over 20% of all pediatric solid malignant cancers and less than 1% of all adult solid malignant cancers. The vast majority of diagnosed sarcomas will be soft tissue sarcomas, while malignant bone tumors make up just over 10% of sarcomas. The risks for sarcoma are not well-understood. We evaluated the existing literature on the epidemiology and etiology of sarcoma. Risks for sarcoma development can be divided into environmental exposures, genetic susceptibility, and an interaction between the two. HIV-positive individuals are at an increased risk for Kaposi’s sarcoma, even though HHV8 is the causative virus. Radiation exposure from radiotherapy has been strongly associated with secondary sarcoma development in certain cancer patients. In fact, the risk of malignant bone tumors increases as the cumulative dose of radiation to the bone increases (p for trend <0.001). A recent meta-analysis reported that children with a history of hernias have a greater risk of developing Ewing’s sarcoma (adjusted OR 3.2, 95% CI 1.9, 5.7). Bone development during pubertal growth spurts has been associated with osteosarcoma development. Occupational factors such as job type, industry, and exposures to chemicals such as herbicides and chlorophenols have been suggested as risk factors for sarcomas. A case-control study found a significant increase in soft tissue sarcoma risk among gardeners (adjusted OR 4.1, 95% CI 1.00, 14.00), but not among those strictly involved in farming. A European-based study reported an increased risk in bone tumors among blacksmiths, toolmakers, or machine-tool operators (adjusted OR 2.14, 95% CI 1.08, 4.26). Maternal and paternal characteristics such as occupation, age, smoking status, and health conditions experienced during pregnancy also have been suggested as sarcoma risk factors and would be important to assess in future studies. The limited studies we identified demonstrate significant relationships with sarcoma risk, but many of these results now require further validation on larger populations. Furthermore, little is known about the biologic mechanisms behind each epidemiologic association assessed in the literature. Future molecular epidemiology studies may increase our understanding of the genetic versus environmental contributions to tumorigenesis in this often deadly cancer in children and adults.

The peak incidence of osteosarcoma (OMIM 259500) occurs during the pubertal growth spurt.^1-3 Osteosarcoma risk factors include tall height,^4,5 high birth-weight,^4,5 previous radiotherapy,⁶ and at least 8 established cancer predisposition syndromes,^7,8 including autosomal-dominant disorders (Li-Fraumeni syndrome [OMIM 151623],^9,10 hereditary retinoblastoma [OMIM 180200],^11,12 and Diamond-Blackfan anemia [OMIM 105650]^13,14) and autosomal-recessive disorders (primarily DNA helicase disorders,^15-18 such as Rothmund-Thomson syndrome [OMIM 268400], RAPADILINO syndrome [OMIM 266280], Werner syndrome [OMIM 277700], and Bloom syndrome [OMIM 210900]). Candidate gene and genome-wide association studies suggest that common single-nucleotide polymorphisms are also associated with osteosarcoma,^19-21 affirming a complex underlying architecture for its genetic etiology but one that appears to be weighted disproportionately toward rare variants.

Susan Slager and colleagues report a meta-analysis of genome-wide association studies for chronic lymphocytic leukemia (CLL). They identify nine loci newly associated with CLL. Genome-wide association studies (GWAS) have previously identified 13 loci associated with risk of chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL). To identify additional CLL susceptibility loci, we conducted the largest meta-analysis for CLL thus far, including four GWAS with a total of 3,100 individuals with CLL (cases) and 7,667 controls. In the meta-analysis, we identified ten independent associated SNPs in nine new loci at 10q23.31 (ACTA2 or FAS (ACTA2/FAS), P = 1.22 × 10−14), 18q21.33 (BCL2, P = 7.76 × 10−11), 11p15.5 (C11orf21, P = 2.15 × 10−10), 4q25 (LEF1, P = 4.24 × 10−10), 2q33.1 (CASP10 or CASP8 (CASP10/CASP8), P = 2.50 × 10−9), 9p21.3 (CDKN2B-AS1, P = 1.27 × 10−8), 18q21.32 (PMAIP1, P = 2.51 × 10−8), 15q15.1 (BMF, P = 2.71 × 10−10) and 2p22.2 (QPCT, P = 1.68 × 10−8), as well as an independent signal at an established locus (2q13, ACOXL, P = 2.08 × 10−18). We also found evidence for two additional promising loci below genome-wide significance at 8q22.3 (ODF1, P = 5.40 × 10−8) and 5p15.33 (TERT, P = 1.92 × 10−7). Although further studies are required, the proximity of several of these loci to genes involved in apoptosis suggests a plausible underlying biological mechanism.