NBN and osteosarcoma: Development of osteosarcoma was caused by different multiple factors, including genetic and environmental factors.2,14,15 Our study showed that GA+AA genotype of ERCC2 rs1799793 or GC+CC genotype of NBN rs1805794 were associated with an increased risk of osteosarcoma in females, which indicated that genetic synergistic effect between ERCC2 rs1799793 and NBN rs1805794 genetic variants and gender increases the risk of cancer.