Exposure to chemotherapy and posttreatment G-CSF was significantly associated with an increased risk of sMN in DLBCL [HR, 4.56; 95% confidence interval (CI), 3.23–6.43; P < 0.0001], FL (HR, 6.79; 95% CI, 4.48–10.28; P < 0.0001), and multiple myeloma (HR, 8.77; 95% CI, 5.21–14.79; P < 0.0001). The gene discussed is CSF3; the disease is diffuse large B-cell lymphoma.