GSTM1 and neoplasm: However, we noticed a trend with respect to tumor hemoglobin concentration, as tumors treated with SBRT had a relative increase in Hb concentration at the two-week time point (mean fold change: 2.03) while tumors treated with SBRT and immunotherapy had a relative decrease in hemoglobin concentration at the two-week time point (mean fold change: 0.56) (Figure 5b).