Within 14 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (up to 14 days before treatment initiation) Within 14 days of treatment initiation:\r\nHemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 10 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L (without transfusion or growth factor support/erythropoietin [EPO] dependency) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 (except as noted) days of planned treatment initiation: Hemoglobin >= 9.0 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L, performed within 10 days of treatment initiation, without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 14 days of treatment registration: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 14 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) within 14 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 28 days of treatment initiation) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 28 days of study registration Performed within 10 business days of treatment initiation with the exception of beta- HCG (72 hours), if applicable: Hemoglobin >= 8 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment). Performed within 10 days of treatment initiation: Hemoglobin ? 9 g/dL or ? 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), should be performed within 10 days of treatment initiation Hemoglobin >= 8 g/dL without transfusion or erythropoietin (EPO) dependency Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 10 days of treatment Hemoglobin ? 9 g/dL or ? 5.6 mmol/L within 21 days of treatment initiation without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Performed within 10 days of treatment initiation: hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 10 days of treatment initiation) Within 5 days prior to the start of study treatment: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment). Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 14 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) To be performed within 14 days of treatment initiation: hemoglobin ? 9 g/dL or ? 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment). Within 14 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment). Obtained =< 14 days prior to registration: Hemoglobin > 9.0 g/dL or >= 5.6 mmol/L without transfusion or (EPO) erythropoietin dependency (within 7 days of assessment) Within 10 days prior to on-study date: Hemoglobin ? 9 g/dL (or ? 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL without transfusion or erythropoietin (EPO) dependency within 7 days Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 days of treatment initiation: Hemoglobin ? 9 g/dL or ? 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin ? 9 g/dL or ? 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 10 days of treatment initiation) Performed within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L\r\n* Patients cannot have received transfusion or erythropoietin (EPO) within 7 days of the hemoglobin (Hgb) lab test Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 8 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 10 days of treatment initiation Obtained =< 28 days prior to registration: Hemoglobin >= 9.0 g/dL without transfusion or erythropoietin (EPO) dependency (=< 7 days prior to assessment) Performed within 7 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 8 g/dL without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 14 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 10 days of treatment initiation Performed within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 14 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 14 days of registration Performed within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 28 days of registration) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (within 10-15 days of treatment initiation) Hemoglobin >= 8 g/dL without transfusion or erythropoietin (EPO) dependency within 7 days performed within 7 days of treatment initiation performed within 7 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), during screening and on cycle 1, day 1 Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) within 14 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 14 days of assessment) (performed within 10 days of treatment initiation) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin: >= 9 g/dL or 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Completed within 10 days of SBRT treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency\r\n(within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 8 g/dL without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 10 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 8 g/dL without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin ? 9 g/dL OR ? 8 g/dL if anemia due to iBCL, without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), should be performed within 10 days of treatment initiation Hemoglobin >= 7 g/dL or >= 5.6 mmol/L with transfusion or erythropoietin (EPO) dependency REGISTRATION TO TREATMENT (STEP 1): Hemoglobin (Hgb) >= 9.0 g/dL OR >= 5.6 mmol/L without transfusion of erythropoietin (EPO) dependency, within 14 days prior to first dose of pembrolizumab REGISTRATION TO TREATMENT (STEP 2): Hgb >= 9.0 g/dL OR >= 5.6 mmol/L without transfusion of EPO dependency, within 14 days prior to first dose of pembrolizumab Within 10 days of treatment initiation: hemoglobin >= 9 g/dl without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 28 days of treatment initiation Within 10 days of treatment initiation: Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin (Hgb) > 9 g/dL (without transfusion or erythropoietin [EPO] dependency within 7 days of assessment) Hemoglobin >= 9.0 g/dL (5.6 mmol/L or 90 g/L) without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) obtained =< 28 days prior to registration Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 10 days of treatment initiation) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 8 g/dL without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 8 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (within 14 days prior to day 1 of protocol therapy) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 10 days of treatment initiation) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), performed within 10 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment), should be performed within 28 days of treatment initiation, unless otherwise indicated Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) within 7 days of treatment initiation Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment) (performed within 10 days of treatment initiation) Hemoglobin (Hgb) >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment of Hgb), obtained within 14 days prior to C11-AMT PET scan Hemoglobin >= 9 g/dL or >= 5.6 mmol/L without transfusion or erythropoietin (EPO) dependency (within 7 days of assessment)