Hematologic changes during prostate cancer radiation therapy are dependent on the treatment volume

To assess hematologic changes of modern prostate radiation therapy (RT) comparing different target volumes.

Blood samples were evaluated before (T1), during (T2-T4) and 6-8 weeks after (T5) RT in a group of 113 patients. Whole-pelvic RT up to 46 Gy was applied in 27 cases. The total dose to the prostatic fossa (n = 46)/prostate (n = 67) was 66/76 Gy.

Erythrocyte, leukocyte and platelet levels decreased significantly relative to baseline levels at T2-T5. Neoadjuvant hormonal therapy had an impact on hemoglobin levels before and during RT. The cumulative incidence of grade 2 leukopenia was 15 versus 2% (p = 0.02) and grade 2 anemia 8 versus 0% (p = 0.03) with versus without whole-pelvic RT, respectively. Lymphocyte decrease was larger at times T2-T5 (36 vs 3% grade 3 toxicity; p < 0.01).

Prostate RT has a small but significant and longer effect on the blood count. Lower lymphocyte levels need to be considered when larger volumes are treated.