Decline of the red blood cell count in patients receiving androgen deprivation therapy for localized prostate cancer: impact of ADT on insulin-like growth factor-1 and erythropoiesis.

Objectives: To elucidate the mechanism of blood hemoglobin loss in patients with prostate cancer during androgen deprivation therapy (ADT), and to examine the activity of the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) axis during ADT, which plays an important role in hematopoiesis.

Methods: A total of 83 patients with localized prostate cancer, who received ADT, were prospectively studied on the basis of their blood samples at the baseline and after ADT for 6 months.

Results: Before ADT, the IGF-1 level was correlated with the red blood cell (RBC) count (Spearman's rank correlation coefficient analysis [rs]=0.315, P=.011), hemoglobin (rs=0.278, P=.018), and mean corpuscular volume (rs=0.266, P=.020), but such relationships disappeared after ADT. After ADT, the serum IGF-1 level increased compared with that at the baseline (21+/-6 vs 18+/-5 nmol/L, respectively, P<.001), but no change was observed in the serum GH level (P=.691). There was no difference between erythropoietin and interleukin-6 concentrations before and after ADT (P=.852 and P=.208, respectively). The hemoglobin concentration and RBC count declined after ADT compared with those before treatment (P<.001 for each). Although the mean corpuscular volume declined after ADT (P=.002), the mean cell hemoglobin was comparable between before and after ADT (P=.676).

Conclusions: Despite the unaffected GH, erythropoietin, and interleukin-6 levels, the serum IGF-1 concentration was elevated by ADT. Even with the increased IGF-1 level, the RBC count and hemoglobin concentration declined after ADT. IGF-1 in the bone marrow erythroid progenitor cells might be functionally inactivated during ADT.