THE EFFECT OF RECOMBINANT-HUMAN-ERYTHROPOIETIN TREATMENT ON TUMOR RADIOSENSITIVITY AND CANCER-ASSOCIATED ANEMIA IN THE MOUSE

Recombinant human erythropoietin (rHuEpo) has recently become availabl e for the treatment of chronic anaemia, including that associated with cancer. Carcinoma NT in CBA mice causes a progressive anaemia which c an be overcome by daily injections of recombinant human erythropoietin (rHuEpo). This model was used to study the effect of haematocrit on t umour blood flow, growth rate and radiosensitivity, in mice with haema tocrits ranging from approximately 38% (control) to 65% (20 U/day rHuE po). Tumours showed a small but significant slowing in growth rate wit h higher haematocrit. In vitro studies showed rHuEpo had no direct eff ect on the growth of NT cells. Tumour-blood flow was measured by two m ethods in each mouse (Xe-133 clearance and Rubidium-86 uptake). Blood flow showed a tendency to decrease with increasing blood viscosity alt hough this effect was not significant despite the large differences in haematocrit. Although tumour doubling time was prolonged despite the large differences in haematocrit. Although tumour doubling time was pr olonged with increasing radiation dose, from 0 (sham irradiated) to 35 Gy, haematocrit was not found to influence the growth delay. This was attributed, to adaptation of the tumour during the relatively slow ch ange in the haematocrit. rHuEpo is being considered for clinical use i n anaemic cancer patients. Our data suggest that this treatment will c orrect haematocrit with no effect on tumour radiosensitivity.