HEMATOLOGICAL TOXICITY OF CRANIOSPINAL IRRADIATION

Background: To assess the frequency and severity of myelosuppression d ue to cranio-spinal irradiation either alone or in combination with ch emotherapy and to identify patients at high risk of haematological tox icity who may require supportive therapy. Materials and Methods: Betwe en 1965 and 1994, 210 patients received cranio-spinal axis (CSA) radio therapy as a component of treatment for primary CNS tumours at the Roy al Marsden Hospital. Full blood counts (FBC) were obtained before, dur ing and after radiotherapy in 200 patients. Haematological toxicity wa s graded according to the WHO criteria and duration was measured from the onset of grades 3 and 4 toxicity until recovery to grade 2. Result s: Sixty-six (33%) patients developed grades 3 and 4 haematological to xicity. Nadir occurred during radiotherapy and was most frequent durin g the second week of spinal radiotherapy. Low haemoglobin and while ce ll counts prior to radiotherapy increased the likelihood of myelosuppr ession. Nine patients had febrile episodes requiring antibiotic therap y. Treatment was interrupted in 49 patients but treatment time was ext ended beyond 12 weeks in only 17 (8%) patients of which nine were due to haematological toxicity. Chemotherapy (vincristine) during radiothe rapy did not impact on haematological toxicity. Age and prior chemothe rapy were independent predictive factors for haematological toxicity. The relative risk of leukopaenia in children compared to adults was 7. 9 (95% CI 3.4-18.6%). Patients who received prior chemotherapy had a r elative risk of toxicity of 6.1 (95% CI 2.9-12.8%). Conclusion: One-th ird of patients undergoing CSA radiotherapy develop grades 3 and 4 hae matological toxicity. The risk is higher in children and in patients w ho receive chemotherapy prior to radiation. There was no treatment-rel ated mortality and only nine of 200 patients (9/60 of those with toxic ity) required supportive treatment for neutropaenic sepsis. The low in cidence severe haematological toxicity does not warrant routine use of haemopoietic growth factors during CSA irradiation and future studies should target high risk subgroups. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.