OBJECTIVE: To evaluate the necessity of weekly monitoring by means of leukocyte and platelet counts of patients with head and neck, chest, and pelvis cancer submitted to conventional radiotherapy. MATERIALS AND METHODS: A hundred and one adult patients with cancer of head and neck (n = 11), chest (n = 35) and pelvis (n = 55), submitted to radiotherapy were assessed by means of leukocyte and platelet counts on a weekly basis, with a comparison between the results before and during the treatment and in correlation with the area treated, patient's sex and age group. RESULTS: The most significant decrease in leukocytes was observed in the fourth week, when lymphocytes, total leukocytes, neutrophils, monocytes and platelets presented a decrease of 53.5%, 26.8%, 19.4%, 22.2% and 14.6%, respectively, in comparison with the values found before the beginning of the therapy. Geometric means for pelvis during the treatment were lower than those for chest, and head and neck. Lymphocytes demonstrated to be more sensitive to radiation therapy. No alteration was found in leukocyte or platelet counts in correlation with patients' sex or age. CONCLUSION: Based on the results of the present study, weekly leukocyte and platelet counts do not seem to be useful in the assessment patients submitted to conventional radiotherapy for localized cancer.

Keywords: Leukocyte count, Complete blood count, External beam radiotherapy, Radiotherapy toxicity