Chronic Myelogenous Leukaemia Following S-1 THerapy for Rectal Cancer: A Case report

ABSTRACT Introduction Therapy-related leukaemias are the one of the most common second malignancies. However therapy-related chronic myelogenous leukaemia (CML) is far more rare than therapy-related acute myeloid leukaemias or myelodysplastic syndromes. Herein we report a case of secondary CML, who had a past history treated with S-1 as post-operative therapy for rectal cancer. Case report A 59-year-old male was referred to our hospital because of leukocytosis on October 2011. His laboratory findings showed a white blood cells of 14 100/ml with 11% basophils, 7% eosinophils, 0.5% myelocytes, 66.5% neutrophils. His haemoglobin level was 13.9 g/dl and his platelet count was 393 000/ml, and his serum level of lactate dehydrogenase was 341 IU/l. He had a past history of rectal cancer received abdominoperineal resection in July 2008, and was subsequently treated with oral anti-metabolite S-1 for a year (total dosage of 33 600 mg). Bone marrow aspiration showed hypercellular bone marrow without blast increase, and karyotype analysis revealed 46,XY,t(9;22)(q34;q11.2) [20]. A diagnosis of therapy-related CML was made because of his past history of S-1 therapy. The patient was started on dasatinib therapy and rapidly achieved complete haematological response. Discussion S-1 is among the most effective anti-cancer agents for various carcinomas such as gastric cancer, lung cancer and biliary tract neoplasms. And for colorectal cancer, S-1 is recommended as a suitable treatment of adjuvant therapies. To best of our knowledge, only few cases of therapy-related CML following fluoropyrimidines therapy have been described. The frequency, clinical course and prognostic value of therapy-related CML has not been clarified yet because of its rarity, and further accumulation of cases is necessary for evaluation of the therapeutic outcome of therapy-related CML patients.