Chronic myeloid leukemia during osimertinib treatment in a non-small cell lung cancer patient: A case report.

Case summary: A 45-year-old man presented with a 4.0cm × 4.0cm mass in right lower lobe and a right lower lobectomy was performed. The pathological diagnosis from the right lower lobe mass was adenocarcinoma with an EGFR mutation in exon 21 (L858R). He chose osimertinib as postoperative adjuvant treatment. Eight months after the administration of osimertinib, leukocytosis was detected and we diagnosed the patient with chronic myeloid leukemia (CML). After the diagnosis was made, the patient started the treatment of flumatinib immediately, and treatment of osimertinib continued. After one month treatment, leukocytosis was completely relived. The patient was receiving treatment of osimertinib and flumatinib simultaneously with both lung cancer and leukemia well-controlled, and the side effects were tolerable. Conclusion: Hemogram of non-small cell lung cancer (NSCLC) patients should be carefully monitored during EGFR-TKIs treatment. While there is a potential association between EGFR-TKIs and the development of hematologic abnormalities such as CML, more evidence is needed to clarify whether EGFR-TKIs have a leukemogenic effect. For patients with CML during EGFR-TKIs treatment, osimertinib combined with flumatinib may be an effective treatment modalities and the side effects can be tolerated.