Therapeutic Resistance in G-CSF Producing Lung Cancer With EGFR Mutation.

Background/aim: Granulocyte colony-stimulating factor (G-CSF)-producing neoplasms are relatively rare; however, little is known on the clinical features of G-CSF-producing lung cancer harboring activating epidermal growth factor receptor (EGFR) mutations.

Case report: A 66-year-old female was definitively diagnosed with G-CSF-producing lung cancer that was positive for EGFR mutations. She repeatedly received epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), such as osimertinib and afatinib. However, she developed resistance to these molecular-targeting drugs within 2 to 3 months after immediate shrinkage. Thus, the patient was treated with chemoimmunotherapy including bevacizumab, and demonstrated a slight survival benefit.

Conclusion: Overall, G-CSF-producing lung cancers positive for EGFR mutations were resistant to different treatment modalities. Clinicians should be attentive to the potential resistance of G-CSF-producing EGFR mutant lung cancer to EGFR-TKI therapy.