EGFR exon 19 lung adenocarcinoma with bone and brain metastases: brain lesions resolved on gefitinib

What happened, in summary

This 60-year-old man with a smoking history went to the hospital because of back pain and an abnormal chest X-ray. Bronchoscopic biopsy diagnosed lung adenocarcinoma. Whole-body PET-CT showed multiple bone metastases involving the lumbar spine and pelvic bone, and sequential brain MRI found multiple tiny enhancing nodules in the left occipital lobe and cerebellum. Molecular testing showed an EGFR exon 19 deletion, a mutation that can respond to EGFR-targeted treatment. He began gefitinib 250 mg daily. Because his brain metastases were small and not causing neurologic symptoms, whole-brain radiotherapy was deferred. Instead, radiotherapy was directed to the lumbar vertebra for painful bone involvement, while gefitinib treated the EGFR-mutant systemic disease. Follow-up brain MRI 1 month after gefitinib began showed interval regression of the brain metastases. After another 3 months, the metastatic brain lesions were no longer discernible on MRI. His course shows a strong intracranial response to gefitinib in EGFR-mutated lung adenocarcinoma. The lumbar vertebral metastasis was treated with radiotherapy for local symptom control, while the asymptomatic brain metastases improved on gefitinib without whole-brain radiotherapy. The response was clinically meaningful because it allowed him to avoid whole-brain radiotherapy during the reported course, limiting potential neurologic toxicity while still controlling visible brain disease. His back pain had prompted the diagnosis, and the combination of local spine radiation plus oral EGFR-targeted therapy addressed both painful bone disease and silent brain involvement. As of March 2014, his visible brain metastases had cleared on MRI after targeted therapy, and his metastatic lung cancer was responding well to treatment.