The importance of re-biopsy in the era of molecular therapy for lung cancer

Introduction. Recent epidemiological data highlight that lung cancer incidence and mortality rates remain alarmingly high globally for both men and women. Over the last 10 years, the evolution in treatment corresponds to identifying specific driver mutations within lung tumors and developing inhibitors targeting these mutations. Case outline. A 73-year-old woman was diagnosed with lung adenocarcinoma staged as T4N2M1b at the Institute for Pulmonary Diseases of Vojvodina in February 2019. The Oncology Board recommended molecular analysis of the tumor and palliative radiation therapy for spinal metastases. Molecular testing identified an exon 19 deletion in the epidermal growth factor receptor (EGFR) gene. Following radiation treatment of the spine metastases, the patient began treatment with afatinib in May 2019. After 35 cycles of the aforementioned therapy, in April 2022, a computed tomography scan of the thorax and abdomen showed that the disease had progressed. Despite three liquid biopsies failing to detect the T790M mutation, a subsequent bronchoscopy and tissue re-biopsy confirmed its presence, prompting the initiation of osimertinib treatment. Twelve months into osimertinib therapy, the patient continues to be monitored. Conclusion. EGFR is a crucial predictive biomarker for non-small cell lung cancer. The introduction of specific tyrosine kinase inhibitors ? first-generation agents like gefitinib and erlotinib, second-generation afatinib, and introduction of third-generation (osimertinib or lolatinib) when initial treatments are met with resistance, has led to significant therapeutic breakthroughs.