A 63-year-old woman with lung adenocarcinoma faced a confusing medical mystery. Her doctors saw a new lesion in her brain and assumed it was cancer spreading from her lungs. However, the tumor grew in a way that did not match the expected behavior of her original disease. This unusual pattern raised a critical question: was this a metastasis or a completely new primary cancer?
Pathological examination confirmed the diagnosis was a primary glioblastoma, a rare and aggressive brain tumor. The patient received a combination of surgery and medications including ensartinib and lorlatinib. Despite these treatments, she developed progressive weakness in her left limbs. The lesion continued to grow, and she passed away ten months after the brain cancer diagnosis.
This case report highlights a vital lesson for oncologists. When a patient with a known malignancy develops a new intracranial lesion, the treatment response might not match the biology of the original tumor. Doctors should consider the possibility of a second primary cancer rather than assuming the new growth is a metastasis. Timely pathological confirmation and a multidisciplinary review can help reduce diagnostic delays and improve treatment selection for patients facing these complex situations.