Stage IVA lung adenocarcinoma with solitary brain metastasis: pCR after brain surgery, chemoradiation, immunotherapy, and lobectomy

What happened, in summary

This 71-year-old man had smoked for 51 years and presented with worsening cognitive function and left-sided leg weakness. At another hospital, imaging showed pulmonary adenocarcinoma in the right upper lobe with a solitary synchronous brain metastasis in the right frontal lobe. The cancer was staged cT1bN0M1b, Stage IVA. Treatment began with local control of the brain disease: a neurosurgeon resected the right frontal brain tumor, and he received intensity-modulated radiotherapy to the brain, 50 Gy in 25 fractions. Pathology confirmed the brain tumor was metastatic lung adenocarcinoma. Molecular testing found no driver gene mutations or translocations, while immunostaining showed PD-L1 positivity in 75% of the tumor. He then received 4 cycles of carboplatin, pemetrexed, and atezolizumab. Chest CT showed the thoracic lesion had decreased, meeting partial response criteria. Brain imaging showed disappearance of the metastasis and improvement in surrounding edema. PET also showed reduced uptake in the primary thoracic lesion. Because the primary lung lesion remained controlled and no new distant metastases appeared, his team performed robot-assisted right upper lobectomy for local control. Pathology of the lung specimen showed no viable tumor cells, a pathologic complete response, and the final stage was ypT0N0M1b Stage IVA. He recovered without complications and continued atezolizumab maintenance, 1200 mg every 3 weeks. As of May 2024, after 13 maintenance cycles and 1 year of treatment, no recurrence had been observed. This sequence is notable because a solitary brain metastasis and the primary lung tumor were both treated aggressively after systemic therapy had brought the disease under control.