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case_images: Summary of the diagnosis and treatment process.
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case_images: A 55-year-old male underwent thoracoscopic-assisted small-incision radical resection of lung cancer in October 11, 2017 after diagnosis of lung adenocarcinoma (stage pT1bN0M0, IA) ( Figure 1 ). His positron emission tomography (PET) CT scan suggested bone metastasis ( Figure S1 ).
case_images: Diagnosis of brain metastases. (A) On October 31, 2019, the magnetic resonance imaging (MRI) examination of the patient showed multiple brain masses including multiple metastases in the lateral ventricle, right frontal lobe, and cerebellar hemisphere. Diagnosis of leptomeningeal metastases. (B) On April 21, 2020, MRI T1 enhancement and FLARE examination showed that the cerebellar sulci had multiple line-like and spot-like enhancements, suggesting meningeal metastasis. (C) On April 30, 2020, retest of the cerebrospinal fluid (CSF) showed the presence of cancer cells with the characteristics of adenocarcinoma cells.
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case_images: October 12, 2019), the patient started to experience headache, blurred vision, and hearing loss. On October 31, 2019, his brain MRI exam showed multiple brain masses including multiple metastases in the lateral ventricle, right frontal lobe, and cerebellar hemisphere ( Figure 2A ). On 2020-4-21, his brain MRI ( Figure 2B ) showed multiple dot-line enhancements (masses) in the cerebellar sulci, suggesting meningeal metastasis. On 2020-4-30, the patient underwent cerebrospinal fluid (CSF) cytology examination and cancer cells were found in the cerebrospinal fluid, which was in line with the characteristics of adenocarcinoma cells ( Figure 2C ).
case_images: Gene detection diagram and levels of carcinoembryonic antigen (CEA) during treatment. (A) Gene detection diagram during the treatment was shown. Different colors represent different genes and different wave widths. The number on the vertical axis represents the mutation frequency (wave width). (B) The levels of CEA, including serum CEA and cerebrospinal fluid CEA, were shown.
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case_images: TP53 p.R273C and ERBB2 p.S442L ( Figure 3A ). The patient was then treated with whole brain radiotherapy (40Gy/20 fractions). The re-test of the CSF samples showed that the mutations included EGFR p.L858R, TP53, ERBB2, and others (October 28, 2021). ( Figure 3A ). In January 2021, due to the continued elevated levels of tumor marker carcinoembryonic antigen (CEA) in his CSF ( Figure 3B ) and based on his CSF genetic test results, his treatment was switched to dacomitinib (30mg po qd), olaparib (100mg po bid), anlotinib (8mg po d1-14,q3w), pemetrexed (500mg/m2, q3w), and temozolomide (200mg/m2 d1-5, q4w). His level of CEA was stable ( Figure 3B ), and his brain MRI showed no progression of the brain metastasis.
case_images: MRI imaging changes at different time points during the treatment process.
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case_images: The efficacy evaluation during the treatment period is shown in  Figure 4 .