Patient, female, 38 years old, was admitted to the hospital with left-sided chest pain for 1 week. The patient presented with left-sided chest pain before the obvious trigger on the fifth of July 2015, not severe, no obvious radiating pain, no fear of cold and fever, no hemoptysis and palpitation, went to a people’s hospital in Taizhou City, Zhejiang Province, on July 5, 2015, performed closed drainage of the chest cavity, and found suspected cancer cells, and then went to a hospital in Shanghai, China, on July 13, 2015, and performed PET/CT to see a soft-tissue shadow of the left lower lobe of the lung adjacent to the proximal margin, accompanied by a left pleural effusion, considering the possibility of lung cancer, left oblique fissure pleura and pleural metastasis (No. PET:15071314), on July 16, 2015, the patient was admitted to the hospital, the patient was admitted to complete the relevant examinations, and was given closed chest drainage, adenocarcinoma cells were found in the pleural fluid, the genetic test suggested that: the ROS1 positive mutation, combined with the systemic examination, the diagnosis of staging of adenocarcinoma in the left lung cT4N0M1a-IVA stage (left pleural) (ROS1 mutation). The patient’s July 17, 2015 chest CT situation. At that time, the NCCN guidelines did not recommend targeted drugs for ROS1 mutations. The patient is a mother of three children, the youngest of whom is in preschool this year, and is a hard-working housewife with an optimistic and cheerful personality. Her husband is a factory worker in the vicinity of her home, and the overall economic condition of the family is average. When her husband was told about the patient’s condition and the estimated median survival (estimated at the time to be 24-30 months), her husband’s tears crackled and fell involuntarily. “I’m going to treat her no matter what, but I’d also like to trouble the doctor to consider our actual financial situation.” Considering that bevacizumab antivascular drugs and crizotinib targeted drugs are very expensive and not covered by health insurance, the patient was treated with AC-T1 (pemetrexed 770mgd1, carboplatin 700mgd1) on July 21, 2015, and was given intrathoracic injections to control the pleural fluid, and was treated with AC-T2 on August 26, 2015 (pemetrexed 770mgd1, carboplatin 700mgd1) treatment. Chest CT was reviewed on September 20, 2015, and the efficacy evaluation was PR (partial remission), the left pleural lesion basically disappeared, and only the left upper lung lobe lesion remained. Stereotactic radiotherapy (40Gy/5Fx) was given to the left upper lung focal lesion and continued with AC-T3 (pemetrexed 770mgd1, carboplatin 700mgd1) on September 25, 2015 and AC-T4 (pemetrexed 770mgd1, carboplatin 700mgd1) on October 24, 2015 for chemotherapy. Patient’s chest CT on November 23, 2015 Chest CT was reviewed on November 23, 2015, and the efficacy was evaluated as PR (partial remission), with the left pleural lesion basically disappearing and a few residual lesions in the left upper lung. AC-T5 (pemetrexed 770mgd1, carboplatin 700mgd1) treatment on November 26, 2015 and AC-T6 (pemetrexed 770mgd1, carboplatin 700mgd1) treatment on December 23, 2015 were performed. Patient’s chest CT on January 26, 2016 Patient continued to be treated with pemetrexed (770mgd1) maintenance therapy, which was reduced from once a month at the beginning to once every 6 weeks. The patient’s pemetrexed (770mgd1) monotherapy maintenance treatment was well tolerated, with no significant nausea and vomiting or leukocyte decline or thrombocytopenia. Tumor marker carcinoembryonic antigen (CEA) has been reduced from 55.4ug/ml to 1.2ug/mL. from the related examination suggests a complete remission (CR) status. Chest CT on February 14, 2018 As for whether patients with this complete remission status need to stop chemotherapeutic drugs, many big names in the industry have been asked, but there is still no definite answer. According to/with reference to the experience/principles of maintenance therapy with targeted agents in advanced lung cancer, low-dose maintenance therapy may be a more appropriate treatment option. Patient continues maintenance therapy with pemetrexed (local hospital) once every 6-8 weeks. Patient’s chest CT on January 14, 2020 Patient adhered to continue 6-8 weekly pemetrexed (local hospital) maintenance therapy and has been living a completely normal life, coming to me for yearly reviews. This year it came a little late because of the epidemic, but the couple is very happy. “Our eldest child has graduated from college, and the youngest child has started junior high school, thank you doctor!” Patient’s Chest CT on June 12, 2022 Now that there are more and better medications available for this type of patient, we expect the patient to live a better and longer life! Treatment experience: the success of the patient’s treatment, in addition to the appropriate overall treatment strategy (systemic treatment + local stereotactic radiotherapy for oligo residual lesions), the patient’s positive and optimistic mindset, family support are very important, the whole treatment process, her husband has been with her no matter how busy to encourage her!