Different prognostic implications of hepatic metastasis according to front-line treatment in non-small cell lung cancer: A real-world retrospective study

Background: Although liver metastasis occurs in approximately 15% of metastatic non-small cell lung cancer (NSCLC) patients with poor prognosis, its prognostic effect in patients who receive immunotherapy is unclear. This study aimed to verify the effects of liver metastasis on the prognosis of metastatic NSCLC patients according to their first-line treatment. Methods: Patients who were initially diagnosed with stage 4 NSCLC from January 2015 to December 2019 were analyzed in this retrospective real-world data-based study. The patients were divided into three groups according to the type of first-line chemotherapy they received: cytotoxic, targeted, and immunotherapy. Prognosis was then compared depending on the presence of liver metastasis in each treatment group. Results: Among the 1,470 patients, 723 (49.2%) received cytotoxic chemotherapy, 678 (46.1%) received targeted therapy, and 69 (4.7%) received immunotherapy as their first-line chemotherapy. A total of 234 (15.9%) patients had liver metastasis at the initial diagnosis. The mean patient age was 63.7 years, and 59.1% were male. There was no difference in overall survival (OS) in the immunotherapy group in patients with or without liver metastasis (11.7 vs. 13.0 months, P=0.968); however, patients with liver metastasis had worse outcomes in the cytotoxic and targeted therapy groups compared to patients without liver metastasis. Furthermore, in patients with liver metastasis, the immunotherapy group had a longer OS than the cytotoxic chemotherapy group (11.7 vs. 4.4 months, P<0.001). Liver metastasis was associated with poor outcomes (hazard ratio of 1.438), as were age, male sex, bone, adrenal gland, or soft tissue metastasis, and three or more metastatic sites; however, lymph node, brain, collateral lung, and pleura metastasis did not affect prognosis. Conclusions: Although liver metastasis was associated with poor outcomes, it did not affect prognosis in patients who received immunotherapy.