The statement of which part of lung adenocarcinoma is the most serious is wrong in itself. Lung adenocarcinoma mainly spreads through blood and lymph nodes, and once metastasis occurs, it will lead to low immunity and jeopardize the life of the organism. There are two main ways of lung adenocarcinoma spreading, one is hematogenous metastasis, which metastasizes to distant organs such as brain, liver and bones, and can cause cerebral edema, generalized bone pain, hepatic coma, etc. In serious cases, it can cause tumor rupture and lead to death, all of which are serious, and there is no saying to which organ is the most serious one. Another way of metastasis of lung adenocarcinoma is lymph node metastasis, which mainly invades the lymph nodes around the bronchus of neighboring lung segments or lobes, or invades mediastinal and paratracheal lymph nodes, causing life-threatening airway compression. For lung adenocarcinoma, one should seek medical treatment in time and keep a good mind.