Is all bronchial tube cancers malignant?

Yes. When you use the word cancer, it implies malignant. However, there are many tumors (abnormal growth of cells) that are not cancer/malignant.
See answer. Malignancy as defined is the tendency of a medical condition, especially tumors, to become progressively worse and to potentially result in death. Cancers, certainly can fall into the category of "malignant." not all cacers ultimately result in death though! certain bronchial tube cancers may be treated medically and surgically, depending on the stage of the cancer with a good prognosis.