are used to orient regions (lobes or bronchopulmonary segments) of the lungs affected with sputum into positions whereby gravity can facilitate drainage 'downwards' toward the central airways.

tend to grow in the outer regions (periphery) of the lungs away from the large airways. For this reason, they are less likely to experience symptoms related to an airway obstruction such as a cough.

Lung cancer typically is diagnosed at a later stage than other malignancies, due to the lack of early warning indications. In 2020 it was China’s most common cancer and the leading cause of ...