Which symptom is commonly associated with lung cancer?

A change in coughing habits is commonly associated with lung cancer due to the disease's impact on the respiratory system. Lung cancer can lead to several changes in the way a person coughs, such as a persistent cough that worsens over time or the presence of blood in the cough, which is notably significant. Patients might experience a new cough after a history of smoking or a change in a long-standing cough, signaling a need for medical evaluation.

The other options provided do not typically relate to lung cancer. Persistent headaches may arise from various conditions, but they are not a hallmark symptom of lung cancer itself. A sudden loss of vision could indicate a neurological issue or an eye condition rather than lung cancer. Unexplained weight gain is also not a symptom associated with lung cancer; rather, weight loss is more commonly observed in individuals suffering from this disease as it progresses. Thus, the change in coughing habits is an essential sign that could warrant further investigation for potential lung cancer.