Amazingly, almost 25% of all the people whoe are being diagnosed may have shown no symptoms of lung cancer at the time the disease was found. As for many other cancers too, lung cancer is usually detected incidentally during an x-ray that was performed for an unrelated reason.

However, the majority obviously does develop lung cancer symptoms and their direct causes can be categorized into three areas: activity of the primary tumor, effects of distant tumors (metastases) in other parts of the...