All testing on heart neg/cxr clear.. have chest pains and feel burning sensation chest area on and off. is this a precursor to lung cancer?

More likely heartbrn: Off and on burning sensation just beneath the middle or to the left of the breast bone is more often heartburn than anything else. Nicotine or caffeine intake, acidic foods, reclining with a full stomach, all can aggravate that process. Lung cancer is unlikely to give you this pattern of symptoms if it give any warning symptoms at all.

No: Your symptoms most likely suggest some gastric reflux symptoms. Your chest xray is clear which is re-assuring. If you are a heavy smoker a ct scan for lung cancer screening may be appropriate;.