I may have cystic fibrosis, copd or lung cancer (my maternal grandfather had stage iv lung cancer), how to know?

Focused physical exm: Start with a physical exam from your primary care physician. Focus and feel free to ask your doctor about your concerns. Specifically report any breathing or pulmonary symptoms you might be having, such as shortness or breath, easily getting tired with minimal activity or chronic persistent coughing. There are simple, non-invasive tests that can function as initial screening and diagnostic tools.

Chest X ray first: You are too old for Cystic Fibrosis. (usually causes death by age 30). A chest xray, and possibly a chest ct would rule out almost all lung cancers, and help evaulate for COPD. Pulmonary Function Tests would be a better test for COPD.

Diagnosis....: There are diagnostic tests your doctor can order to be sure you don't have these conditions. For example, pulmonary function testing will show chronic obstruction if you have COPD and a chest CT can help rule out lung cancer and there is specific testing for cystic fibrosis. If you are smoking, you need to quit ASAP to lower the risk of COPD and lung CA. See a lung doctor for the testing you need

Not Cystic Fibrosis: If you had cystic fibrosis you would know it long before your 40th birthday. COPD is a common cause of shortness of breath in smokers or ex-smokers who have significant exposure to cigarette smoke. COPD is easy to quantify with simple pulmonary function tests. Lung cancer is also a risk in people with exposure to cigarette smoke. See your primary care doctor to have symptoms looked into.