<s>[INST] I have been diagnosed with asthmatic bronchitis after having a cold . When reading up on this illness I realized it is sometimes misdiagnosed and could be lung cancer . I am 25 and have smoked for 10 years on and off and I smoke less than 1/4 pack a day. What is the most effective monitoring of symptom to look out for or screening test to check for early stages of lung cancer? [/INST] Hello, There are several signs that are sometimes obvious that a malignancy is brewing such as constant cough, sputum mixed with blood, weight loss (very important), GI symptoms such as vomiting or constant sickness. Getting a chest X-Ray is the first investigation, but HRCT is more sensitive and can be done. The most important thing you must do is STOP smoking, and it does not matter if it is 1 or 20 cigarettes a day. Asthma/COPD is the obvious progression of lung pathology is you continue and finally ends up with cancer in some people. There is no reliable blood test for lung cancer as is there for some other organ-specific cancers so do STOP smoking. Thanks. </s>