Hi and welcome to HCM.
It doesnt soound like emphysema
or cancer.You would have more intensive symptoms such as dispnea, blood coughing and it would be seen on chest xray. Bronchitis
is also something serious and you should stop or reduce smoking
definitely. Bronchitis can lead to emphysema and serious respiratory failure
and lung infections. You should start with some medicines which helps you clear phlegm and open your bronchis.ALso do frequent pulmonary check ups and everything will be fine,you dnot have to worry about cancer.
Wish you good health.