Not all who smoke get lung cancer
. Similarly, not all cancer patients are smokers. The risk increases when your smoking index crosses 200 (It is defined as number of cigarettes per day multiplied by number of years smoked). You seem to have smoked little, so the risk is very low.
The chest tightness
is usually due to bronchitis, acid reflux
, sometimes angina (unlikely in your case). You are overweight
and you take alcohol. If you are also snoring at night, this may indicate sleep apnoea!
For the moment, get a X-ray chest done which should rule out cancer adequately and close the topic. Reduce weight and stop smoking/ alcohol abuse