Many people have scars on their lungs as a result of prior infection of the lungs. Scarring, per se, is not a sign of cancer. The CT scan will provide a finer, much sharper image of the scar and enable the radiologist to say, with reasonable certainty, whether the shadow is a scar or possibly something else such as infection or a growth. That they called this a case of scarring makes it very unlikely that it would be a cancer.