<s>[INST] hi my bf smoked menthol cigs for over 20 yrs and stopped 6 yrs ago because he was told he had crystalized lungs and a couple yr later after having a chest xray for a infection the doc said his lungs were better now he has been told he has a nodule on right upper lobe of right lung. Docs tested him for valley fever and infections and had routine blood test that were negative. Hes just wondering the chances that its cancer its small but he has had a chronic productive cough for about three months.And he also was exposed to a lot of abcestis over 20 yrs ago. Hes 43. What are the chances of this being lung cancer? [/INST] Hi, Thanks for writing in. It is important to follow up the nodule in the lung. The size is important and if it is less than 8 mm then there is no serious concern. Should the nodule be closer to 3 cm in diameter then the probability of cancer is higher. What I intend to say is that a nodule must be followed up for a year or more depending on its doubling time. This is the time taken by the nodule to become twice its volume. A nodule that becomes twice its volume within 30 days or more than 6 months is most likely benign. Less than 30 days doubling is likely to be due to an infection. Rarely there are nodules due to bronchoalveolar cancer that might double over 2 years. Therefore, follow up is essential when there is a lung nodule. </s>