Individuals who have been exposed to asbestos, diesel exhaust and other chemicals, such as railroad workers, have an increased risk of getting cancer. Catching cancer early may help increase rates of beating the disease.
Because of this, it is very important for anyone who has had occupational exposure to asbestos and/or diesel fumes to tell their doctor about those exposures. Your doctor may choose to have you undergo regular chest x-rays to monitor for changes in your lungs, or give you regular PFT tests to examine and track changes in your pulmonary function. Or your doctor might choose to monitor your health without these tests.
Regardless, it is a decision that you should make with your doctor, after making sure that your doctor knows about your history to asbestos and/or diesel fumes.