Dad had x-ray of shoulder & doctor found spot on lung-quarter size. they are doing full x-ray soon. is this likely cancer? could it be the scar on his

Maybe: This can be anything from old histoplasmosis, which is ubiquitous in much of the USA, to a scar from something-or-other, to real cancer. It is meaningless to give probabilities now. Especially if he's a smoker, it's cancer until proved otherwise. Truth is, today's radiologists can often tell. I hope this is settled soon and I am glad he has you during this stressful time.

A full x-ray is the : next step. A CT or MRI may follow. Usually a cancer diagnosis requires a piece of tissue be put under a microscope to see if it is benign or malignant. Be sure to follow-up with these diagnostic tests. If he has a prior chest x ray to compare it to this new full x-ray, it is very helpful to the Radiologist. Get that to the Radiologist, if possible. Any weight loss,night sweats, or any other sympt?