Brother In Law Has Been Taking OxyContin For 3 Years.

Brother in law has been taking OxyContin for 3 years. Initially given for shingles pain. Doctor continued given him the meds. He has been diagnosed with cancer but what type has not been determined yet. He has been spitting up large amount of blood for 4 month. It may be coming from lung cancer, but, we think he is indeed hooked on the OxyContin. And, if he is to take one he may take three at one time. I do not know the dosage. My question....could this blood ( in clots) be coming from him overtaking these meds? Thanks