What are the percentages it is cancer?

New to this website and community;  I have had chronic lymphocytic leukemia for 5 years.  Doing very well and, in fact, have been reclassified with MBL (monoclonal B lymphocytosis).  I am in a clinical study at NIH to track my progress, not having any chemo or radiation, only using CAM.  In a baseline CT scan this past week a 6mm spot was found on my lung. I was told to repeat the scan in 3 to 6 months (for growth).  My question is are there probabilities out there that it is or is not a secondary cancer?  I have had a few squamous cell skin cancers removed which are much more common in people with CLL.  Thanks for any input.