Please anyone knows....
I'm full trained outside USA in medical oncology and I did PhD and postdoctoral research fellowship in USA.
Anyone knows if do I have any chance to get any oncology fellowship without IM? or even less years of IM?
I already answered your question. It is theoretically possible to do just fellowship. But you'll have to find a program willing to take you. Heme/Onc is pretty competitive so the likelihood of finding a "good" spot is very low.
Your best bet to get "any" fellowship is to just apply to all of them (you've taken all 3 USMLE Steps, right?) and see what happens. Your best bet to get a "good" fellowship is to start at square 1 and do residency in the US.
Assuming that you can find a fellowship, if you want to practice in the US you will have to meet state licensure requirements which vary from one state to another and usually include take USMLE step 3 and sometimes will require residency so you may have to do fellowship first and THEN do residency. I think that some states have " exceptional" pathways to licensure in which they may recognize other training on case by case basis but that may be very difficult. I would recommend starting your search bu contacting the medical boards directly to know their criteria. Otherwise, it is residency and then fellowship or vice-versa.