That is a good article; the take home point from it is: "However, as mentioned above, it remains unclear whether PPARs act as oncogenes or as tumor suppressors." PPARs in general are controversial medications regardless of receptor type.
Avandia (rosiglitazone) is a PPAR-gamma receptor agonist used for the treatment of diabetes that was banned for about two years but recently regained FDA approval after it was thought that it increased the risk of heart attacks and strokes. Actos (piaglitazone) is another drug that has been shown to have some strange and counterintuitive adverse effects; but is also still used to treat type 2 diabetes.
Strangely, fibrates, which bind the PPAR-a receptor, don't have the same side-effect profile as the delta and gamma receptor agonists.
In any case, GW certainly may end up having a side-effect profile that could prevent approval but it has been shown to be extremely effective in cutting and IMO doesn't carry any more risk than other medications that are used for this role. Most fat burners that are stronger than ECA (clen, T3, DNP) have more defnitively shown harm, and obviously many legal agents have much stronger evidence showing their carcinogenesis (tobacco, alcohol, salted fish, aniline dyes)
