When it comes to medical procedures, everyone has their own definition of acceptable risk. Sadly we're then overruled by faceless bureaucrats at the US Food and Drug Administration (FDA) and similar government bodies - people who have only their own interests in mind, and suffer no consequences from making useful medical technologies illegal or too expensive for commercial use. Fortunately, the FDA doesn't rule the world: there are regions in which medical regulations are less onerous and therapies less costly, and these locations are only a plane flight away.
People who undertake medical tourism for stem cell therapies are demonstrating their own risk preferences: balancing the plausible expected benefits based on what is presently known of the science and the outcomes (in the absence of rigorous trials) against the cost and estimated risk. For stem cell treatments perhaps the largest inherent risk for early stage therapies is that of cancer resulting from the activities of transplanted cells. Work in the laboratory suggests that this risk is generally lower than first thought, but it still exists.
The world of cancer treatments is, meanwhile, changing profoundly, gearing up for a new generation of therapies that will displace chemotherapy and radiotherapy. Reprogramming immune cells or introducing targeted viruses and nanoparticles to seek out and kill cancer cells with few side-effects will be the standard operating procedure twenty years from now - and probably available outside the US in a decade. In early trials and the laboratory, these technologies are already showing impressive results.
Improvements in cancer treatment - leading to the introduction of robust therapies that can clear most common forms of cancer quickly and without accompanying illness - will, I think, go hand in hand with a far greater demand for and use of very aggressive stem cell treatments. Things like periodic infusions of massive numbers of immune cells cloned from a patient's own cells, done not just for people with medical conditions, but for the healthy as a beneficial preventative measure. Similarly, why boost regeneration and tissue maintenance via stem cell therapies only in the sick and the wounded? That makes sense if there is a significant risk associated with treatment, but in a world in which cancer is merely troublesome, why not make stem cell therapies a part of general health maintenance?
These are the sort of shifts in the cost-benefit picture of regenerative medicine that will emerge over the next couple of decades, driven by a growing ability to control the undesirable aspects of cellular biology, such as cancer.