http://www.ncbi.nlm.nih.gov/pubmed/21222203

Many people do not realize that what we call ‘aging’ is, by and large, a significant defense against carcinogenesis. The whole ‘stem-cell therapy’ medical tourism industry is, essentially, a ‘cancer party’, because stem cell injection is an unregulated industry, and the cells being injected are highly vulnerable to immediate carcinogenesis in adults.

The necessary biomarker assays have not been done, so there is no way to predict the results of the dynamism of the stem cells, and these are the source of the deadliest cancers. There are highly specific therapies that have some degree of history and testing that are worth the risk, but most of the other therapies are extremely dangerous.

The idea of longevity as a goal is, essentially, a recipe for cancer due to the nature of pluripotent cells, stem cells and telomerase.