Is there a stem cell treatment cancer risk? Because of the press surrounding embryonic stem cells and misinformation spread by many in the stem cell research community, some patients still have a fear of potential cancer risks with an adult stem cell procedure. This fear extends to even the same day procedures, where it would be difficult to scientifically concoct a circumstance where cancer would be a concern. Now a new study, along with the safety data our group has already published, should put those fears to rest.
The concept that stem cells could cause cancer comes from embryonic stem cell (ESC) research. Because stem cells taken from a growing embryo are tasked with building a person, they can sometimes still try to build a person when used to treat a disease. The resulting mishmash of tissue is called a “teratoma”, a benign tumor that has many different types of tissue such as hair, teeth, muscle, bone, etc… Despite this weird fact, adult stem cells are a different animal altogether. They are not taken from a growing embryo, but instead from an adult. While ESCs do have a teratoma risk, no adult stem cell cancer risks have ever been published in human studies. In fact, getting adult stem cells to create a tumor in animals is tough. To make that happen, you usually have to add in things like “tumor conditioning media”, grow them for insanely long periods, and then put them into animals that have been bred to have no immune system!
We’ve published a bunch of data, both online and in scientific publications showing no increased cancer risk when using both same day and cultured stem cells to treat orthopedic problems. For example, our registry experience with more than 1,100 patients treated with same day stem cells showed no such risks. In addition, our data published in scientific journals on cultured stem cells also showed no increased cancer risks, even when patients were followed for many years. In fact, we voluntarily gave our source data to an independent European research group upon request and they concluded that our cultured stem cell procedure was safer than FDA approved knee gel injections.
Now a group of European scientists has published yet another long-term safety study, this time in the area of same day stem cell procedures used to treat orthopedic problems. A total of 1873 patients were treated from 1990 to 2006 with bone marrow-derived concentrated stem cells. Patients were monitored for cancer incidence from the date of the first operation (1990) until death, or until December 31, 2011. The mean follow-up time was 12.5 years (range, five to twenty-two years). The primary outcome was to evaluate the risk of tumors at the stem cell therapy treatment sites. The secondary outcome was to evaluate the risk of cancer diagnosed in areas other than the treatment sites. No tumor formation was found at the treatment sites on the 7306 MRIs and 52,430 x-rays obtained on the 1873 patients. Fifty-three cancers were diagnosed in areas other than the treatment site. On the basis of cancer incidence in the general population during the same period, the expected number of cancers would be between 97 and 108 for the same age and sex distribution (this group saw about half that many in treated patients). The conclusion? The study found no increased cancer risk over an average follow-up period of 12.5 years.
The upshot? This most recent study, as well as others, FDA clinical trials data, and the data we have published now amounts to about 10,000 patients who have been treated with adult stem cells and extensively tracked for this issue. There is no evidence that adult stem cells cause cancer. There is no rational reason for the fear, other than a completely different type of cell (ESC) that happens to have a similar name (stem cell) can cause teratomas – hence the confusion!