"We've always known that certain tumors are increased after transplantation. Certain tumors are known to be related to viruses, so when we give immunosuppressant drugs, we're decreasing the body's ability to fight off viruses," explained Dr. Lewis Teperman, chief of transplant surgery at NYU Langone Medical Center in New York City.
Not all of the cancers can be linked to immunosuppression, however. In some cases, especially with liver and lung cancers, it's possible that a tiny cancer was present in the body before transplant.
"It's hard to sort out the exact cause of cancer, but some are clearly related to being immunosuppressed," Granger said.
Engels' study reviewed data from nearly 176,000 solid organ transplants done between 1987 and 2008.
The investigators found the overall incidence of cancer was 2.1 times higher than would be expected in a non-transplant population.
The risk of non-Hodgkin lymphoma was increased more than sevenfold. The rates of lung and liver cancer were also significantly increased, but Engels said this may be due to previous cancers. For example, a treatment for some liver cancers is a liver transplant, and it's possible that some cancer cells may survive the transplant process. The risk of lung cancer was highest in those who received a lung transplant, and the risk of liver cancer appeared to be elevated only in those who received a liver transplant.
The incidence of kidney cancer was increased in all transplant recipients by almost five times, according to the study. The researchers said this might be due to the underlying disease process in people who need new kidneys, and that the immunosuppressants likely play a role for all transp
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