Cancer is twice as likely to develop in people who have received an organ transplant than in people who have not, according to new research.
The study led by Dr Eric Engels from the National Cancer Institute in Rockville, Maryland, is based on data about 175,732 transplants. It found that more than 10,000 patients developed cancer in the years after surgery.
The findings, published in the Journal of the American Medical Association, suggest that the increased risk applies regardless of which organ the patients had received. It also applies to several forms of cancer, as tumours often develop in the new organ.
The risk of developing liver cancer was 500 times higher for liver patients in the six months after surgery than for other members of the population, the study found. In the following 10 to 15 years, it was still twice as high.
The researchers said the increased risk could be due to a reduced immune resistance to viruses that trigger the deadly disease. Underlying medical conditions, inflammation or drug toxicity were also cited as contributing factors.