Some transplanted kidneys carry sinister stowaways that trigger cancer in the people whose lives they have just saved. The cancer is called Kaposi鈥檚 sarcoma and can be fatal if not properly treated.
The stowaways include a herpes virus known to cause Kaposi鈥檚 sarcoma, as well as cells infected with the virus that have already turned cancerous.
The discovery strengthens the case for donated organs to be screened more thoroughly. At present, organs in many countries are routinely screened for obvious tumours, for HIV and for the viruses that cause hepatitis B and C. None is screened for human herpesvirus-8 (HHV-8), which causes Kaposi鈥檚 sarcoma.
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However, it might be possible to kill or control the virus in the recipient. This could be done either with antiviral drugs or with white blood cells from the donor, as these are already primed to combat the virus.
Suppressed immunity
Kaposi鈥檚 sarcoma is one of the most common cancers linked with transplants, occurring in one in every 200 kidney recipients in the US. This frequency is 400 to 500 times higher than the rate in the general population.
This increased risk is probably due to the drugs transplant patients take to suppress their immune systems and avoid rejection of their new organ. This may allow HHV-8 to flourish and cause tumours. Kaposi鈥檚 sarcoma is also common in people suffering from AIDS.
HHV-8 has been noticed before in kidney recipients who later developed Kaposi sarcoma, but the new study is the first to show that virus-laden cells can come with the transplant.
Mario Luppi, of the University of Modena and Reggio Emilia in Modena, Italy, and colleagues analysed cancerous skin cells from six women with Kaposi sarcoma. The women had previously received new kidneys from men. In tissue from five of the women, they found cancerous male cells infected with the virus, which are likely to have come from the transplant.
Missing link
The work provides 鈥渞easonable鈥� evidence for the link, says Patrick Moore, of the University of Pittsburgh Cancer Institute, Pennsylvania, in a commentary accompanying the Nature Medicine paper.
Between 20 and 50 per cent of patients who receive an infected organ develop Kaposi鈥檚 sarcoma, Moore notes. This 鈥渉ighlights the need to perform HHV-8 testing in the transplant setting鈥�, he says.
Chris Rudge, the medical director of UK Transplant, says that Kaposi鈥檚 sarcoma in a donated organ would be a 鈥渃ontra-indication鈥� to transplant, but cautions that there is no routine test for the virus.
鈥淚n the UK, we鈥檝e reviewed the whole process of pre-donation patient screening in great detail,鈥� he says. 鈥淲e believe we have one of the most thorough systems possible.鈥�
