The researchers suggest that no one who has had melanoma should ever be an organ donor.
Transfer of cancer from a donated organ to a transplant patient is rare, and the chances of it occurring long after the donor was treated were thought to be extremely unlikely. The longest known interval in a donor-related melanoma was eight years between surgery and transplant.
But in Thursday's New England Journal of Medicine, researchers said two patients got cancer from a donor who had a melanoma skin lesion removed 16 years earlier and was thought to be cancer-free.
Melanoma cells had apparently been dormant in the donor's kidneys until the transplant, explained Dr. Rona M. MacKie, who treated the recipients. The cancer cells flourished because medicines given to the patients to prevent rejection of the transplants had suppressed their disease-fighting immune systems.
"Anyone who's had invasive melanoma should not be a transplant donor in the future," said MacKie of Glasgow University.
The U.S. transplant network also strongly recommends against using organs from donors with a history of melanoma or a number of other cancers, according to Dr. H. Myron Kauffman, director of the United Network for Organ Sharing's transplant tumor registry.
Of the 125,000 transplants done in the United States between 1994 and 2001, there were only 24 cases of donor-related cancer, he said. Ten of the patients died, including four who developed melanoma from a single donor's organs.
"It happens but it's extremely rare," he said.
Surgeons sometimes have to weigh the risks of using an organ from a former cancer patient with the urgent need for a life-saving organ, Kauffman said.
"That's the balancing act that surgeons have to go through," he said.
In the Scottish case, the 47-year-old donor died in 1998 of what was thought to be a brain hemorrhage. Her relatives didn't mention her bout with melanoma when they agreed to donate her kidneys. Now, MacKie said, the donor's primary physician is asked about their medical history.
The kidneys were given to a man and a woman, both in their 50s. A year and a half later, the woman was diagnosed with melanoma and died. A few months later, the man was also discovered to have melanoma.
MacKie checked the identity of their anonymous donor and confirmed her suspicions: The transplants came from a single donor with a a history of melanoma. She said she was "appalled that 16 years after a not-too-bad melanoma, this had happened."
The male patient's cancer was confined to his kidney. He was taken off anti-rejection drugs, given medicine to boost his immune system and his transplanted kidney removed. He is now on dialysis and doing well, MacKie said.
By Stephanie Nano