Transplant patients are twice as likely to develop melanoma as people who don’t receive a donor organ, and three times more likely to die of the dangerous skin cancer, new research shows.
The findings suggest that immunosuppressive drugs used to keep patients from rejecting new organs—especially the high doses at the time of transplant—may make them more susceptible to later stage cancers that are harder to cure.
Transplant recipients were four times more likely to be diagnosed with regional stage melanoma, which has already begun to spread to other parts of the body.
“We knew that melanoma was more likely in transplant recipients, but we thought it might be a function of intensive screening since they are very likely to develop less deadly forms of skin cancer and are checked regularly by dermatologists,” says study leader Hilary A. Robbins, an epidemiology graduate student at the Johns Hopkins University Bloomberg School of Public Health.
“To the contrary,” Robbins says, “we were surprised to see that transplant recipients were particularly at risk for developing melanomas that weren’t found until they had already spread.”
The researchers, who report their work in the Journal of Investigative Dermatology, were also surprised to see an elevated risk of aggressive melanomas especially in the first four years after transplant. Transplant patients must take immunosuppressant medications for the rest of their lives to prevent organ rejection.
Transplant patients with melanoma
In 2011, there were more than 65,000 cases of melanoma in the United States, according to the Centers for Disease Control and Prevention. Melanoma can spread to other parts of the body and causes over 9,000 US deaths every year, making it the deadliest form of skin cancer. It is most commonly linked to exposure to the ultraviolet rays given off by the sun.
Some types of cancer are more common among immune-suppressed people, such as those infected with HIV and transplant recipients. But Robbins says these are typically cancers that are linked to viruses like cervical cancer, Kaposi’s sarcoma, and lymphoma. Melanoma is not linked to a virus.
Robbins, who conducted much of the research while working at the National Cancer Institute, and colleagues studied 139,991 non-Hispanic white transplant recipients in the Transplant Cancer Match Study at NCI. The study links data on all transplants in the US to 15 population-based cancer registries, and includes information on almost half of the country’s transplant population between 1987 and 2010. The researchers found 519 melanomas in this group and analyzed risk factors for developing melanoma.
With a different data set, the researchers compared outcomes among 182 melanoma patients in the transplant group with more than 130,000 other people with melanoma. Over 15 years, 27 percent of the transplant recipients died of their melanoma, as compared to 12 percent of the non-recipients.
The researchers discovered that melanoma patients who had received a transplant were three times more likely to die from their melanoma, even for melanomas that were diagnosed at an early stage or were very small.
The researchers found that the late-stage cases of melanoma were associated with use of medication given at the time of transplant that essentially stops T-cells—the main cells of immune response—from functioning in order to keep them from attacking the new organ.
Meanwhile, early melanomas were more likely to be found in recipients who were administered a medication called azathioprine, a maintenance drug given long-term to some transplant recipients. This drug is known to multiply the effects of ultraviolet radiation, which could lead to the development of melanoma.
Robbins says her group’s findings suggest that transplant candidates should be screened very carefully for skin cancers before receiving their organs. She also says that closer monitoring after transplant could allow melanoma to be detected earlier, preventing patients from developing deadly metastatic cancer.
Many researchers are working to develop transplant protocols that reduce or even eliminate the need for lifelong immunosuppressive medications, as these make organ recipients more likely to develop other medical problems.
The research received partial support from the Intramural Research Program of the National Cancer Institute.
Source: Johns Hopkins University