People who receive a kidney transplant are nearly four times more likely to develop melanoma, a rare but deadly form of skin cancer, according to a study in the November 1, 2005 issue of Cancer, a peer-reviewed journal of the American Cancer Society.
The study indicates that risk increased with time since transplant. Furthermore, risk was highest in men - and with increasing age in men - but was significantly lower in women and blacks.
Of the various types of skin cancer, melanoma is the deadliest, with a mortality rate up to 6 percent in some regions of the world. The classic risk factors for melanoma are ultraviolet radiation, commonly caused by sunburns, a suppressed immune system, and family history of abnormal moles. Studies demonstrate that the immune system plays a critical role in monitoring the body for - and destroying - early cancerous cells, including melanoma.
Patients taking immunosuppressants after organ transplantation would be assumed to be at higher risk for cancers. Studies show that this holds true for nonmelanoma skin cancers but do not agree for melanoma risk. The baseline low incidence of melanoma in the general population may contribute to conflicting data. Low incidence of disease means that more people need to be studied to discern an association.
In the largest study to date, Christopher S. Hollenbeak, Ph.D., of Penn State College of Medicine and his colleagues compared melanoma incidence rates from a registry of renal transplant patients (89,786 patients) to general population data.
They found that renal transplant recipients are 3.6 times more likely to develop melanoma than the general population. Risk increases five percent per year after the transplant. Though some melanomas will develop immediately after transplant, risk continues to increase approximately five percent per year from transplant. Melanoma risk is greatest in men and increases rapidly with age. In contrast, while women are at increased risk, too, their risk is significantly lower than men and does not increase with age. Comparison by race shows that blacks are seven-times less likely to develop melanoma than other races.
"Kidney transplant patients, who are receiving long-term immunosuppression," conclude the Dr. Hollenbeak and his colleagues, "have a 3.6-fold increase in the incidence of melanoma when compared to the general population" and should receive regular complete skin examinations.