It is well documented that solid organ transplant recipients (OTRs) are at greater risk of developing skin cancer following transplant surgery. However, a new study conducted by Harvard Medical School researchers found that an immunosuppressive drug lowers the risk of subsequent skin cancer following an initial posttransplant cancer diagnosis. The findings lead researchers to say a low-dose of sirolimus may prove beneficial for patients who develop multiple or high risk skin cancers following a solid organ transplant. "In this mixed-organ cohort of OTRs, patients taking sirolimus after developing posttransplant skin cancer had a lower risk of developing subsequent skin cancer with no increased risk for overall mortality," the researchers wrote. "Gradual conversion to a low-dose [mammalian target of rapamycin]-based regimen may be considered in patients who develop multiple or high-risk skin cancers to decrease their skin cancer burden. Further studies are needed to define optimal conversion regimens and dosing in such scenarios." Sirolimus is an immunosuppressive drug used in combination with other medications to prevent rejection of kidney transplants. Prior studies indicated a relationship between lower rates of skin cancer in OTRs who were treated with sirolimus. "However, little information exists on the use of sirolimus for the prevention of skin cancer in nonrenal OTRs or those already diagnosed as having a posttransplant cancer," the study's authors wrote. The study was published in the Jan. 20, 2016 issue of JAMA Dermatology. In the retrospective cohort study, researchers reviewed medical records of OTRs diagnosed with posttransplant cancer between the years 2000 and 2008. The research team identified which organ was transplanted, whether the patients had pretransplant and/or post transplant cancers and any immunosuppressive medications the patients took. Patients were treated at Brigham and Women's Hospital and Massachusetts General Hospital. The team looked at 329 solid organ transplant recipients who developed any type of cancer following transplant surgery. The majority were men with a mean age of 56 years. Of the OTRs: 17.6 percent received a heart transplant, 53.8 percent received a kidney transplant, 16.4 percent received a lung transplant, 10.3 percent received a liver transplant, 1.8 percent received a mixed-organ transplant. Overall, nearly 40 percent of study participants were diagnosed with a second post-transplant cancer. The majority of diagnosed malignancies (88.5 percent) were skin cancers. Of the OTRs included in the study, nearly 30 percent (97 patients) underwent sirolimus therapy after the initial cancer diagnosis. Among the patients who received sirolimus, there was an 11.6 percent reduction in the risk of developing a secondary skin cancer following the initial cancer diagnosis. In the group that received sirolimus, 26.8 percent of patients developed a secondary skin cancer compared with 38.4 percent who did develop skin cancer in the group that did not receive the drug. "Conversion to sirolimus therapy may be considered in OTRs who develop cancer if the risk for skin cancer is of concern," the authors wrote in the study's conclusion. "Larger studies are needed to quantify sirolimus-associated risk reduction for other cancer types."