Do skin cancer rates differ by transplanted organ type and patient age?
Dr. Schwarzenberger is the physician editor of DermWorld. She interviews the author of a recent study each month.
By Kathryn Schwarzenberger, MD, FAAD, March 1, 2023
In this month’s Clinical Applications column, Physician Editor Kathryn Schwarzenberger, MD, FAAD, talks with Lee Wheless, MD, PhD, FAAD, about his JAMA Dermatology paper, ‘Differences in skin cancer rates by transplanted organ type and patient age after organ transplant in white patients.’
DermWorld: You and your colleagues recently published a study looking at skin cancers in organ transplant patients. Can you tell us briefly about your study and your key findings?
Dr. Wheless: We conducted a retrospective electronic health record-based cohort study examining the timing of the development of multiple skin cancers in solid organ transplant recipients. For the development of the first skin cancer, we replicated the well-established pattern of thoracic organ recipients having a higher risk than liver recipients, but for the second and third skin cancers there was no difference based on transplanted organ type. Instead, age at transplant was a far better predictor of skin cancer development across all organ types.
DermWorld: What prompted this study?
Dr. Wheless: In residency we all learn that heart and lung recipients have the highest skin cancer risk, but in my transplant clinic I was seeing that many of my patients with innumerable skin cancers had neither of these. I realized that most of the studies to date had looked at only the first skin cancer and not what happens after that. Skin cancer is unlike other cancers where generally a patient will develop a single cancer, become a “case,” and that is their cancer status. We know that a patient with a single superficial BCC is going to have a dramatic prognosis in terms of morbidity and mortality compared to someone who is developing new SCCs every month, but there really have been no good data to study these different phenotypes. Half of all skin cancer deaths among solid organ transplant recipients come from a minority with 10 or more skin cancers, so it’s important we can identify these patients sooner when prevention might be more effective.
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DermWorld: Did you get the results you were expecting to find?
Dr. Wheless: Yes and no. Our results for the first skin cancer replicated the findings from multiple cohorts showing heart and lung recipients with the shortest time to development, and liver recipients with the longest. This was reassuring that our data were valid. What was unexpected was that when we accounted for mortality, the risk for subsequent cancer development no longer differed by organ type, and age at transplant was far more important. This seems obvious but it’s very important to put into clinical practice and not a one-size-fits-all protocol for following transplant recipients.
DermWorld: You limited your study to skin cancers in white patients. Was this just a reflection of the numbers involved? Do we have good data on the incidence of skin cancer rates in Black organ transplant recipients?
Dr. Wheless: This was due to numbers. Fortunately, skin cancer among patients with skin types V and VI remains rare even after transplant in the U.S. In the UK we see much higher rates of Kaposi sarcoma that we really aren’t seeing at least in Tennessee. A few years back, Christina Chung did a great study looking at non-white transplant recipients and saw that skin cancers were present in <6% of patients, and that many of these were not related to sun exposure, but rather with HPV infection.
DermWorld: Obviously, transplant recipients are on immunosuppressive medications. Were you able to look for potential impact of different immunosuppressive regimens in this study?
Dr. Wheless: I’m convinced the choice of immunosuppressant is playing a central role in the elevated skin cancer risk, through both immunologic and non-immunologic effects. Unfortunately, the data are pretty messy and couldn’t be included in this study, but it is a question I am actively pursuing. Cyclosporine and azathioprine do appear to convey greater risks than other immunosuppressants, while mTOR inhibitors and potentially belatacept seem to have lower skin cancer risk. We love topical tacrolimus in dermatology, but when given systemically it has a very low volume of distribution to the skin and we see lower risks compared to cyclosporine despite a very similar mechanism of action.
DermWorld: Do you anticipate that the results of this study will impact the management of our patients with organ transplants?
Dr. Wheless: I think it gives us more liberty to space out follow-ups for those younger transplant recipients. It also really threw out any notion that liver recipients are always “low risk” for skin cancer. As we have seen in countless studies in the general population, anyone with one skin cancer can be considered “high risk” for developing more. I hope these results will encourage us to look beyond simple case/control status and collect more granular data in our studies that include not only timing and number of skin cancers, but also type and subtype so we can continue to refine and personalize skin cancer care.
Dr. Wheless is assistant professor at Vanderbilt University Medical Center. His paper appeared in JAMA Dermatology.
This work was supported by grants from the Skin Cancer Foundation and the Dermatology Foundation. Dr. Wheless is currently funded by VA CSR&D IK2-CX002452.
Disclaimer: The views and opinions expressed in this article do not necessarily reflect those of DermWorld.