The incidence of posttransplant malignancy among solid organ transplant recipients (SOTRs) is 10%; skin cancer, primarily nonmelanoma skin cancer (NMSC), constitutes 49.5% of all malignancies in this population.1 The etiology of the increased risk of cutaneous malignancy in SOTR is multifactorial:
The skin of SOTRs is photosensitive, compared to that of immunocompetent patients, thus predisposing SOTRs to carcinogenic damage resulting from exposure to UV light.2
Immunosuppression plays a key role in increasing the risk of cutaneous malignancy by inhibiting the ability of the immune system to recognize and destroy tumor cells.3
Human papillomavirus (HPV) can play a role in carcinogenesis by promoting molecular pathways to proliferation and survival of nascent tumor cells4;Times New Romanβ-HPV strains are disseminated ubiquitously in the skin of immunosuppressed patients.5
Some medications administered after transplantation can be directly carcinogenic.
NMSC in SOTRs also differs qualitatively from NMSC in immunocompetent patients. Cutaneous squamous cell carcinoma (cSCC) (FIGUREs 1 and 2) is the most common skin cancer among SOTRs, whereas basal cell carcinoma (BCC) is the most common skin cancer in the general population.3 cSCC in the SOTR population tends to be more aggressive, with more rapid local invasion and an increased rate of both in-transit and distant metastases, leading to an increase in morbidity and mortality. Mortality of metastatic cSCC among SOTRs is approximately 50%, compared to 20% in an otherwise healthy population.3,6-8
The problem is relevant to primary care
Screening. Because there is a demonstrated reduction in morbidity and mortality associated with early detection and treatment of NMSC, regular screening of skin is important in the SOTR population.9 A study in Ontario, Canada, from 1994 to 2012 and comprising 10,183 SOTRs, found that adherence to an annual skin check regimen for ≥ 75% of the observation period was associated with a 34% reduction in cutaneous BCC- and cSCC-related morbidity or death (adjusted hazard ratio = 0.66; 95% CI, 0.48-0.92).10 Although routine follow-up with a dermatologist is recommended for SOTRs,9,11-15 only 2.1% of patients in the Canadian study were fully adherent with annual skin examination, and 55% never visited a dermatologist.10 Consequently, primary care physicians can play a key role in skin cancer screening for SOTRs.
Education regarding the importance of protection from the sun is also an essential part of primary care. A 2018 study of SOTRs in Turkey demonstrated that16
46% expressed a lack of knowledge of the hazards of sun exposure
44% did not recall ever receiving medical advice regarding sun protection
89% did not wear sun-protective clothing
86% did not use sunscreen daily.
Multiple studies have demonstrated the positive effect that preventive education and attendance at a dermatology or skin cancer screening clinic can have on sun-protective behaviors among SOTRs.9,16-18 In the Turkish study, 100% of patients who reported using sunscreen daily had been undergoing regular dermatologic examination.16
In this article, we review current management guidelines regarding the prevention and treatment of NMSC in SOTRs.
Recommendations for prevention
Screening skin exams (TABLE 11,11,12,15,19-23). Although definitive guidelines do not exist regarding the frequency of a screening skin exam for SOTRs, multiple frequency-determining algorithms have been proposed.11,12,15,19 The recommended frequency of a skin exam is based on history of skin cancer; for SOTRs, the most common recommendation19 is a full-body skin examination as follows:
annually—when there is no history of skin cancer
every 6 months—when there is a history of actinic keratoses (AKs; precancerous lesions that carry a risk of transforming into cSCC) or a single low-risk NMSC
every 3 months—when there is a history of multiple NMSCs or a single high-risk NMSC
every 1 to 3 months—when there is a history of metastatic disease.