External Validation of the Skin and UV Neoplasia Transplant Risk Assessment Calculator (SUNTRAC) in a Large European Solid Organ Transplant Recipient Cohort

Abstract

ImportanceThe Skin and UV Neoplasia Transplant Risk Assessment Calculator (SUNTRAC) tool has been developed in the US to facilitate the identification of solid organ transplant recipients (SOTRs) at a higher risk of developing skin cancer. However, it has not yet been validated in populations other than the one used for its creation.ObjectiveTo provide an external validation of the SUNTRAC tool in different SOTR populations.Design, Setting, and ParticipantsThis retrospective external validation prognostic study used data from a prospectively collected cohort of European SOTRs from transplant centers at teaching hospitals in the Netherlands (1995-2016) and Spain (2011-2021). Participants were screened and followed up at dermatology departments. Data were analyzed from September to October 2021.Main Outcomes and MeasuresThe discrimination ability of the SUNTRAC tool was assessed via a competing risk survival analysis, cumulative incidence plots, and Wolbers concordance index. Calibration of the SUNTRAC tool was assessed through comparison of projected skin cancer incidences. Skin cancer diagnoses included squamous cell carcinoma, basal cell carcinoma, melanoma, and Merkel cell carcinoma.ResultsA total of 3421 SOTRs (median age at transplant, 53 [quartile 1: 42; quartile 3: 62] years; 2132 [62.3%] men) were assessed, including 72 Asian patients (2.1%), 137 Black patients (4.0%), 275 Latinx patients (8.0%), 109 Middle Eastern and North African patients (3.2%), and 2828 White patients (82.7%). With a total of 23 213 years of follow-up time, 603 patients developed skin cancer. The SUNTRAC tool classified patients into 4 groups with significantly different risks of developing skin cancer during follow-up. Overall, the relative rate for developing skin cancer estimated using subdistribution hazard ratios (SHRs) and using the low-risk group as the reference group, increased according to the proposed risk group (medium-risk group: SHR, 6.8 [95% CI, 3.8-12.1]; P < .001; high-risk group: SHR, 15.9 [95% CI, 8.9-28.4]; P < .001; very-high–risk group: SHR, 54.8 [95% CI, 29.1-102.9]; P < .001), with a concordance index of 0.72. Actual skin cancer incidences were similar to those predicted by the SUNTRAC tool (5-year skin cancer cumulative incidence for medium-risk group: predicted, 6.2%; observed, 7.0%).Conclusions and RelevanceThe findings of this external validation prognostic study support the use of the SUNTRAC tool in European populations for stratifying SOTRs based on their skin cancer risk and also detecting patients at a high risk of developing skin cancer. This can be helpful in prioritizing and providing better screening and surveillance for these patients.

Skin and UV Neoplasia Transplant Risk Assessment Calculator (SUNTRAC)—Keeping Solid Organ Transplant Recipients on Track for Skin Cancer Screening

“…Overall, the risk for developing skin cancer, compared with the low-risk group, increased with increasing risk group (medium risk: subdistribution hazard ratio [SHR], 6.8 [95% CI, 3.8-12]; P < .001; high risk: SHR, 15.9 [95% CI, 8.9-28]; P < .001; very high risk: SHR, 54.8 [95% CI, 29-103]; P < .001). The concordance index (C-index), at 5 years was 0.72 in the validation cohort, 6 which is comparable with the reported C-index in the SUNTRAC study of 0.74. 4 The C-index is a measure of a model's ability to correctly provide a reliable ranking of survival times based on individual risk scores.…”

“…A C -index of 0.5 indicates random chance, whereas a C -index of 1.0 indicates a perfectly corrected discrimination. Overall, these results provide external validation of the SUNTRAC tool for stratifying patients based on their skin cancer risk in different SOTR populations …”

“…Overall, these results provide external validation of the SUNTRAC tool for stratifying patients based on their skin cancer risk in different SOTR populations. 6 Strengths of the study by Gómez-Tomás et al 6 include the large sample size from 2 European countries. The Spanish cohort included significantly more White patients, which by default stratifies these patients into at least the mediumrisk group based on SUNTRAC scoring.…”

“…5 However, sensitivity analyses were performed in which BCC was not considered, and there were no major changes to their estimates or overall conclusions. 6 Another strength of the study by Gómez-Tomás et al 6 is the computation of time-dependent areas under the receiving operator characteristic curves (t-AUROCs) of the SUNTRAC tool at different time points over 8 years after transplant receipt, which demonstrated stable performance over time. The use of a time-dependent analysis is important, given the increasing incidence of skin cancer with longer follow-up periods after transplantation.…”

“…The study in this issue of JAMA Dermatology by Gómez-Tomás et al presents an external validation study of the SUNTRAC screening tool. This study included a prospectively collected cohort of SOTRs from academic transplant centers in the Netherlands and Spain.…”