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Original Investigation
May 22, 2019

Incidence and Risk Factors of Keratinocyte Carcinoma After First Solid Organ Transplant in Ontario, Canada

Author Affiliations
  • 1Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
  • 2Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada
  • 3Department of Medicine, University of Toronto, Toronto, Ontario, Canada
  • 4Division of Nephrology, University Health Network, Toronto, Ontario, Canada
  • 5Division of Respirology, University Health Network, Toronto, Ontario, Canada
  • 6Li Ka Shing Knowledge Institute, St Michael's Hospital, Toronto, Ontario, Canada
  • 7Department of Surgery, St Michael's Hospital and University of Toronto, Toronto, Ontario, Canada
  • 8Women’s College Research Institute, Women’s College Hospital, Toronto, Ontario, Canada
  • 9Division of Dermatology, Women’s College Hospital, Toronto, Ontario, Canada
JAMA Dermatol. 2019;155(9):1041-1048. doi:10.1001/jamadermatol.2019.0692
Key Points

Question  What are the incidence and risk factors for posttransplant keratinocyte carcinoma in Canada?

Findings  This population-based cohort study of 10 198 transplant recipients in Ontario, Canada, found a 6.6-times increased risk of keratinocyte carcinoma in transplant recipients compared with the general population. The strongest risk factors for keratinocyte carcinoma were older age at transplant, white race, pretransplant invasive skin cancer, and posttransplant precancerous skin lesions.

Meaning  More frequent skin cancer screening, education, and early use of chemopreventive interventions may be warranted in the high-risk patient subsets identified by key risk factors.

Abstract

Importance  Keratinocyte carcinoma (KC), also known as nonmelanoma skin cancer, is the most common malignancy after solid organ transplant. Epidemiologic data on posttransplant KC in North America are limited by a lack of KC capture in cancer and transplant registries.

Objective  To estimate the incidence and identify risk factors for posttransplant KC.

Design, Setting, and Participants  This population-based inception cohort study in Ontario, Canada, used linked administrative databases and a health insurance claims–based algorithm. Participants were adult recipients of a first kidney, liver, heart, or lung transplant from January 1, 1994, to December 31, 2012. The cohort (n = 10 198) was followed up to December 31, 2013. Data were analyzed from May 31, 2016, to April 21, 2017.

Exposures  Solid organ transplant with functioning graft.

Main Outcomes and Measures  Age- and sex-adjusted standardized incidence ratio for KC in the transplant cohort was compared with that in the general population. Cumulative incidence of posttransplant KC was estimated using cumulative incidence functions, accounting for the competing risks of death or kidney graft loss. The association between KC and patient-, transplant-, and health services–related factors was evaluated with a multivariable cause-specific hazards model.

Results  A total of 10 198 transplant recipients were included in the study. The median (interquartile range [IQR]) age at transplant was 51 (41-59) years, with most recipients being male (6608 [64.8%]) and white (5964 [58.5%]). Posttransplant KC was diagnosed in 1690 patients (16.6%) after a median (IQR) of 3.96 (1.94-7.09) years, with an incidence rate of 2.63 per 100 patient-years (95% CI, 2.51-2.76). The rate of KC was significantly higher after transplant compared with the general population (standardized incidence ratio, 6.61; 95% CI, 6.31-6.93). The highest 10-year cumulative incidence was in the subsets of patients with a history of pretransplant skin cancer (66.5%), older than 50 years at transplant (27.5% for 51-65 years; 40.5% for >65 years), and of the white race (24.1%). The strongest independent risk factors for KC included older age at transplant (adjusted hazard ratio [aHR], 9.27; 95% CI, 7.08-12.14 for >65 years vs 18-35 years), white vs black race (aHR, 8.50; 95% CI, 4.03-17.91), pretransplant invasive skin cancer (aHR, 4.30; 95% CI, 3.72-4.98), and posttransplant precancerous skin lesions (aHR, 4.32; 95% CI, 3.77-4.95).

Conclusions and Relevance  The incidence of KC appeared to be substantially increased after transplant, particularly in patients who were older at transplant, were white, and had a history of cancerous or precancerous skin tumors; intensified skin cancer screening, education, and early use of chemopreventive interventions may be warranted for these high-risk patient subsets.

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