Skin cancer mortality in Australian and New Zealand kidney transplant recipients: a population-based cohort study using linked health data, 1990–2019

Overview

Background

Transplant recipients have an increased risk of skin cancer and related death compared with the general population. How demographics or geography impact on mortality is unclear. Understanding these will help identify groups at highest risk of skin cancer death.

Objectives

To estimate skin cancer mortality rates among kidney transplant recipients in Australia and New Zealand and describe excess mortality by demographics and geography, relative to the general population, and change over time.

Methods

We linked kidney transplant recipients from the Australia and New Zealand Dialysis and Transplant Registry with National Death Registers in Australia and New Zealand from 1990 to 2019. We identified deaths from melanoma (International Classification of Diseases 10th Revision code C43), keratinocyte cancer (KC; C44) and carcinoma in situ (D04), and estimated absolute mortality per 100 000 person-years of follow-up (PY). We used indirect standardization to estimate standardized mortality ratios (SMRs) with 95% confidence intervals (CIs) for kidney transplant recipients compared with the general population by sex, age at death, decade of death, and New Zealand or Australian state.

Results

We included 21 503 individuals who received their first kidney transplant between 1990 and 2019. There were 251 deaths from skin cancer, 82 from melanoma and 169 from KC, over 212 317 PY of follow-up. The absolute skin cancer mortality rate was 118.2 per 100 000 PY (95% CI 104.1–134.2), 38.6 per 100 000 PY for melanoma (95% CI 31.1–48.0) and 79.6 per 100 000 PY for KC (95% CI 68.5–92.6). Skin cancer mortality was 11.1 times higher in kidney transplant recipients compared with the general population (SMR) overall, 4.5 times higher for melanoma and 34.5 times higher for KC. Excess skin cancer mortality relative to the general population was observed in both sexes, across all age groups, residential areas and decades of follow-up. Excess mortality was highest in regions with high ultraviolet radiation (UVR) indices – the Australian states of Queensland (SMR 14.8, 95% CI 11.7–18.8) and Western Australia (SMR 13.1, 95% CI 8.7–19.7), and in New Zealand (SMR 11.0, 95% CI 8.3–14.6).

Conclusions

Kidney transplant recipients are at increased risk of skin cancer death, especially from KC, in all demographics and regions in Australia and New Zealand, especially those with high UVR indices. Enhanced surveillance and rapid treatment entry are warranted.