Kidney transplant recipients died of keratinocyte cancer at 34 times the general rate

Design

Population-based cohort with linked registry data

Population

21 503 first kidney transplant recipients, Australia and New Zealand, 1990–2019

Primary outcome

Skin cancer mortality vs general population

Effect

SMR 11.1 overall; melanoma 4.5; keratinocyte cancer 34.5; 118.2 deaths per 100 000 person-years

This population cohort linked 21 503 first kidney transplant recipients in Australia and New Zealand (1990 to 2019) with national death registers, over 212 317 person-years.

There were 251 skin cancer deaths: 82 from melanoma and 169 from keratinocyte cancer. Skin cancer mortality was 118.2 per 100 000 person-years, 11.1 times that of the general population. The excess was 4.5-fold for melanoma and 34.5-fold for keratinocyte cancer. It was present in both sexes, all ages, every region and every decade, and highest in high-ultraviolet Queensland (SMR 14.8) and Western Australia (13.1).

The finding reframes keratinocyte cancer in transplant patients: not a minor nuisance but a substantial cause of death. Indian patients have darker skin types and lower absolute risk, but long-term immunosuppression still raises squamous cell carcinoma risk, and outdoor workers in high-UV regions are exposed. Scheduled skin review and fast access to excision are the tools.

• Offer every kidney transplant recipient a baseline skin examination and regular review, at least yearly.
• Fast-track excision of any new, growing or tender keratotic lesion in a transplant patient.
• Teach self-examination and daily sun protection, especially to outdoor workers.
• Tell the transplant team when multiple squamous cell carcinomas arise; immunosuppression may be modifiable.
• Do not dismiss a squamous cell carcinoma in a transplant patient as low risk.

Why it matters

Keratinocyte cancer, usually treated as low-stakes, was the main source of excess skin cancer death after transplant.

Don't overread it

The data come from a very high-UV, predominantly fair-skinned population; the size of the excess will be smaller in Indian patients.

The statistics, in plain English

A standardised mortality ratio of 34.5 means 34.5 times as many keratinocyte cancer deaths as expected in people of the same age and sex in the general population. Because deaths from keratinocyte cancer are very rare in the general population, a large ratio can still mean a modest absolute rate — here about 80 per 100 000 person-years.

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