Azathioprine and Risk of Skin Cancer in Organ Transplant Recipients: Systematic Review and Meta-Analysis

Area of Science:

• Immunology
• Dermatology
• Oncology

Background:

• Azathioprine is an immunosuppressant that can photosensitize skin.
• Previous studies on azathioprine and skin cancer risk in organ transplant recipients (OTRs) have yielded inconsistent results.
• Azathioprine's potential to increase reactive oxygen species raises concerns about carcinogenicity.

Purpose of the Study:

• To systematically review and pool risk estimates regarding azathioprine's association with skin cancers.
• To evaluate the specific risks of squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and keratinocyte cancers (KCs) in OTRs on azathioprine.
• To clarify the carcinogenicity of azathioprine in the context of organ transplantation.

Main Methods:

• Systematic literature review of studies investigating azathioprine and skin cancer risk.
• Meta-analysis of risk estimates from 13 eligible studies.
• Quantitative analysis of SCC, BCC, and KC risk associated with azathioprine treatment.

Main Results:

• A significantly increased risk of SCC was observed with azathioprine exposure (RR 1.56, 95% CI 1.11-2.18).
• No significant association was found between azathioprine and BCC risk (RR 0.96, 95% CI 0.66-1.40).
• No significant association was found between azathioprine and overall KC risk (RR 0.84, 95% CI 0.59-1.21).
• Significant heterogeneity was noted across studies for all outcomes.

Conclusions:

• Pooled evidence supports that azathioprine treatment increases the risk of SCC in OTRs.
• Azathioprine does not appear to significantly increase the risk of BCC or other KCs in this population.
• Further research may be needed to address heterogeneity and confirm findings.