Risk of lip cancer after solid organ transplantation in the United States

Solid organ transplant recipients have an increased risk of lip cancer, but the reasons are uncertain. Using data from the Transplant Cancer Match Study, we describe the epidemiology of lip cancer among 261,500 transplant recipients in the United States. Two-hundred thirty-one lip cancers were identified, corresponding to elevated risks for both invasive and in situ lip cancers (standardized incidence ratios of 15.3 and 26.2, respectively). Invasive lip cancer incidence was associated with male sex (adjusted incidence rate ratio [aIRR] 2.01, 95%CI 1.44–2.82), transplanted organ (0.33, 0.20–0.57, for liver transplants and 3.07, 1.96–4.81, for lung transplants, compared with kidney transplants), and racial/ethnic groups other than non-Hispanic whites (0.09, 0.04–0.20). In addition, incidence increased with age and during the first three years following transplant, and was higher in recipients prescribed cyclosporine/azathioprine maintenance therapy (aIRR 1.79, 95%CI 1.09–2.93, compared with use of tacrolimus/mycophenolate mofetil) and following a diagnosis of cutaneous squamous cell carcinoma (4.21, 2.69–0.94). The elevation in lip cancer incidence is consistent with an effect of immunosuppression. Notably, the very strong associations with white race and history of prior skin cancer point to an important role for ultraviolet radiation exposure, and cyclosporine and azathioprine may contribute as photosensitizing or DNA damaging agents.