A population-based study of skin cancer incidence and prevalence in renal transplant recipients.

BACKGROUND: Cancers occurring following solid organ transplantation are a rapidly growing public health concern. Defining the extent of the problem has been limited by surveillance systems with incomplete registration of cases and the paucity of reliable national incidence data.

OBJECTIVES: To determine the incidence of all cancers following renal transplantation and to make a detailed examination of trends and patterns associated with postrenal transplant skin cancers.

METHODS: Integration of data from the national renal transplant database and the national cancer registry in Ireland enabled accurate determination of the number of renal transplant recipients (RTRs) with skin cancers and other malignancies in the time period 1 January 1994 to 31 December 2001.

RESULTS: We demonstrated a biphasic increase in skin cancer incidence following renal transplantation, determined by the age at transplantation. There was a steady increase in risk for older RTRs (age 50+ years) from year 2 post-transplant, whereas the increased risk in younger RTRs (age < 50 years) occurred later but much more significantly, reaching 200 times the risk for an age-matched nontransplanted population by year 6 post-transplant. The number of nonmelanoma skin cancers (NMSCs) registered in RTRs accounted for 1% of all NMSCs registered nationally over the study period. The standardized incidence rates for invasive NMSC (33-fold increase) and in situ carcinoma of the skin (65-fold increase) were significantly increased (P < 0.05). The risk for invasive squamous cell carcinoma (SCC) was increased 82-fold compared with the nontransplanted population. Male RTRs were at particular risk of invasive SCC at sun-exposed sites such as the scalp and the external ear. Risk of malignant melanoma and Kaposi sarcoma were also increased relative to the nontransplanted population.

CONCLUSIONS: This comprehensive national study illustrates how rates of skin cancer in Irish RTRs have influenced the national incidence of skin cancer. The high incidence of SCC, basal cell carcinoma and Bowen's disease in the early post-transplant period for older patients and the cumulative risk in younger patients with increased duration of transplantation highlight the importance of implementing early and continued cancer surveillance regimens post-transplant.