Organ transplant recipients are at increased risk of a wide range of malignancies, especially cutaneous squamous cell carcinomas (SCC). Few previous population-based studies have quantified and compared cancer risks according to graft type and with long-term follow-up. Using nationwide Swedish registers, we identified 10,476 recipients transplanted from 1970 to 2008 and followed them for cancer occurrence. Relative risks of cancer in comparison with the general population were expressed as standardized incidence ratios (SIR) and within the transplanted cohort as incidence rate ratios (IRR). During a total follow-up of 93,432 person-years, patients were diagnosed with 1,175 cancers excluding SCC, and with 2,231 SCC, SIR cancer excl SCC 2.4 (95% CI, 2.2-2.5); SIR SCC 121 (95% CI, 116-127). Cancer risks were most increased among heart and/or lung recipients SIR cancer excl SCC 3.3 (95% CI, 2.8-4.0); SIR SCC 198 (95% CI, 174-224), followed by kidney SIR cancer excl SCC 2.3 (95% CI, 2.1-2.4); SIR SCC 121 (95% CI, 116-127) and liver recipients SIR cancer excl SCC 2.3 (95% CI, 1.9-2.8); SIR SCC 32 (95% CI, 24-42). During follow-up, risk of cancer excluding SCC remained stable while risk of SCC tripled over 20 years irrespective of graft type, partly due to a subgroup of patients developing new SCCs at a rapidly increasing rate. In summary, posttransplant cancer risk varied by transplanted organ and by cancer site, with the bulk of the excess risk driven by an exceptionally high and accelerating risk of SCC. These findings underscore the importance of regular skin screening in organ transplant recipients.

Risk of BCC was strikingly elevated in OTRs compared with the general population. Risk was higher in kidney recipients and increased with follow-up time. These findings support a tumour-promoting effect of immunosuppressive drugs in BCC development. The low SCC to BCC ratio was possibly attributed to short follow-up time.

Development of malignant tumours in chronic burn wounds or scars is extremely rare, but a frequently reported complication. Most of these tumours are squamous cell carcinoma and, more occasionally, basal cell carcinoma and malignant melanoma are reported. The interval between the initial burn and the diagnosis of the tumour is usually long; 20-30 years or more. A large number of case reports and small series of selected patients have been published. Only one epidemiological study has been performed recently, but it could not confirm any increased risk. We conducted a historical cohort study to assess the risk of cancer in Swedish patients with burn injuries. Using the national Inpatient Registry we identified 37,095 patients who had been hospitalized for burn injuries. This cohort was linked with the Swedish Cancer Registry for a virtually complete follow-up with regard to cancer. The mean follow-up time was 16.4 years (range >0-39). The risk of developing any form of cancer was slightly increased: standardized incidence ratio (SIR) 1.11 (95% confidence interval (CI) 1.06-1.16) based on 2227 patients with cancer. However, squamous cell carcinoma: SIR 0.88 (95% CI 0.70-1.09) and malignant melanoma: SIR 0.88 (95% CI 0.68-1.12) did not occur more often than expected. Also, in a subgroup of 12,783 patients who were followed for 20-39 years, no increased risk of skin cancer could be detected. This study does not support any casual association between burn injuries and a later risk of skin cancer.

No abstract