Cancer in organ transplant recipients

Abstract

Tens of thousands of transplantations are performed around the world each year. Organ transplant recipients (OTR) are obliged to receive life-long medical treatment with immunosuppressive drugs to ensure graft function. However, such medications entail an increased risk of developing a broad spectrum of malignancies, especially skin cancer. This thesis aims to study cancer in OTRs from different aspects such as cancer incidence, survival, risk factors and prevention. Also, differentiation of squamous cell carcinoma (SCC) among OTRs.

Study I: The aim of this study was to investigate the degree of differentiation of SCC in OTRs compared to immunocompetent individuals. The degree of differentiation refers to how cancer cells look and function compared to normal cells. Data from the Swedish Cancer Registry (SCR) were cross-checked with data from the Transplant Registry (TR). Only patients with a diagnosis (SCC, Basosquamous Carcinoma and/or SCC in situ) from the Department of Dermatology, SUH, between 2002-2010 were included. The control group consisted of those who were diagnosed with the same diagnosis at the same time period at SUH as OTRs. No significant differences were observed in the degree of tumour differentiation in SCCs appearing in OTRs compared to those in the control group (p=0.4). In conclusion: SCCs in OTRs do not seem to be more aggressive than in the general population.

Study II: The aim of this study was to investigate whether specialized OTR clinics with dermatological follow-up, as has been suggested, provide additional benefit. In this descriptive study, in total, 696 OTRs and non-organ transplant patients (non-TPs) completed a sun exposure questionnaire between 2011 and 2015. The control group, the non-TPs, were recruited among outpatients at the Department of Dermatology SUH. We also compared OTRs with dermatological follow-up to OTRs with no follow-up. Fewer OTRs than non-TPs had experienced ≥1 sunburn in the past year (20% vs 46% p<.0001). There were more frequent users of sunscreen among OTRs with follow-up than among other OTRs (63% vs 44%, p=0.006). More OTRs with follow-up used ≥1 sun protection measure (covering clothes etc.) than other OTRs (54% vs 34%, p=0.016). Thus, OTRs reported less sun exposure compared to non-TPs, consolidating the positive effect of sun protection advice following transplantation. Today, post-transplant sun protection advice is standard.

Study III. The aim of this study was to investigate cancer incidence and survival in 664 patients who underwent heart transplantation (HTx) at SUH between 1985-2017. Data was retrieved from SCR and the Cause of Death Registry. The median follow-up time was 7.7 years. We found in total 279 malignancies in 90 patients. Of all patients, 19% had experienced malignancy after almost seven years after HTx. We found an overall risk of cancer to be over 6.2-fold higher than the general population and 2.9-fold higher when excluding non-melanoma skin cancer (NMSC).

Study IV. The aim of this study was to investigate cancer incidence and survival in 614 patients who underwent lung transplantation (LTx) at SUH between 1990-2016. Data was retrieved from SCR and the Cause of Death Registry. The median follow-up time was 5.1 years. We found 159 malignancies in 111 patients which corresponds to 18% of the total study population. We found an overall risk of cancer to be 5.56-fold higher than the general population and 2.76-fold higher when excluding NMSC.