Human leukocyte antigen type as a risk factor for nonmelanomatous skin cancer in patients after renal transplantation

Cutaneous squamous cell cancer (cSCC) risk and the human leukocyte antigen (HLA) system

Cutaneous squamous cell carcinoma (cSCC) is the second most common cancer among Caucasians in the United States, with rising incidence over the past decade. Treatment for non-melanoma skin cancer, including cSCC, in the United States was estimated to cost $4.8 billion in 2014. Thus, an understanding of cSCC pathogenesis could have important public health implications. Immune function impacts cSCC risk, given that cSCC incidence rates are substantially higher in patients with compromised immune systems. We report a systematic review of published associations between cSCC risk and the human leukocyte antigen (HLA) system. This review includes studies that analyze germline class I and class II HLA allelic variation as well as HLA cell-surface protein expression levels associated with cSCC risk. We propose biological mechanisms for these HLA-cSCC associations based on known mechanisms of HLA involvement in other diseases. The review suggests that immunity regulates the development of cSCC and that HLA-cSCC associations differ between immunocompetent and immunosuppressed patients. This difference may reflect the presence of viral co-factors that affect tumorigenesis in immunosuppressed patients. Finally, we highlight limitations in the literature on HLA-cSCC associations, and suggest directions for future research aimed at understanding, preventing and treating cSCC.

Association Between HLA Type and Skin Cancer in Kidney Transplant Recipients

BACKGROUND

Organ transplant recipients (OTRs) are more susceptible to various diseases, among them cancers. Nonmelanoma skin cancers (NMSC) represent the most common malignancies in OTRs in Europe. Due to the significantly higher morbidity, aggressive and rapid progression, and poor prognosis of NMSC in the OTR population, these patients require a special oncological approach. Intensive attention should therefore be paid to factors predisposing OTRs to the development of cancer. The aim of this study was to establish the role of genetic factors in the pathogenesis of skin cancer in kidney transplant recipients (KTRs).

METHODS

This single-center study was performed in 39 KTRs with posttransplant NMSC. The frequency of particular types of HLA Class I (HLA-A and HLA-B) and Class II (HLA-DR) in each group were compared to establish the association between the HLA type and risk of skin cancer after renal transplantation.

RESULTS

HLA-DR15 were more commonly detected in patients with MNSC than in the control group of KTRs (P = .014) There was also a positive correlation between HLA-B18 and skin squamous cell carcinoma. The antigen was more often recorded in KTRs with squamous cell carcinoma than in KTRs without NMSC (P = .03) and in the general population (P = .002).

CONCLUSIONS

Patients who are positive for HLA-BR15 and HLA-B18 should be under special dermatologic surveillance due to the potentially high risk of skin cancer.

Genetics and nonmelanoma skin cancer in kidney transplant recipients

Kidney transplant recipients (KTRs) have a 65- to 250-fold greater risk than the general population of developing nonmelanoma skin cancer. Immunosuppressive drugs combined with traditional risk factors such as UV radiation exposure are the main modifiable risk factors for skin cancer development in transplant recipients. Genetic variation affecting immunosuppressive drug pharmacokinetics and pharmacodynamics has been associated with other transplant complications and may contribute to differences in skin cancer rates between KTRs. Genetic polymorphisms in genes encoding the prednisolone receptor, GST enzyme, MC1R, MTHFR enzyme and COX-2 enzyme have been shown to increase the risk of nonmelanoma skin cancer in KTRs. Genetic association studies may improve our understanding of how genetic variation affects skin cancer risk and potentially guide immunosuppressive treatment and skin cancer screening in at risk individuals.

Post-transplantation malignancies: here today, gone tomorrow?

From the early days of transplantation onwards, increased cancer development in transplant recipients, who require immunosuppression to avoid graft rejection, has been recognized. Registry data indicate that approximately 10-30% of deaths are attributed to post-transplant malignancy, with an upward trend in this incidence as more patients have been exposed to chronic lifelong immunosuppression. In this Review, the overall incidence and most frequent types of cancer encountered are summarized, along with information about which transplant recipients are at the greatest risk of malignancy. Reasons for why differences exist in susceptibility to cancer in this patient population are examined, and approaches that might improve our understanding of the options available for reducing the incidence of this adverse effect of immunosuppression are described. Whether anti-rejection drugs have been successful in diminishing overall immunosuppressive burden, and consequently show any promise for decreasing post-transplant malignancies is also discussed. The topic shifts to one class of conventional anti-rejection drugs, the mammalian target of rapamycin (mTOR) inhibitors, which paradoxically have both immunosuppressive and anti-neoplastic properties. The complex activities of mTOR are reviewed in order to provide context for how these seemingly opposing effects are possible, and the latest clinical data on use of mTOR inhibitors in the clinic are discussed. The current and future perspectives on how best to normalize these unacceptably high rates of post-transplantation malignancies are highlighted.

Positivity for HLA DR1 is associated with basal cell carcinoma in renal transplant patients in southern Brazil

BACKGROUND

Renal transplant patients have a higher incidence of non-melanoma skin cancer (NMSC). Previous studies hypothesized that human leukocyte antigen (HLA), especially types DR1, DR4, and DR7, may influence the incidence of these tumors. This study investigates the association between NMSC and the presence of HLA DR1, DR4, and DR7 in renal transplant patients in southern Brazil.

METHODS

In a historical cohort study, 1032 patients who underwent renal transplantation during the period from January 1993 to December 2006 were examined to identify occurrences of NMSC and HLA status prior to transplant.

RESULTS

Of the 1032 patients examined, 59 (5.71%) developed NMSC (squamous cell carcinoma [SCC]: 2.42%; basal cell carcinoma [BCC]: 1.74%; both: 1.55%). The presence of HLA DR1 was associated with a higher probability of developing any NMSC and particularly with developing BCC (P < 0.05). There was no statistically significant association between the presence of HLA DR4 or DR7 and the occurrence of NMSC in this sample.

CONCLUSIONS

HLA DR1 appears to be associated with the development of BCC, as well as with the higher number of NMSC lesions in renal transplant patients. This study supports the trend to associate the DR1 allele with BCC and not with SCC.