HLA antigen frequencies in renal transplant recipients and non-immunosuppressed patients with non-melanoma skin cancer

Recent Research Trends against Skin Carcinoma - An Overview

Skin cancer is a prevalent and sometimes lethal cancer that affects a wide range of people. UV radiation exposure is the main cause of skin cancer. Immunosuppression, environmental factors, and genetic predisposition are other contributing variables. Fair-skinned people and those with a history of sunburns or severe sun exposure are more likely to experience this condition. Melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) are the three main forms. Melanoma poses a bigger hazard because of its tendency for metastasis, while SCC and BCC have limited metastatic potential. Genetic mutations and changes to signalling pathways such as p53 and MAPK are involved in pathogenesis. Early diagnosis is essential, and molecular testing, biopsy, dermoscopy, and visual inspection can all help. In addition to natural medicines like curcumin and green tea polyphenols, treatment options include immunotherapy, targeted therapy, radiation, surgery, and chemotherapy. Reducing the incidence of skin cancer requires preventive actions, including sun protection and early detection programs. An overview of skin cancers, including their forms, pathophysiology, diagnosis, and treatment, highlighting herbal therapy, is given in this review.

The Immunogenetics of Non-melanoma Skin Cancer

Non-melanoma skin cancer (NMSC) is the most common malignancy seen in Caucasians and includes basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The incidence of NMSC is showing an increasing trend which is attributed to the increased use of sunbeds, recreational sun exposure, aging population, and partly to improved screening and reporting. Ultraviolet (UV) radiation plays the most crucial role in the pathogenesis of both BCC and SCC by inducing DNA damage and mutagenic photoproducts. Other risk factors are fair skin, old age, genetic predisposition, immunosuppression, ionizing radiation, organic chemicals, and HPV infection. The role of genomic instability, genetic mutations/aberrations, and host immunity has been fairly illustrated in several studies. This chapter aims to discuss these aspects of NMSC in detail.

Case Report: Combined Intra-Lesional IL-2 and Topical Imiquimod Safely and Effectively Clears Multi-Focal, High Grade Cutaneous Squamous Cell Cancer in a Combined Liver and Kidney Transplant Patient

Cutaneous squamous cell carcinoma (cSCC) is the second most common non-melanoma skin cancer worldwide, with ever increasing incidence and mortality. While most patients can be treated successfully with surgical excision, cryotherapy, or radiation therapy, there exist a subset of patients with aggressive cSCC who lack adequate therapies. Among these patients are solid organ transplant recipients who due to their immunosuppression, develop cSCC at a dramatically increased rate compared to the normal population. The enhanced ability of the tumor to effectively undergo immune escape in these patients leads to more aggressive tumors with a propensity to recur and metastasize. Herein, we present a case of aggressive, multi-focal cSCC in a double organ transplant recipient to frame our discussion and current understanding of the immunobiology of cSCC. We consider factors that contribute to the significantly increased incidence of cSCC in the context of immunosuppression in this patient population. Finally, we briefly review current literature describing experience with localized therapies for cSCC and present a strong argument and rationale for consideration of an IL-2 based intra-lesional treatment strategy for cSCC, particularly in this immunosuppressed patient population.

Association between Human Leukocyte Antigen Type and Keratinocyte Carcinoma Risk in Renal Transplant Recipients

Keratinocyte carcinoma (KC), defined as squamous cell carcinoma and basal cell carcinoma, is the most common malignancy among white, non-Hispanic renal transplant recipients. Although recent genome-wide association studies reported that class II HLA is associated with KC risk, epidemiologic data on HLA type and KC risk in renal transplant recipients is limited. Using an institutional cohort of white, non-Hispanic renal transplant recipients transplanted between 1993 and 2017, we examined the association between pretransplant molecular HLA types and KC risk. Posttransplant KCs were captured using the International Classification of Diseases codes and validated using pathology reports. Cox proportional hazards regression models were used to estimate hazard ratios of incident KC, squamous cell carcinoma, and basal cell carcinoma, adjusting for age, male sex, history of KC, Charlson comorbidity index, HLA mismatch, transplant type, year of transplant, and the type of immunosuppression. Among 617 subjects (mean age 53 years, 67% male), 10% developed posttransplant KC. Multivariable Cox regression analyses showed HLA-DRB1∗13 was associated with KC risk (hazard ratio, 1.84; 95% confidence interval, 1.00-3.38) and squamous cell carcinoma risk (hazard ratio, 2.24; 95% confidence interval, 1.12-4.49), whereas HLA-DRB1∗14 (hazard ratio, 2.81; 95% confidence interval, 1.14-6.91) was associated with basal cell carcinoma risk. Our findings suggest that a subset of renal transplant recipients with specific HLA polymorphisms may be at increased KC risk.

HLA alleles in renal transplant recipients with nonmelanoma skin cancer in southeastern Brazil

BACKGROUND

Renal transplant recipients are submitted to immunosuppression to avoid graft rejection, which makes them susceptible to various conditions. Furthermore, these individuals present malignant tumors more frequently than the general population, including nonmelanoma skin cancer. The individual genetic basis that acts in the pathogenesis of cutaneous cancer may present a protection or susceptibility factor for disease development. One of these factors is the HLA complex.

OBJECTIVE

To investigate HLA alleles association to the occurrence of nonmelanoma skin cancer in renal transplant recipients from São Paulo State.

METHODS

A total of 213 patients (93 renal transplant recipients with nonmelanoma skin cancer and 120 renal transplant recipients without nonmelanoma skin cancer) were evaluated by retrospective and cross-sectional study. Epidemiological, clinical and HLA typing data were found in databases. HLA class I (A, B) and class II (DR) alleles were compared to establish their association with nonmelanoma skin cancer.

RESULTS

Comparing renal transplant recipients with and without nonmelanoma skin cancer, the HLA-B*13 allele was associated with higher risk of developing nonmelanoma skin cancer while B*45 and B*50 alleles were associated with protection.

STUDY LIMITATIONS

The HLA A, B and DR alleles identification for the kidney transplantation routine is done by low and medium resolution techniques that do not allow discrimination of specific alleles.

CONCLUSION

The involvement of HLA alleles in nonmelanoma skin cancer in renal transplant recipients was confirmed in this study. Renal transplant recipients with HLA-B*13 showed higher risk for developing a skin cancer (OR= 7.29) and should be monitored for a long period of time after transplantation.

Keratinocyte Carcinomas: Current Concepts and Future Research Priorities

Cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC) are keratinocyte carcinomas, the most frequently diagnosed cancers in fair-skinned populations. Ultraviolet radiation (UVR) is the main driving carcinogen for these tumors, but immunosuppression, pigmentary factors, and aging are also risk factors. Scientific discoveries have improved the understanding of the role of human papillomaviruses (HPV) in cSCC as well as the skin microbiome and a compromised immune system in the development of both cSCC and BCC. Genomic analyses have uncovered genetic risk variants, high-risk susceptibility genes, and somatic events that underlie common pathways important in keratinocyte carcinoma tumorigenesis and tumor characteristics that have enabled development of prediction models for early identification of high-risk individuals. Advances in chemoprevention in high-risk individuals and progress in targeted and immune-based treatment approaches have the potential to decrease the morbidity and mortality associated with these tumors. As the incidence and prevalence of keratinocyte carcinoma continue to increase, strategies for prevention, including effective sun-protective behavior, educational interventions, and reduction of tanning bed access and usage, are essential. Gaps in our knowledge requiring additional research to reduce the high morbidity and costs associated with keratinocyte carcinoma include better understanding of factors leading to more aggressive tumors, the roles of microbiome and HPV infection, prediction of response to therapies including immune checkpoint blockade, and how to tailor both prevention and treatment to individual risk factors and needs.

Genetic variants in the HLA class II region associated with risk of cutaneous squamous cell carcinoma

BACKGROUND

The immune system has been implicated in the pathophysiology of cutaneous squamous cell carcinoma (cSCC) as evidenced by the substantially increased risk of cSCC in immunosuppressed individuals. Associations between cSCC risk and single nucleotide polymorphisms (SNPs) in the HLA region have been identified by genome-wide association studies (GWAS). The translation of the associated HLA SNPs to structural amino acids changes in HLA molecules has not been previously elucidated.

METHODS

Using data from a GWAS that included 7238 cSCC cases and 56,961 controls of non-Hispanic white ancestry, we imputed classical alleles and corresponding amino acid changes in HLA genes. Logistic regression models were used to examine associations between cSCC risk and genotyped or imputed SNPs, classical HLA alleles, and amino acid changes.

RESULTS

Among the genotyped SNPs, cSCC risk was associated with rs28535317 (OR = 1.20, p = 9.88 × 10^- 11) corresponding to an amino-acid change from phenylalanine to leucine at codon 26 of HLA-DRB1 (OR = 1.17, p = 2.48 × 10^- 10). An additional independent association was observed for a threonine to isoleucine change at codon 107 of HLA-DQA1 (OR = 1.14, p = 2.34 × 10^- 9). Among the classical HLA alleles, cSCC was associated with DRB1*01 (OR = 1.18, p = 5.86 × 10^- 10). Conditional analyses revealed additional independent cSCC associations with DQA1*05:01 and DQA1*05:05. Extended haplotype analysis was used to complement the imputed haplotypes, which identified three extended haplotypes in the HLA-DR and HLA-DQ regions.

CONCLUSIONS

Associations with specific HLA-DR and -DQ alleles are likely to explain previously observed GWAS signals in the HLA region associated with cSCC risk.

Incidence of nonmelanoma skin cancer in renal transplant recipients: A systematic review and meta-analysis

Background

Nonmelanoma skin cancer (NMSC) in renal transplant recipients is common and associated with significant morbidity and mortality. The aim of the present systematic review and meta-analysis was to estimate the incidence of NMSC among renal transplant recipients.

Materials and Methods

We systematically searched PubMed, Medline, Scopus, and Web of Science databases for studies that assessed the incidence of NMSC in renal transplant recipients using a combination of relevant keywords. Two independent investigators included studies and extracted necessary information. Random effect meta-analysis was used to estimate pooled incidence of NMSC with 95% confidence intervals (CIs).

Results

Twenty-nine studies comprising 36,021 patients meet the criteria for the systematic review. The pooled incidence of NMSC in renal transplant recipients was 12.6% (95% CI: 12%-14%) with a majority of squamous cell carcinoma (SCC) 55% (95% CI: 47%-63%). The pooled estimate of the incidence rates of SCC and basal cell carcinoma was 2.7% (95% CI: 2%-3.4%) and 2.2% (95% CI: 1.5%-2.8%), respectively. Subgroup analysis per geographic location showed that pooled incidence of NMSC was 39.1% (95% CI: 26.3%-51.8%), 12.4% (95% CI: 8.8%-16%), and 1.2% (95% CI: 0.4%-2%) in Australia and New Zealand, Europe, and Middle East, respectively.

Conclusion

The results of the current meta-analysis demonstrated that the incidence of NMSC in renal transplant recipients varies widely. Regarding the high incidence of NMSC among renal transplant recipients, awareness of associated risk factors and early diagnosis of the malignancy in the population is a major clinical need.

Non Melanoma Skin Cancer Pathogenesis Overview

(1) Background: Non-melanoma skin cancer is the most frequently diagnosed cancer in humans. The process of skin carcinogenesis is still not fully understood. However, several studies have been conducted to better explain the mechanisms that lead to malignancy; (2) Methods: We reviewed the more recent literature about the pathogenesis of non-melanoma skin cancer focusing on basal cell carcinomas, squamous cell carcinoma and actinic keratosis; (3) Results: Several papers reported genetic and molecular alterations leading to non-melanoma skin cancer. Plenty of risk factors are involved in non-melanoma skin cancer pathogenesis, including genetic and molecular alterations, immunosuppression, and ultraviolet radiation; (4) Conclusion: Although skin carcinogenesis is still not fully understood, several papers demonstrated that genetic and molecular alterations are involved in this process. In addition, plenty of non-melanoma skin cancer risk factors are now known, allowing for an effective prevention of non-melanoma skin cancer development. Compared to other papers on the same topic, our review focused on molecular and genetic factors and analyzed in detail several factors involved in non-melanoma skin cancer.

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.

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.

The development of squamous cell carcinoma in a patient after kidney transplantation: a case report

In patients with organ transplantation as compared to the general population the risk of cancer is significantly increased. The most common changes are malignant tumors of the skin, constituting 30-65% of malignant tumors found in recipients. Potential risk factors for skin cancer after a transplant operation are: solar radiation, immunosuppressive therapy, genetic factors, infection with HPV and skin cancer transmission before transplantation. In contrast to the immunocompetent population, skin cancers in transplant recipients are dominated by squamous cell carcinoma, followed by basal cell carcinoma. Squamous cell carcinoma in patients after transplantation is characterized by a strong tendency to give local recurrences and distant metastases. Due to the high risk of developing skin cancer in transplant recipients, preventive oncology plays an important role in the long-term care of patients after transplantation. This includes: sun protection, education, and early treatment of patients with precancerous lesions. It is also stressed that systematic dermatologic studies need to be carried out in patients after transplantation surgery. The paper contains basic information about skin cancers in organ transplant recipients: epidemiology, potential risk factors, treatment and prognosis. The paper presents also a case of patient who developed squamous cell carcinoma of the skin 3 years after renal transplantation.

Nonmelanoma skin cancer in solid organ transplant recipients: update on epidemiology, risk factors, and management

BACKGROUND

Nonmelanoma skin cancers (NMSC) are the most frequently observed cancers in solid organ transplant recipients (SOTR) and may have a significant disease burden.

OBJECTIVE

To provide an update regarding the epidemiology and management of NMSC in SOTR.

RESULTS

Ten-year incidence rates range from 10% in Italy to 20% in Northern Europe to 70% in Australia. More than 50% of NMSC are located on sun-exposed areas (head, dorsum of hands). Many risk factors have been identified, including age at transplantation, fair skin, type of immunosuppressive drugs, cumulative sun exposure, viral infections, and various genetic markers. Patients with a first NMSC have a 49 times higher risk of developing a subsequent NMSC. Skin self-examination and photoprotection should be encouraged in all transplanted patients. Long-term skin surveillance, early diagnosis and aggressive treatment of any suspicious lesion, reduction of immunosuppressive therapy, and conversion to m-TOR inhibitors can be also effective measures for reduction of NMSC incidence.

CONCLUSIONS

NMSC is the most frequent cancer observed in SOTR. Early diagnosis, patient education, and modification of immunosuppression are effective measures for reduction of NMSC incidence.

HLA and skin cancer

Skin cancer - melanoma and non melanoma - are common neoplasm with rising incidence over the last decades. It is an important public health problem. Its pathogenesis is not completely understood and the same happens with the genetic factors involved. The genes that encode the HLA are associated with some tumors and they may be responsible for one of the mechanisms that take part in the development of the before mentioned cancers. We have reviewed the literature on the subject of HLA antigens, melanoma and non melanoma skin cancer.

Multigenic control of skin tumour development in mice

Different inbred mouse strains vary greatly in their susceptibility to tumour development in a variety of tissues. Intraspecific and interspecific crosses can, therefore, be used to map the loci that control this predisposition. Crosses of Mus musculus with Mus spretus are highly resistant to tumour development in the skin, liver, lung and lymphoid system. M. spretus, therefore, has dominantly acting resistance loci, which we have attempted to map. More than 350 interspecific backcross mice were followed for 18 months to assess susceptibility to development of chemically induced papillomas and carcinomas. The results were analysed using a combination of MAPMAKER/QTL analysis and multiple regression analysis for the determination of linkage in multigenic quantitative traits. The results showed clearly that at least three genes on chromosomes 5 and 7 control resistance to tumour development. Importantly, some genes confer resistance to benign tumours but they have relatively little effect on malignant progression. This suggests the existence of different classes of benign tumours: those that are capable of tumour progression and those that have only a very low probability of becoming malignant. Identification of these genes will improve our understanding of mechanisms of carcinogenesis and may provide a novel route to the identification of "low-penetrance' human tumour susceptibility genes.

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

Renal-transplant recipients are at an increased risk for developing nonmelanomatous skin cancer (NMSC). Recipient human leukocyte antigen (HLA) type has been suggested as a possible risk factor. We studied the association between HLA type and posttransplant NMSC in 2,433 renal-transplant recipients in a Northern climate, for whom HLA type and clinical follow-up were available. One hundred six (4.3%) patients developed NMSC between 1984 and 1997. Of previously reported HLA-associated risk factors, only HLA A11 showed an increased incidence of posttransplant skin cancer, at 8% (P=0.0137, odds ratio 2.03 with 95% confidence interval 1.11-3.53) in 1998. This effect persisted at follow-up, in a limited reanalysis in 2004. HLA A11 may be a useful marker, in some populations, for identifying at the time of transplantation those patients that are at an increased risk for NMSC and who may therefore be good candidates for preventative clinical trials.

Comparative Epidemiology and Pathogenic Factors for Nonmelanoma Skin Cancer in Organ Transplant Patients

BACKGROUND

Organ transplantation has been performed for almost 40 years with steadily increasing success regarding long-time survival of the graft as well as quality of life for the patient. An increase of skin cancers as a consequence of the lowered cellular immune response seems to parallel the overall increased survival rate of organ transplant recipients. Against the background of chronic immunosuppression, known risk factors like the amount of sun exposure before and after transplantation and oncogenic viruses as well as the genetic background and place of residence (latitude) are strongly related with the increased skin cancer incidence. The goal of this review is to compare the epidemiologic prevalence of nonmelanoma skin cancer between various geographic locations and to highlight pathogenesis factors.

METHODS

This study was based on a review of the current literature.

RESULTS

The increasing incidence of nonmelanoma skin cancer paralleling a prolonged survival of patients after organ transplantation represents a significant reason for morbidity and long-term mortality in organ transplant recipients worldwide. The incidence of nonmelanoma skin cancer in liver, kidney, and heart transplant recipients varies from 1.5% to 22%, 2% to 24%, and 6% to 34%, respectively, within 5 years of transplantation depending on geographic location and other pathogenesis factors. Ultraviolet radiation (UVR) as well as immunosuppressant therapy are crucial risk factors regarding the induction and progression of skin cancer. UVR is related to the induction of DNA damage as well as interference with Langerhans cell antigen presentation and a TH1-TH2 shift induced via release of IL-10. Whereas the overall duration of immunosuppression and the accumulative dosage applied are relevant measures in the pathogenesis of an increased tumor risk, individual differences between specific immunosuppressive agents are more difficult to assess.

CONCLUSIONS

Multiple international studies assess risk factors and pathophysiology of skin cancer in organ transplant patients, with variable results in the literature. Large multicenter studies with thorough multivariant analysis may provide useful information for center-independent analysis of pathogenesis factors for transplant-related skin cancer.

Localization of a non-melanoma skin cancer susceptibility region within the major histocompatibility complex by association analysis using microsatellite markers

The major histocompatibility complex (MHC) is known to have a role in the development of non-melanoma skin cancer (NMSC), although the genes and mechanisms involved have yet to be determined. To identify the susceptibility locus for NMSC within the MHC, we used a collection of well-defined polymorphic microsatellite markers from the Human leucocyte antigen (HLA) region for an association analysis of 150 cases with NMSC and 200 healthy controls selected from the Busselton population in Western Australia. High-resolution mapping was undertaken using a total of 40 highly polymorphic markers located at regular intervals across the HLA region (3.6Mb). Polymerase chain reaction (PCR) analysis was initially performed on pooled DNA markers to detect those markers that showed different allele profiles. Statistically significant differences in allelic frequencies (differentiating alleles) were found between cases and controls at three polymorphic microsatellite loci within a 470-kb genomic susceptibility region ranging between 6 kb centromeric of the HLA-B gene and intron 5 of the DDR gene. Interestingly, this genome region corresponded completely with the psoriasis-susceptibility locus. The three differentiating alleles and another four markers outside the susceptibility region were then PCR tested by individual genotyping of cases and controls. The newly identified susceptibility locus for NMSC within the MHC was found to be significantly different between the cases and controls by comparisons of allele frequencies at the three differentiating loci estimated from DNA pools and then confirmed by individual genotyping. This is the first study using high density microsatellite markers to localize a NMSC susceptibility region within the human genome.

Skin cancer in kidney and heart transplant recipients and different long-term immunosuppressive therapy regimens

BACKGROUND

Nonmelanoma skin cancer occurs frequently in organ transplant recipients, but the relative importance of different immunosuppressive therapy regimens is unclear.

OBJECTIVE

We studied the risk of skin cancer in the complete, single-center Norwegian cohort of kidney and heart transplant recipients (n = 2561).

METHODS

We determined cancer risk estimation by means of standardized incidence ratios and multivariate Cox regression.

RESULTS

Transplant recipients had an increased risk of cutaneous squamous cell carcinoma (SCC) (65-fold), malignant melanoma (3-fold), and Kaposi's sarcoma (84-fold), and of lip SCC (20-fold), compared with the general population. After adjustment for age, kidney transplant recipients receiving cyclosporine, azathioprine, and prednisolone had a significantly (2.8 times) higher risk of cutaneous SCC relative to those receiving azathioprine and prednisolone. After adjustment for age and type of immunosuppressive regimen, heart transplant recipients had a significantly (2.9 times) higher risk than kidney transplant recipients.

CONCLUSION

The risk of cutaneous SCC, malignant melanoma, Kaposi's sarcoma, and lip SCC is increased in kidney and heart transplant recipients. The risk of posttransplant cutaneous SCC is related to the degree of immunosuppression caused by long-term immunosuppressive therapy.

Skin cancer in Australian heart transplant recipients

BACKGROUND

Cutaneous malignancy is a major cause of morbidity in organ transplant recipients.

OBJECTIVE

Our purpose was to report on skin cancer in Australian heart transplant recipients with analysis of HLA factors.

METHODS

We reviewed histologically proven skin cancers in the first 455 patients undergoing organ transplantation in Sydney, Australia.

RESULTS

The cumulative incidence of skin cancer was 31% at 5 years and 43% at 10 years with a squamous cell carcinoma/basal cell carcinoma ratio of 3:1. Caucasian origin, increasing age at transplantation, and duration of follow-up were significantly associated with skin cancer. Skin cancer accounted for 27% of 41 deaths occurring after the fourth year. Recipient HLA-DR homozygosity was associated with skin cancer overall, whereas HLA-DR7 was a protective factor in skin cancer overall, squamous cell carcinoma, and Bowen's disease. HLA-A1 and HLA-A11 were significant protective factors in Bowen's disease.

CONCLUSION

Skin cancer is a major cause of morbidity and long-term mortality in heart transplant patients.

Celtic ancestry, HLA phenotype and increased risk of skin cancer

Individuals of Celtic ancestry are claimed to be at greater risk of skin cancer than non-Celts, and various positive and negative associations between certain human leucocyte antigen (HLA) phenotypes and the development of skin cancer have been described. The aims of this study were to determine whether any HLA phenotypes are associated either with Celtic or non-Celtic ancestry, or skin type. One thousand and ten members of the Welsh Bone Marrow Donor Registry (WBMDR), whose HLA phenotypes are known, were asked to complete a questionnaire which enquired as to their family origins and their 'Index of Celtic Ancestry' scored out of 12. Three groups were identified: non-Celts (score < 3), Celts (score > 9), and a subset of the Celts--'high scoring' Celts (score > 10). Details of hair and eye colour and skin type were also requested. Skin type and HLA-A, -B, -DR and -DQ frequencies were compared between the three groups (Celts, non-Celts and 'high scoring' Celts), and a random indigenous population of 9196 members of the WBMDR. Seven hundred and thirty-six replies were received (279 male, 457 female, mean age 31 years). One hundred and forty-four Celts, 51 'high scoring' Celts and 170 non-Celts were identified. Forty-six (32%) Celts had skin type I or II compared with 36 (21%) non-Celts (P = 0.039), and 37 (73%) 'high scoring' Celts had skin type I or II (P < 0.0001). However, there were no significant differences between the groups with regard to hair colour, eye colour or number of episodes of painful sunburn. The frequency of HLA-DR4 was 32% in the non-Celtic group, 44% in the Celtic group (not significant), and 53% in the 'high scoring' Celts (P = 0.008). However, the difference was not significant after correction. There were no significant associations between skin type and HLA phenotype. HLA-DR4 is known to be associated with an increased risk of both basal cell carcinoma and malignant melanoma and its increased frequency in Celts may be an independent risk factor for skin cancer in addition to skin type.

Relation between HLA antigens and skin cancer in renal transplant recipients in Queensland, Australia

On the basis of previous studies that showed a negative association between HLA-A11 and skin cancer in renal transplant recipients and a positive association with HLA-B27 and HLA-DR7, we performed a study in Queensland with 1098 recipients to address the question of whether the same associations could be found. The influence of HLA mismatching and HLA homozygosity on the risk of skin cancer was also studied. In contrast to earlier studies, HLA-A11 was associated with an increased risk of skin cancer. On the other hand, we confirmed that the HLA-B27 antigen was associated with the development of skin cancer, but only when the development of basal cell carcinomas alone was considered, and we confirmed that there is a weak but not statistically significant association with HLA-DR7. No association between HLA mismatching or HLA homozygosity and the development of skin cancer was observed. Environmental factors such as different levels of exposure to sunlight and infection with human papillomaviruses are factors that are most likely to be involved. We hypothesize that human papillomavirus-induced antigens prevail in the skin cancers in the recipients living in the Netherlands, whereas antigens induced by solar radiation, the so-called "photo-antigens," may be more common in the skin cancers of the recipients living in Queensland. Exposure to sunlight can also induce immunologic unresponsiveness, and excessive exposure to sunlight in Australia may, therefore, simply override the risk factors that are important in countries with a more temperate climate.

Cutaneous malignancies in renal transplant recipients from Nova Scotia, Canada

Four hundred and seventy-four Nova Scotian renal transplant recipients were screened, using the records of the Nova Scotia Cancer Registry and the Victoria General Hospital, in a retrospective study, for the development of cutaneous malignancies. Sixteen patients developed a total of 60 squamous cell carcinomas (SCC) and 14 developed 28 basal cell carcinomas (BCC). The survival curve shows that within 10 years of transplant, less than 10% will develop SCC. This is a 16-fold increase above the rate of SCC in the general population of Nova Scotia, Canada. Age at time of transplantation appears to be a significant determinant of subsequent skin cancer risk. None of the previously reported HLA associations was found to hold in this small study. The role of ultraviolet radiation, due to both geographic and lifestyle exposure, is discussed when comparing to other transplant studies.

Skin cancer and warts in immunosuppressed renal transplant recipients

Non-melanoma skin cancer (NMSC) is increasingly recognised as a complication of long-term immunosuppression and has been particularly studied in renal transplant recipients (RTR). A population study of renal transplant recipients has been performed with analysis of those features contributing to a high rate of detection of NMSC, such that 40% patients with fair skin have NMSC 5 years after transplantation. 90% of the total patient population have warts 5 years after transplantation, many being atypical and in sun-exposed sites. Therefore, contributory factors in these patients include not only the global immunosuppression, ultraviolet radiation (UVR)-induced mutagenesis and photoimmunosuppression, but also the widespread presence of human papillomavirus (HPV) infection, including the unusual epidermodysplasia verruciformis (EV)-associated cutaneous oncogenic HPV.