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

Actinic keratosis. Current treatment options

Actinic keratoses are hyperkeratotic skin lesions that represent focal abnormal proliferation of epidermal keratinocytes. Some actinic keratoses evolve into squamous cell carcinoma of the skin, while others resolve spontaneously. The conversion rate of actinic keratosis to squamous cell carcinoma is not accurately known, but appears to be in the range of 0.25 to 1% per year. Although there is a low rate of conversion of actinic keratoses to squamous cell carcinoma, 60% of squamous cell carcinomas of the skin probably arise from actinic keratoses. The main cause of actinic keratoses in otherwise healthy Caucasians appears to be the sun. Therapy for actinic keratoses begins with prevention which starts with sun avoidance and physical protection. Sunprotection with sunscreens actually slows the return of actinic keratoses in patients already getting actinic keratoses. Interestingly, a few studies are available that demonstrate that a high fat diet is associated with the production of more actinic keratoses than is a low fat diet. One of the mainstays of therapy has been local destruction of the actinic keratoses with cryotherapy, and curettage and electrodesiccation. A new addition to this group of therapies to treat individual actinic keratoses is photodynamic therapy with topical aminolevulinic acid and light. In patients who have numerous actinic keratoses in an area of severely sun damaged skin, therapies which are applied to the whole actinic keratosis area are used. The goal of treating such an area of skin is to treat all of the early as well as the numerous clinically evident actinic keratoses at the same time. The classical approaches for treating areas of photodamaged skin without treating actinic keratoses individually include: the use of topically applied fluorouracil cream, dermabrasion, and cutaneous peels with various agents like trichloroacetic acid. Both topically as well as orally administered retinoids have been used to treat actinic keratoses but retinoids alone are probably not an optimal monotherapy. Photodynamic therapy with topical aminolevulinic acid and light is a new therapy for actinic keratoses. Aminolevulinic acid is a precursor of protoporphyrin IX (PpIX) which is synthesized in the actinic keratosis when it is treated with aminolevulinic acid, and the PpIX photosensitizes the actinic keratosis so that light exposure can lead to its destruction. Photodynamic therapy with topical aminolevulinic acid is approved in the US to treat multiple individual actinic keratoses on the face and scalp and has similar cure rates to those reported for cryotherapy and fluorouracil therapy.

Skin cancer in heart transplant recipients: frequency and risk factor analysis

BACKGROUND

The frequency of skin cancer is increased among organ transplant recipients, but the predisposing risk factors are controversial. It is also unclear whether heart transplant patients face an increased risk compared to recipients of other organs, e.g. kidney transplants.

METHODS

We performed univariate and multivariate analysis of risk factors for skin cancer in 252 heart transplants and in a control series of 228 kidney transplants followed up at a single center. An extensive dermatologic examination was carried out; baseline features, type of immunosuppression, number of 3A rejection episodes, extent of sunlight exposure and skin type were recorded. Multivariate analysis (Cox regression) included: age at transplantation, sex, skin type (Fitzpatrick's criteria), presence of solar keratosis, presence of warts, type of organ, sunlight exposure.

RESULTS

During follow up skin cancer was more common among heart transplants (40, 16 %) than in kidney transplants (16, 7%, p = 0.004). The cumulative incidence of skin cancer by life table analysis increased from 16% after 5 years to 33% after 10 years in heart transplant patients and from 6% to 17% in kidney transplants (p 10000 hours (relative risk = 2.8), but not organ type were significant risk factors.

CONCLUSION

Age at transplant, skin type and sunlight exposure, but not type of organ and type of immunosuppressive regimen, are associated with increased risk of skin cancer in heart transplantation.

Epidemiology of actinic keratoses and squamous cell carcinoma

OBJECTIVE

The purpose of this article was to review the frequency, distribution, and determinants of actinic keratoses (AKs) and squamous cell carcinoma (SCC).

METHODS

A review of the literature was done.

RESULTS

AKs are extremely common lesions on the sun-exposed skin of Caucasian persons. The most important risk factors are a combination of genetic propensity ("fair skin phenotype") and cumulative sun exposure. Their prevalence increases with advancing age. The epidemiology of SCC is virtually the same, but the lesions occur most often on the head rather than on the upper extremities where most AKs are located. AKs are the most important risk factor identifying those most predisposed to the development of an SCC.

CONCLUSION

AKs are a reliable marker for those people most predisposed to development of an invasive SCC. In addition, AKs are probably an early stage in a biologic continuum that culminates in SCC. However, there are many more AKs than SCCs, and it is difficult to predict exactly which lesions will progress to invasive cancer.

Differences in sialyl-Tn antigen expression between keratoacanthomas and cutaneous squamous cell carcinomas

Keratoacanthoma and squamous cell carcinoma are common skin tumors, especially in immunosuppressed transplant recipients, but the distinction between these two types of epidermal neoplasia may be difficult. Sialyl-Tn (Sia-GalNAc-O-Ser/Thr) is a cell surface carbohydrate associated with hyperplasia in squamous epithelium, and correlated with poor prognosis in several human adenocarcinomas. Twenty-seven keratoacanthomas and 29 cutaneous squamous cell carcinomas were examined for the expression of sialyl-Tn and of the Ki67 epitope, the latter a marker for cell proliferation. By immunohistochemistry, basaloid tumor cells at the periphery of tumor nests showed some degree of sialyl-Tn expression in 16 keratoacanthomas (59%), while only three squamous cell carcinomas (10%) showed sialyl-Tn-positive basaloid tumor cells (p<0.001). Keratinized, differentiated tumor cells were more often sialyl-Tn-positive in keratoacanthomas (89%) than in squamous cell carcinomas (31%) (p<0.001). A striking sialyl-Tn-positivity in the basal cell layer was found in a border zone directly adjacent to most tumors of both types (88 and 88%). By immunohistochemical examination of parallel sections and by double immunofluorescence, sialyl-Tn antigen expression was primarily seen in cells that did not express Ki67, although some overlap was present. Keratoacanthomas from transplant recipients did not differ in sialyl-Tn expression compared to those from non-immunosuppressed patients. The results indicate that sialyl-Tn expression is not directly related to cell proliferation, but rather to cellular features of post-mitotic cells, and that sialyl-Tn is not associated with a malignant phenotype. Sialyl-Tn may be linked to tumor regression, as seen in keratoacanthomas.