Ultraviolet radiation as a cause of skin tumors

The 2018 World Health Organization Classification of Cutaneous, Mucosal, and Uveal Melanoma: Detailed Analysis of 9 Distinct Subtypes Defined by Their Evolutionary Pathway

CONTEXT.—

There have been major advances in the understanding of melanoma since the last revision of the World Health Organization (WHO) classification in 2006.

OBJECTIVE.—

To discuss development of the 9 distinct types of melanoma and distinguishing them by their epidemiology, clinical and histologic morphology, and genomic characteristics. Each melanoma subtype is placed at the end of an evolutionary pathway that is rooted in its respective precursor, wherever appropriate and feasible, based on currently known data. Each precursor has a variable risk of progression culminating in its fully evolved, invasive melanoma.

DATA SOURCES.—

This review is based on the "Melanocytic Tumours" section of the 4th edition of the WHO Classification of Skin Tumours, published in 2018.

CONCLUSIONS.—

Melanomas were divided into those etiologically related to sun exposure and those that are not, as determined by their mutational signatures, anatomic site, and epidemiology. Melanomas on the sun-exposed skin were further divided by the histopathologic degree of cumulative solar damage (CSD) of the surrounding skin, into low and high CSD, on the basis of degree of associated solar elastosis. Low-CSD melanomas include superficial spreading melanomas and high-CSD melanomas incorporate lentigo maligna and desmoplastic melanomas. The "nonsolar" category includes acral melanomas, some melanomas in congenital nevi, melanomas in blue nevi, Spitz melanomas, mucosal melanomas, and uveal melanomas. The general term melanocytoma is proposed to encompass "intermediate" tumors that have an increased (though still low) probability of disease progression to melanoma.

A missense mutation in damage-specific DNA binding protein 2 is a genetic risk factor for ocular squamous cell carcinoma in Belgian horses

BACKGROUND

Belgian horses are commonly affected with ocular squamous cell carcinoma (SCC), the most common cancer of the equine eye. A missense mutation in damage-specific DNA binding protein 2 (DDB2 c.1013C>T, p.Thr338Met) has been established as a recessive genetic risk factor for ocular SCC in the Haflinger breed. A sample of Belgian horses with unknown SCC phenotype was shown to possess this variant at a similar frequency to the Haflinger breed. Retrospective studies indicate that chestnut coat colour may predispose to the development of SCC.

OBJECTIVES

To determine if DDB2 c.1013C>T is a risk factor for ocular SCC in a strictly phenotyped sample of Belgian horses. To investigate associations between coat colour loci genotypes and ocular SCC.

STUDY DESIGN

Retrospective and prospective case identification, genetic investigation.

METHODS

Genomic DNA was isolated from blood, hair or formalin-fixed paraffin-embedded tissue from 25 Belgian horses with histologically confirmed ocular SCC and 18 unaffected Belgian horses. Association testing of 34 single nucleotide variants from 11 genomic loci and genotyping for DDB2 c.1013C>T and coat colour alleles were performed. Exons of DDB2 were sequenced in four cases and two controls. Associations were analysed by Chi-square or Fisher's exact tests and relative risk was calculated.

RESULTS

Homozygosity for DDB2 c.1013C>T was significantly associated with ocular SCC (P = 7.4 × 10^-7 ). Seventy-six per cent of affected horses were homozygous for the variant. Relative risk for homozygous horses developing SCC was 4.0 (P = 1.0 × 10^-4 ). Sequencing DDB2 did not identify a variant more concordant with disease phenotype. An association between disease and coat colour loci was not identified.

MAIN LIMITATIONS

Phenotyping was determined at a single timepoint. Each included horse genotyped as chestnut, so association with this MC1R variant could not be investigated.

CONCLUSIONS

A missense variant, DDB2 c.1013C>T, p.Thr338Met, is a risk factor for ocular SCC in Belgian horses. A genetic risk test is commercially available.

Ultraviolet Radiations: Skin Defense-Damage Mechanism

UV-radiations are the invisible part of light spectra having a wavelength between visible rays and X-rays. Based on wavelength, UV rays are subdivided into UV-A (320-400 nm), UV-B (280-320 nm) and UV-C (200-280 nm). Ultraviolet rays can have both harmful and beneficial effects. UV-C has the property of ionization thus acting as a strong mutagen, which can cause immune-mediated disease and cancer in adverse cases. Numbers of genetic factors have been identified in human involved in inducing skin cancer from UV-radiations. Certain heredity diseases have been found susceptible to UV-induced skin cancer. UV radiations activate the cutaneous immune system, which led to an inflammatory response by different mechanisms. The first line of defense mechanism against UV radiation is melanin (an epidermal pigment), and UV absorbing pigment of skin, which dissipate UV radiation as heat. Cell surface death receptor (e.g. Fas) of keratinocytes responds to UV-induced injury and elicits apoptosis to avoid malignant transformation. In addition to the formation of photo-dimers in the genome, UV also can induce mutation by generating ROS and nucleotides are highly susceptible to these free radical injuries. Melanocortin 1 receptor (MC1R) has been known to be implicated in different UV-induced damages such as pigmentation, adaptive tanning, and skin cancer. UV-B induces the formation of pre-vitamin D3 in the epidermal layer of skin. UV-induced tans act as a photoprotection by providing a sun protection factor (SPF) of 3-4 and epidermal hyperplasia. There is a need to prevent the harmful effects and harness the useful effects of UV radiations.

Defect Reconstruction of the Nose After Surgery for Nonmelanoma Skin Cancer: Our Clinical Experience

Objective

This study aimed to investigate reconstruction methods according to nasal subunits in patients who were surgically treated with diagnosis of non-melanoma skin cancer of the nose.

Methods

All patients were retrospectively investigated. This study was conducted between April 2004 and December 2010; 180 patients who were surgically treated with diagnoses of skin basal cell carcinoma, squamous cell carcinoma, cancer of skin appendages, and precancerous lesions and 194 lesions were included. The types of repair performed were divided into seven main groups: Secondary healing, primary closure, skin graft, local flap, auricular composite graft, subtotal reconstruction and prosthesis application.

Results

Among the 180 patients, 110 (61.1%) were males and 70 (38.9%) were females. The mean duration of follow-up was 39.8 (range, 32-81) months. Repair was by a local flap, a primary suture, a skin graft, and an auricular composite graft in 133, 16, 38, and 2 defects, respectively. Four defects were left for secondary healing. A prosthesis was applied to one patient. Totally, 194 defects were treated by surgery.

Conclusion

Although nonsurgical treatment options such as radiotherapy or cryotherapy may be effectively used, surgery is the main treatment option for cancer of the nasal skin. Nasal subunits have distinct characteristics; thus, optimal reconstruction should be preferred for each subunit. The objective of the reconstruction is not only closing the defect. Closing the defect appropriately with the optimal flap and in proper with the aesthetic subunits is the most important point in reconstruction of the nose.

Arbeitsbedingte Synkanzerogenese an der Haut - Zur kombinatorischen Einwirkung zweier Karzinogene der Berufskrankheiten-Liste

HINTERGRUND

Die Synkanzerogenese am Hautorgan, wissenschaftlich unstrittig, spiegelt sich im monokausal geleiteten Berufskrankheiten (BK)-Recht nicht wider. Nichtmelanozytäre Hauttumoren und deren Vorläuferläsionen können nur nach Einzelprüfung der BK-Nrn. 5103 und 5102 anerkannt werden.

METHODIK

Retrospektive Auswertung von 28 zwischen September 2012 und September 2015 begutachteten Fällen (Altersmedian 72,5 J.) mit nichtmelanozytären Hauttumoren und deren Vorläuferläsionen und arbeitsbedingter Exposition gegenüber natürlicher UV-Strahlung und polyzyklischen aromatischen Kohlenwasserstoffen.

ERGEBNISSE

In allen 28 Fällen sahen wir die arbeitstechnischen Voraussetzungen nach den BK-Nrn. 5103 und 5102 als erfüllt an. In 26 Fällen (93 %) empfahlen wir die Hautkrebserkrankung als BK-Tatbestand nach den Nrn. 5103 und 5102 anzuerkennen. Dem folgte der Unfallversicherungsträger in vier Fällen. Achtmal wurde die Anerkennung nur nach BK-Nr. 5103, zehnmal nur nach BK-Nr. 5102 und viermal gar nicht ausgesprochen.

SCHLUSSFOLGERUNGEN

Bei nichtmelanozytären Hauttumoren oder deren Vorläuferläsionen an UV-exponierten Hautarealen mit ausreichend kumulativer arbeitsbedingter natürlicher UV-Strahlenexposition und bei arbeitsbedingter Exposition gegenüber polyzyklischen aromatischen Kohlenwasserstoffen sollten mittels BK-Anzeige die "BK-Nrn. 5103 und 5102 im Sinne der Synkanzerogenese" gemeldet werden. Neben der gerechteren Wiedergabe der Arbeitsplatzrealitäten in einem solchen Feststellungsverfahren kann es dann im Konkreten auch zur Anerkennung von Basalzellkarzinomen kommen, die ansonsten, bei alleiniger Prüfung der BK-Nr. 5103, herausgerechnet würden.

Basal cell carcinoma: what's new under the sun

Basal cell carcinoma (BCC) is the most common skin cancer in white populations with an increasing incidence worldwide, thereby imposing an important public health problem. Its etiology is still unclear, but existing data indicate that the risk for BCC development is of multifactorial origin and results from the interplay of both constitutional and environmental factors. Yet, UV radiation (UVR) is believed to be the predominant causative risk factor in the pathogenesis of BCC. For years, BCC and squamous cell carcinoma (SCC) have been grouped together as "nonmelanoma skin cancer." However, it seems that there are considerable biologic differences between BCC and SCC, and thus each type of epithelial cancer should be addressed separately. The present review provides an overview of the intriguing etiologic link of BCC with UVR and attempts a comprehensive review of recent epidemiologic and molecular evidence that supports this association.

Basal cell carcinoma of the eyelid in Finland during 1953−97

PURPOSE

To study the incidence of basal cell carcinoma (BCC) of the eyelid in Finland.

METHODS

We studied 6241 cases of BCC of the eyelid reported to the nationwide Finnish Cancer Registry during 1953-97. We determined the age- and sex- specific incidence rates and overall rates adjusted for age to the world standard population, and social class- and occupation-specific standardized incidence ratios, with the total Finnish population as reference.

RESULTS

The incidence rates of BCC of the eyelid varied between 0.7 and 3.0 per 100 000 person-years in men and between 0.5 and 2.8 per 100 000 person-years in women during the study period. The age-adjusted incidence rates of BCC of the eyelid increased during 1953-87 (p < 0.0001). The incidence of BCC of the eyelid rose significantly with age. There were no significant differences in standardized incidence ratios (SIRs) for BCC of the eyelid between different social class and occupation categories.

CONCLUSION

Age-adjusted incidence rates showed that BCC of the eyelid was more than twice as frequent during 1978-97 than before 1968. Ageing may partly explain the increased incidence of BCC of the eyelid, whereas there were no differences in the SIRs for BCC of the eyelid between different social class and occupation categories in Finland.

UVA-induced immunosuppression

It has previously been demonstrated that chronic low-dose solar-simulated ultraviolet (UV) radiation can induce both local and systemic immunosuppression as well as tolerance to a topically applied hapten. Epidermal cells from UV-irradiated mice inhibit spontaneous regression of tumours indicating that UV-induced immunosuppression is likely to permit the outgrowth of developing UV-induced skin tumours. We have used a chronic low-dose UV-irradiation protocol to investigate the effects of UVA on the skin immune system of C3H/HeJ mice. Irradiation with UVA + B significantly suppressed the local and systemic primary contact sensitivity (CS) response to the hapten TNCB. Furthermore UVA + B reduced Langerhans cell (LC) and dendritic epidermal T cell (DETC) numbers in chronically UV-irradiated mice. UVA-irradiation induced local, but not systemic, immunosuppression and reduced LC (32%) but not DETC from the epidermis compared to the shaved control animals. Treatment of mice with UVA + B or UVA radiation also induced an impaired secondary CS response, and this tolerance was transferable with spleen cells. Therefore exposure of C3H/HeJ mice 5 days per week for 4 weeks with UVA can induce local immunosuppression and tolerance. One of the mechanisms by which UVA affects biological systems is production of reactive oxygen species. We have also shown that Vitamin E, an inhibitor of lipid peroxidation, prevents UV-induced immunosuppression and loss of LC. It is possible that the UVA in UV radiation induces epidermal lipid peroxidation which stimulates LC migration from the epidermis, thus contributing to UV-induced immunosuppression. Hence, inhibition of epidermal lipid peroxidation by Vitamin E may provide some protection to the skin immune system from these effects of UV.

The role of melanocytes in the repair of UV related DNA damage in keratinocytes

Epidermal pigmentation and UV exposure are related to the incidence of skin tumors. There is a higher incidence of UV related skin tumors in populations with low pigment and in vitiligo patients, resulting from DNA damage. Normally DNA repair processes set in with the expression of PCNA in the keratinocyte. The present study was conducted on the marginal zone skin in vitiligo. Whole skin organ cultures irradiated with increasing doses of UV in the 280400 nm range show that in the depigmented area there is no expression of PCNA by the keratinocytes. In comparison, the marginal zone keratinocytes show a dose related positivity in the presence of UV responsive melanocytes. These photoresponsive melanocytes show dendricity and cytoplasmic PCNA positivity. The melanocytes interact with keratinocytes by active melanosome transfer. From this study it is suggested that this involves transfer of PCNA as well. The present study indicates the differentiating keratinocytes in skin do not express PCNA but appear to be dependent on active UV responding melanocytes for DNA repair. This factor could play an important role in the occurrence of UV-related skin tumors.

The epidemiology of skin cancer

BACKGROUND

The incidence of skin cancer is increasing at an alarming rate.

OBJECTIVE

To discuss current epidemiologic data concerning the incidence, morbidity, environmental influences, predisposing, host conditions, precursor lesions, and prevention of melanoma and nonmelanoma (basal and squamous cell) skin cancer.

METHODS

The current literature was reviewed in order to provide current epidemiologic data for melanoma, basal cell carcinoma (BCC), and squamous cell carcinoma (SCC).

RESULTS

Skin cancer is exceedingly common and the incidence is rising rapidly. Although the mortality rate for nonmelanoma skin cancer (NMSC) is decreasing, that of melanoma is increasing. Both NMSC and melanoma are associated with significant morbidity. Whereas chronic sun exposure is the main cause of NMSC, the development of melanoma appears to be related to intense, intermittent sun exposure. Ozone depletion has contributed to rising incidence rates of both NMSC and melanoma. In contrast to NMSC, there is not a direct relationship between ultraviolet radiation and melanoma. Genetic susceptibility significantly increases the lifetime risk of acquiring melanoma. There is no precursor lesion for BCC. Precursor lesions for invasive SCC include actinic keratoses and SCC in situ. Melanoma may arise from benign nevi and dysplastic nevi. Prevention of melanoma and NMSC is extremely important since prognosis improves with early detection. Prevention may be achieved by educating patients and physicians how to detect skin cancers early and by decreasing or eliminating exposure to ultraviolet light.

CONCLUSION

The incidence of skin cancer has reached epidemic proportions. Only through heroic efforts by health care professionals and the general public to prevent the development or progression of skin cancer will this epidemic be abated.

Is dermatologic usage of coal tar carcinogenic? A review of the literature

BACKGROUND

Coal tar ointments have been used for decades in the treatment of various dermatoses, most notably eczema and psoriasis. Occupational exposure to coal tar poses an increased risk of developing cutaneous malignancies. The evidence of an increased risk of skin cancer in humans, as a result of dermatologic usage of tar, however, is conflicting.

OBJECTIVE

A consensus on the carcinogenicity of tar is sought.

METHODS

The existing literature (in vitro, animal, and human studies) on this subject is reviewed.

RESULTS

The carcinogenicity of coal tar has clearly been demonstrated by in vitro and animal studies, and appears to be potentiated by concomitant use of ultraviolet radiation. Systemic absorption of mutagens from topically applied tar has been demonstrated in humans. Epidemiologic studies in humans, however, have not definitively shown an increase in skin cancer with therapeutic use of tar.

CONCLUSIONS

Conclusive evidence for the carcinogenicity of tar used in dermatologic practice is lacking. Further controlled studies are necessary.

Physiological and toxicological changes in the skin resulting from the action and interaction of metal ions

The human environment contains more than 50 metal or metalloid elements. At least 15 are recognized as trace elements, with zinc, calcium, copper, magnesium, and iron having specific roles in skin morphogenesis and function. The present review focuses on the presumed role of metal ions in the skin, their competition for carrier proteins, and membrane receptors. Evidence presented shows that the balance of trace metal ions is critical for normal skin and repair mechanisms following injury. Xenobiotic ions can impair this balance, leading to pathological change. The skin acts as an organ of elimination of excess trace metals and xenobiotic ions from the body, but mechanisms of voidance vary for different metals. Metal ions are an important cause of allergies, and evidence is presented to show that the majority of metals or metal compounds can induce allergic changes. Except for chromium and nickel, which are among the most common human allergens, animal models have provided little information. At least cadmium, thorium, lead, chromium, nickel, beryllium, and arsenic and proven or putative carcinogens in animals or humans on the basis of cytological or epidemiological evidence. However, only arsenic exhibits a clear predilection for the skin. Other metals such as gold can induce subcutaneous sarcoma following injection, but the relevance of this observation in terms of human occupational risk is discounted.

Sun exposure and non-melanocytic skin cancer

Non-melanocytic skin cancer has long been regarded as one of the harmful effects of solar ultraviolet (UV) radiation on human health. In this review, we examine epidemiologic evidence linking sun exposure and skin cancer coming from both descriptive studies in populations and analytical studies involving estimates of exposure in individuals. Particular attention is given to the quality of the published data. The epidemiologic evidence that sun exposure causes skin cancer is mainly indirect. Incidence or mortality is inversely related to latitude in populations of mainly European origin (e.g., the United States, Australia), and is higher in people born in Australia (high ambient solar radiation) than in migrants to Australia from the United Kingdom (lower ambient radiation). Skin cancer occurs mainly at sun-exposed body sites and in people who are sensitive to the sun; a reduced capacity to repair UV-induced DNA damage appears to increase the risk. The direct evidence linking sun exposure and skin cancer is weaker with few well-conducted studies of sun exposure in individuals. Mostly, studies of total sun exposure have not found statistically significant positive associations; those that did, had not adjusted for potential confounding by age and gender and thus their interpretation is limited. Studies of occupational sun exposure had relative risks not greater than 2.0; recreational exposure has been little studied. Other measurements, less direct but potentially less prone to measurement error, are sunburn (not evidently associated with skin cancer risk) and indicators of benign cutaneous sun-damage (strongly associated but lacking empirical evidence that sun exposure is their main cause). Many questions remain about the relationship between sun exposure and skin cancer.

Basal cell carcinoma on the lower extremity

From 1987 to 1990, 21 of 648 patients with basal cell carcinomas (BCCs) had their lesion located on the leg. Basal cell carcinomas in this location are uncommon. Women outnumbered men by 1.6:1. The majority of patients had types I and II skin. Most reported residence in the southwestern United States for many years. Recreational sun exposure was extensive and dominated by activities in which exposure of the legs was common. Most lesions were recognized clinically and located on the anterior lower leg. The most frequent histologic description was superficial BCC. Treatment was with electrodesiccation and curettage or excision.

High prevalence of skin cancer in World War II servicemen stationed in the Pacific theater

BACKGROUND

A large proportion of our World War II patients with skin cancer had been stationed in the Pacific.

OBJECTIVE

Our purpose was to determine whether a statistically greater number of World War II servicemen with skin cancer were stationed in the Pacific than the number stationed in Europe.

METHODS

In a consecutive survey of 370 World War II servicemen with skin cancer who were stationed abroad, place of service, skin cancer types, skin type, ethnic background, and estimated average hours outdoors per day during their lifetime were determined. The number of veterans stationed in the Pacific and the number stationed in Europe with respect to these data were analyzed with the chi-square test.

RESULTS

A statistically significantly greater number of Pacific veterans than Europe veterans had basal cell or squamous cell carcinomas.

CONCLUSION

A few months to a few years of prolonged sun exposure in a high-sun-intensity area may result in skin cancer development many years after exposure.

Squamous cell carcinoma of the skin (excluding lip and oral mucosa)

The striking impression obtained from reviewing the cancer literature is how difficult it is to analyze the data for answers to many important biologic, behavioral, prognostic, and therapeutic questions about squamous cell carcinoma of the skin. This article addresses current concepts, controversies, and management of cutaneous squamous cell carcinoma (excluding the lip and oral mucosa).

Identification of a transforming ras oncogene in an ultraviolet radiation-induced corneal tumor of Monodelphis domestica

Chronic exposure of the gray, short-tailed oppossum, Monodelphis domestica to ultraviolet radiation (UVR) induces mesenchymal tumors of the cornea. High molecular weight DNA samples from 6 UVR-induced corneal tumors were assayed for their ability to transform NIH 3T3 cells to tumorigenicity. NIH 3T3 cells transfected with DNA from 5 of the corneal tumors produced 14 tumors in nude mice. Cell lines were established from these tumors. DNA from 13 of 14 tumor cell lines contained repetitive opossum DNA sequences. Southern blot analysis revealed that DNA from 3 of 4 cell lines derived from tumorigenic NIH 3T3 cells transfected with DNA from a single oppossum tumor contained opossum Ki-ras oncogene sequences in addition to the murine Ki-ras gene. Northern blot analysis of mRNA from a mouse tumor cell line containing opossum Ki-ras gene sequences showed mRNA species identical in size to opossum Ki-ras mRNA, as well as murine Ki-ras mRNA species. These results suggest that an activated Ki-ras oncogene was present in one of the original opossum corneal tumors tested. Thus, activation of Ki-ras may play a role in the development of UVR-induced corneal tumors in Monodelphis domestica. Further characterization of ras oncogenes in these opossum tumors may provide information on the molecular mechanisms by which UVR induces corneal tumors in this species.

Langerhans cell migration into ultraviolet light-induced squamous skin tumors is unrelated to anti-tumor immunity

There has been much speculation as to the role of Langerhans cells (LC) in the induction of anti-tumor immunity. Whereas there is considerable circumstantial evidence that disruptions in the density and function of these cells during the early stages of ultraviolet (UV) light- and chemical carcinogen-induced carcinogenesis may be important for enabling developing neoplasms to escape immune destruction, the role of the large number of these cells found infiltrating developed skin tumors is less clear. To investigate this we have compared the LC density infiltrating transplanted non-immunogenic and immunogenic UV-induced murine tumors as well as LC in the epidermis overlying the tumors. Whereas two non-immunogenic tumor lines attracted large numbers of Ia+ dendritic cells, an immunogenic tumor line did not. Similar results were obtained whether the tumors were transplanted into syngeneic immunocompetent or athymic immunodeficient mice. Hence, there was no relationship between tumor immunogenicity or host immunocompetence and Ia+ dendritic cell density. Furthermore, there was no correlation with the pattern of T-cell infiltration of the tumors or CD4/CD8 cell ratio. Our results also indicate that whereas UV light decreased Ia+ cell density, both in the epidermis and the tumors, it did not inhibit the tumors from attracting Ia+ dendritic cells. Thus, the Ia+ dendritic cells infiltrating skin tumors are unlikely to indicate a host immune response to the tumor, but are more likely to be attracted by tumor-derived cytokines.

Pigmentary and cutaneous risk factors for non-melanocytic skin cancer--a case-control study

The roles of ethnic origin, pigmentary traits, sun sensitivity and other cutaneous characteristics as risk factors for basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC) were examined in a case-control study of prevalent and incident cases of histopathologically confirmed skin cancers. Two hundred and twenty six confirmed cases of BCC, 45 of SCC and 1,015 controls with no lesions were identified in a population-based survey of skin cancer in 1987 in Geraldton, Western Australia. The risk of both cancers was higher in native-born Australians than in migrants. The risk of BCC decreased with increasing age at arrival in Australia. Southern European ancestry was strongly protective against BCC (for any southern European grandparents) and SCC (no case of SCC had any grandparents of southern European origin). Inability to tan was the strongest pigmentary risk factor for both BCC and SCC. Among factors that incorporated a measure of sun exposure as well as sun sensitivity, freckling on the arm in childhood was important for both cancers, the number of moles on the back was important for BCC, and forearm skin colour and having a permanent colour difference between the neck and adjacent protected areas were important for SCC. Among measures of sun damage to the skin, solar elastosis of the neck was a strong risk factor for both BCC and SCC, loss of fine texture of the skin of the back of the hands (as measured by cutaneous microtopography) was important for BCC and telangiectasia of the face for SCC. When all important variables for each cancer were examined together in a single model with age, sex, migrant status or age at arrival in Australia, and ethnicity, in ability to tan, solar elastosis of the neck, and the number of moles on the back were independently significant risk factors for BCC and solar elastosis of the neck and having a permanent colour difference between the neck and adjacent protected areas were independently significant risk factors for SCC. The effects of age at arrival or migrant status and ethnic origin remained important in the models incorporating these factors. A history of ever having acne and a history of warts were protective for BCC and a history of acne was protective for SCC.

Ultraviolet radiation-induced skin tumors in a South American opossum (Monodelphis domestica)

A total of 19 male and 21 female South American opossums (Monodelphis domestica) were exposed to 250 J/m2 ultraviolet radiation from FS-40 sunlamps (280-400 nm) three times weekly for 70 weeks. The backs of the opossums were shaved as necessary to remove hair. In order to prevent photoreactivation of ultraviolet radiation-induced pyrimidine dimers by the light-dependent photolyase enzyme of the opossum, ultraviolet radiation-exposed opossums were housed under red lights (600-800 nm). The opossum photolyase requires light in the 320-450 nm range for its activity. Twenty-nine control opossums (14 males and 15 females) were irradiated by fluorescent lights with emission spectra primarily in the visible light range (320-700 nm); these control opossums were also housed under red lights, and their backs were also shaved to remove hair. No skin tumors were observed in control opossums, while ultraviolet radiation-exposed opossums developed a variety of hyperplastic and neoplastic skin lesions on the backs and on a single ear. Hyperplastic lesions included foci of epithelial hyperplasia, dermal fibroplasia, and focal proliferation of dermal melanocytes. A total of 20 ultraviolet radiation-exposed opossums (50%) developed skin tumors, and 13 opossums (32.5%) had more than a single tumor. Epithelial tumors included 25 papillomas, four keratoacanthomas, seven carcinomas in situ, three microinvasive squamous cell carcinomas, two invasive squamous cell carcinomas, and a single basal cell tumor. Ten dermal spindle cell tumors also occurred; most of these appeared to be fibrosarcomas. Two benign melanomas and one malignant melanoma were observed.

Skin cancer in Geraldton, Western Australia: a survey of incidence and prevalence

A survey of the incidence and prevalence of non-melanocytic skin cancer in Geraldton, Western Australia, was undertaken in November 1987. All residents aged 40 to 64 years whose names were on the electoral roll on August 1, 1987 were invited to undergo a whole-body skin examination by a dermatologist. When a skin cancer was suspected, participants were referred for treatment to their usual medical practitioner. Subjects were asked to recall incident skin cancers over the preceding two years, and medical records were searched for confirmatory evidence. Histological confirmation of all lesions, both prevalent and incident, was sought and sections were obtained for a standardized review. The prevalence of confirmed non-melanocytic skin cancer in those aged 40 to 64 years was 7.0% in men and 4.7% in women. The prevalence of basal-cell carcinoma (BCC) was 6.5% in men and 4.5% in women while the prevalence of squamous-cell carcinoma (SCC) was 1.2% in men and 0.3% in women. The estimated incidence rate of non-melanocytic skin cancer in this age group was 1560 per 100,000 person-years. The estimated incidence rate of BCC in men was 1335 per 100,000 person-years, and in women 817 per 100,000, while in men the estimated incidence rate of SCC was 890 per 100,000 person-years, and in women it was 289 per 100,000 person-years.

The senile epidermis: environmental influences on skin ageing and cutaneous carcinogenesis

There is a wealth of new knowledge regarding mechanisms of carcinogenesis and their interaction with senescence and environmental insults, particularly on the effects of UV irradiation on the skin. Innovations and advances in tissue culture techniques now permit in vitro studies of keratinocytes and other benign and malignant skin-derived cells. The ageing processes and cutaneous neoplasia, therefore, can now be studied at the cellular level. New insights regarding the interrelationship of ageing, environment and cutaneous neoplasia are close at hand. Depletion in the number of Langerhans cells and suppression of their function in ageing and UV-exposed skin may allow tumour cells to overcome the host's defence system. The potential increase in UV irradiation due to depletion of the ozone layer may increase the incidence of skin tumours. Carcinogenesis involves three distinct steps: initiation, promotion, and malignant conversion. The mechanism has been studied in mice, where it is suggested the c-ras oncogene may play an important role.

Protection against chemically induced skin tumorigenesis in SENCAR mice by tannic acid

Tannic acid, a naturally occurring dietary polyphenol, was evaluated as a possible anticarcinogen in an initiation-and-promotion skin tumorigenesis protocol. In the 2-stage tumor protocol in SENCAR mice, using DMBA, BP and MNU as the initiating agents followed by twice-weekly applications of TPA as tumor promotor, tannic acid was found to be an effective inhibitor of tumor formation whether the tumor data are considered as cumulative number of tumors, percentage of mice with tumors or tumors/mouse. After 9 weeks of TPA application, the number of tumors/mouse in the groups receiving DMBA, BP and MNU were 32.10 +/- 3.18, 3.70 +/- 0.55 and 2.00 +/- 0.53, respectively, whereas the corresponding numbers in the DMBA, BP and MNU groups receiving prior applications of tannic acid were 11.50 +/- 2.38, 0.35 +/- 0.15 and 0.35 +/- 0.13, respectively. These results suggest that tannic acid may prove useful in reducing the risk of chemically-induced skin tumorigenesis.

Ultrastructural changes produced in Ehrlich ascites carcinoma cells by ultraviolet-visible radiation in the presence of melanins

Irradiation of Ehrlich ascites carcinoma (EAC) cells in the presence of pheomelanin, i.e., red hair melanin (RHM), has been reported to produce extensive cell lysis. Irradiation in the presence of eumelanin, i.e., black hair melanin (BHM), or irradiation in the absence of either type of melanin did not produce this effect. We observed that RHM particles penetrated the cell membrane without apparent structural damage to the cell or the cell membrane. Irradiation of the cells in the absence of melanin did not produce any changes in the ultrastructure of the cells. Incubation of the cells in the dark in the presence of RHM produced only minor structural, mainly cytoplasmic changes. Irradiation of the cells in the presence of RHM produced extensive ultrastructural changes prior to complete cell lysis; these changes were more severe than the effects of incubation of the cells in the dark in the presence of RHM. When the cells incubated in the dark or irradiated in the presence of latex particles or either one of the eumelanins particles, viz. BHM or synthetic dopa melanin, these particles did not penetrate into the cells or produce any ultrastructural changes. These particles were in fact not even ingested by the cells.

The development of contact hypersensitivity in mouse skin is suppressed by tumor promoters

The ability of tumor promoters to suppress the development of contact hypersensitivity (CHS) was assessed by the mouse ear swelling assay. Application of the complete or second stage tumor promoters phorbol-12-myristate-13-acetate (PMA, 2 micrograms), croton oil (1%), benzoyl peroxide (20 mg), mezerein (2 micrograms), or phorbol-12-retinoate-13-acetate (PRA, 2 micrograms) to the abdominal surface of CF-1 female mice for 1 week (three treatments) prior to the sensitization of the same location with 0.5% 1-chloro-2,4-dinitrobenzene (DNCB) resulted in a 50% suppression (p less than 0.05) of the CHS response to DNCB. The first stage tumor promoters 4-O-Me-PMA (80 micrograms), calcium ionophore A23187 (80 micrograms), hydrogen peroxide (15%) and the non-promoting analogs phorbol-12,13-diacetate (PDA, 20 micrograms), phorbol (80 micrograms) or acetone did not suppress the response. The suppression of the development of CHS caused by PMA was dependent on the promoter being applied at the site of induction and was inhibited by application of the phospholipase A2 inhibitor dibromoacetophenone (100 micrograms), the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA, 100 micrograms), or the antiinflammatory steroid fluocinolone acetonide (2 micrograms). Application of PMA or mezerein 24 h prior to challenge with DNCB, to the ears of mice previously sensitized with DNCB resulted in a significant enhancement of the ear swelling response by 60% and 110%, respectively, compared with controls. The results demonstrate that tumor promoters suppress the development of CHS, and suggest the possibility that second stage promotion may involve suppression of the development of a tumor specific immune response.

Additive effects of ultraviolet B and crude coal tar on cutaneous carcinogen metabolism: possible relevance to the tumorigenicity of the Goeckerman regimen

The effect of cutaneous exposure to ultraviolet B (UVB) radiation alone, to crude coal tar (CCT) alone, and to the combination of UVB and CCT on the inducibility of the microsomal cytochrome P-450-dependent carcinogen-metabolizing enzyme aryl hydrocarbon hydroxylase (AHH) and other monooxygenases such as 7-ethoxyresorufin O-deethylase (ERD) and 7-ethoxycoumarin O-deethylase (ECD) activities in the skin of neonatal rats was studied. Exposure of the animals to UVB (400-1600 mJ/cm2) alone resulted in a dose-dependent increase in cutaneous enzyme activities. At a UVB dose of 1200 mJ/cm2 increases in AHH, ECD, and ERD were 194%, 115%, and 244%, respectively. A single topical application of CCT (10 ml/kg) 24 h before sacrifice resulted in significant induction of AHH (350%), ECD (921%), and ERD (796%) activities. Treatment of animals with the same dose of CCT followed by UVB exposure resulted in additive and/or synergistic effects on AHH (858%), ECD (1229%), and ERD (1166%) activities in the skin. In contrast, exposure of animals to UVB prior to CCT application had effects no different from those of CCT alone. Epoxide hydrolase and glutathione S-transferase activities in skin from all experimental groups were not different from those of controls. High-pressure liquid chromatographic analysis of the metabolism of benzo[a]pyrene (BP) by cutaneous microsomes prepared from animals treated with UVB alone, CCT alone, and the combination of UVB and CCT revealed increased formation of all the metabolites in each experimental group. The largest increase in metabolite formation occurred in animals receiving CCT followed by UVB exposure. The inducibility of trans-7,8-diol formation by UVB alone and CCT alone was 203% and 435%, respectively, whereas with CCT followed by UVB it was 1065%. The differential responses in AHH activity were found to parallel the capacity of skin microsomal enzymes to enhance the binding of [3H]-BP to DNA. These studies indicate that the sequence of exposure to the components of the Goeckerman regimen in rodents greatly influences metabolic activity in skin. When applied in the same sequence employed in the Goeckerman regimen (CCT followed by UVB exposure) the additive effect upon catalytic activity essential for cancer initiation suggests a possible mechanism for the enhancement of human skin cancer in individuals exposed to this therapeutic regimen.

Altered patterns of cutaneous xenobiotic metabolism in UVB-induced squamous cell carcinoma in SKH-1 hairless mice

Cutaneous xenobiotic metabolizing enzymes including aryl hydrocarbon hydroxylase (AHH), 7-ethoxycoumarin O-deethylase (ECD), epoxide hydrolase (EH) and glutathione S-transferase (GST) activities were examined in SKH hairless mice chronically irradiated with UVB to induce squamous cell carcinoma (SCC). Enzyme activities in irradiated tumor-bearing skin were compared to those present in the skin of nonirradiated control animals as well as in unirradiated non-tumor bearing skin sites of the SCC-bearing mice. The inducibility of skin AHH and ECD in each set of animals was assessed following a single topical application of coal tar (1 ml/100 g). Enzyme-mediated binding of [3H]benzo(a)pyrene (BP) and its metabolite 7 beta,8 alpha-dihydroxy-9 alpha,10 alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene (BPDE-I) to epidermal DNA was also evaluated. Basal AHH and ECD activities in microsomes from UVB-irradiated SCC-bearing dorsal skin were 4.6- and 4.8-fold lower than those in dorsal skin of nonirradiated control animals. Enzyme activities in non-tumor bearing ventral skin from the UVB-irradiated SCC-bearing mice also were 2.2 to 2.8-fold lower as compared to activities in the nonirradiated control animals. The reduction in AHH activity paralleled the levels of enzyme-mediated binding of radiolabeled BP metabolites and of BPDE-I to epidermal DNA. GST activity was found to be increased (173%) in non-tumor bearing ventral skin of UVB-irradiated mice whereas no difference in activity between SCC-bearing dorsal skin and dorsal skin of control animals could be detected. EH activity was unchanged in each group of animals. Treatment with topically applied coal tar resulted in higher inducibility of AHH and ECD in both SCC-bearing (13-fold) as well as in non-tumor skin sites (6-fold) of UVB-irradiated mice than in skin of control animals (3-fold). Coal tar application also increased the covalent binding of [3H]BP and of the metabolite BPDE-I to skin DNA. This was greater in SCC-bearing dorsal skin (119-129%) than in nonirradiated skin of control animals (48-62%). Our studies suggest that the metabolism of BP by cutaneous cytochrome P-450 dependent monooxygenases is impaired in skin of mice irradiated chronically with UVB. The higher inducibility of these monooxygenases by topically applied coal tar and the enhancement of the associated enzyme-mediated covalent binding of BP metabolites and BPDE-I to epidermal DNA indicate that repetitive exposure of mammalian skin to UVB radiation can profoundly alter the activity and the inducibility of drug and carcinogen metabolizing enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)

Risk factors of squamous cell carcinoma of the skin. A case-control study in the Montreal region

A matched case-control study was undertaken to assess the relative risk associated with known and suspected risk factors of squamous cell carcinoma of the skin among patients in the Montreal region. Three hundred eleven cases histologically diagnosed in 1977 and 1978 in 12 hospitals and meeting strict definition criteria were identified. With the exception of six cases, two controls were matched to each case for sex, age, and hospital of diagnosis. A logistic regression analysis was done. The known host risk factors (eye and hair color, complexion, descent) and nonoccupational sunlight exposure were found to be operative in the Montreal region. After adjusting for these factors, occupational sunlight exposure appeared to be a risk factor. An association was then observed between the risk of squamous cell carcinoma of the skin and tobacco smoking and the use of a sunlamp. Relative risks associated with the above-mentioned factors were estimated.

The biology of basal cell carcinoma: a review

Features of basal cell carcinoma are reviewed within the broad categories of growth characteristics, histogenesis, ultrastructural features, biochemical properties, site of origin, metastatic potential, and immunobiology. Biologic features that pertain to host-tumor interactions are emphasized. Perhaps a better understanding of these host-tumor relationships will offer more effective methods of treating and preventing these neoplasms in the future.

Age-associated changes in the skin

Like all organ systems, the skin manifests an age-associated loss of functional capacity and increasing vulnerability to injury and certain disease states. Knowledge of the aging changes in normal skin assists the physician in diagnosis and management of certain dermatoses. Awareness of the important interactions between aging skin and the environment could lead to prevention of many disorders. The burden of skin disease for the elderly is often underestimated. It is psychosocial as well as medical, and although mortality is low, morbidity is high. A rational and caring approach by the general practitioners, family physicians, internists, and geriatricians responsible for this patient population should greatly improve the situation.

Cancer risks associated with agriculture: epidemiologic evidence

Despite their generally favorable mortality experience, general occupational surveys of farmers suggest they have elevated risks of cancer of the lymphatic and hematopoietic systems, stomach, prostate, brain, and skin. Since farmers often serve in the role of mechanic, carpenter, welder, pesticide applicator, and veterinarian, they may be exposed to many potentially hazardous substances. The types and levels of exposures have been discussed by others earlier in the program. The evidence is strongest for the association between farming and risk of leukemia. However, the specific leukemogenic agent or agents have yet to be identified. Leukemia excesses among poultrymen and dairy farmers suggest involvement of zoonotic viruses, while associations with crop production is more indicative of pesticide usage. The associations regarding other cancers (i.e., Hodgkin's disease, non-Hodgkin's lymphoma, multiple myeloma, soft-tissue sarcoma, and cancers of the stomach, brain, and prostate) are even less clear. However, the Swedish reports of high risk of soft-tissue sarcomas and lymphomas among persons exposed to herbicides is particularly disconcerting and underscores the urgent need for similar epidemiologic studies in the U.S. Several case-control interview studies are underway that should help clarify the role of agricultural factors in the origin of various cancers. NCI is sponsoring studies of leukemia and non-Hodgkin's lymphoma among men from Minnesota and Iowa. Detailed information on farm practices and pesticide usage is being gathered. A study of soft-tissue sarcoma, Hodgkin's disease, and non-hodgkin's lymphoma also has just been initiated. This investigation is located in Kansas, a major wheat producing area. A wheat producing area was selected because herbicides are more heavily used on this crop than insecticides. The major objective of this project is to evaluate the role of herbicides in the origin of these cancers. A case-control study of brain cancer has also recently been initiated. Although this study focuses on contact with petrochemicals, a complete work history will be obtained and would note any farm experience. These data may help clarify the reported association between brain cancer and farming.

Basal cell carcinoma in Queensland

An analysis is presented of a referred series of 1411 basal cell carcinomas treated by surgical excision and plastic surgical repair in which 259 were recurrent after previous other treatments. Of the 1,411 BCCs treated there were 10 BCCs which recurred (0.7% recurrence rate). A further 10 BCCs were primarily re-excised because of inadequate clearance around the tumour found on histological examination. (0.7% primary re-excision). The cases recurrent after previous treatment did not behave badly in terms of subsequent recurrence as they were widely excised and carefully observed in the postoperative years. Surgery must aim to be curative. We clearly define the tumour margin using magnification and mark an adequate clearance of surrounding normal tissue. This is then excised in width and depth. Repair of the defect is carried out to restore the area to as near normal as possible. Surgical repair is able to bring new tissue into the area to further enable it to withstand the rigours of the climate and not leave behind a premalignant scarred area.

Sunlight-skin cancer association in the dog: a report of three cases

Squamous cell carcinoma is one of the most frequently recognized neoplastic diseases of the canine integument, although few risk factors influencing tumor development have been clearly defined. Three dogs with cutaneous squamous cell carcinomas are reported. Tumors developed in lightly-pigmented, glabrous following chronic sunlight exposure and long period of dermatosis. Microscopic examination of tissues from the three dogs showed progressive development of epithelial hyperplasia through stages of solar keratosis-like lesions to invasive and metastatic squamous cell carcinoma.

Photocarcinogenesis: an overview

This paper reviews factors that have been reported to influence photocarcinogenesis in laboratory animals. Such factors include the sensitivity of the test animals, the amount of the ultraviolet radiation (UVR) delivered, the mode of its delivery, and interactions of other radiations or of chemicals in the process of carcinogenesis. New data are presented in these areas: reduction in the size of each unit dose (and thus an increase in dosing frequency) increases the carcinogenic effectiveness of a given lifetime dose; certain inbred strains of albino hairless mice exhibit heritable differences in their susceptibility; several chemicals are known to enhance photocarcinogenesis, but they appear to have so little in common, either structurally or functionally, that they offer limited guidance about which other compounds may be effective in this way. Prevention of long-term UVR effects on skin is a desirable goal; development of personal UVR dosimeters will aid in defining the quantitative nature of the problem; improved sunscreens should provide the means to achieve significant reduction in the incidence of UVR-induced human skin cancer.

Absorption of ultraviolet radiation by skin surface lipid

The UVR absorption spectrum for skin surface lipid was measured by spectrometry. Significant absorption occurred throughout the UVR range, with a maximum at 215 nm. We estimate that the lipid normally present on forehead skin is likely to reduce transmission at 300 nm by about 10%.