A dose-response curve for sun exposure and basal cell carcinoma

Pervasive Induction of Regulatory Mutation Microclones in Sun-exposed Skin

Carcinogen-induced mutations are thought near-random, with rare cancer-driver mutations underlying clonal expansion. Using high-fidelity Duplex Sequencing to reach a mutation frequency sensitivity of 4×10 -9 per nt, we report that sun exposure creates pervasive mutations at sites with ∼100-fold UV-sensitivity in RNA-processing gene promoters - cyclobutane pyrimidine dimer (CPD) hyperhotspots - and these mutations have a mini-driver clonal expansion phenotype. Numerically, human skin harbored 10-fold more genuine mutations than previously reported, with neonatal skin containing 90,000 per cell; UV signature mutations increased 8,000-fold in sun-exposed skin, averaging 3×10 -5 per nt. Clonal expansion by neutral drift or passenger formation was nil. Tumor suppressor gene hotspots reached variant allele frequency 0.1-10% via 30-3,000 fold clonal expansion, in occasional biopsies. CPD hyperhotspots reached those frequencies in every biopsy, with modest clonal expansion. In vitro, tumor hotspot mutations arose occasionally over weeks of chronic low-dose exposure, whereas CPD hyperhotspot mutations arose in days at 1000-fold higher frequencies, growing exponentially. UV targeted mini-drivers in every skin cell.

A UV-related risk analysis in ophthalmic malignancies: Increased UV exposure may cause ocular malignancies

Purpose

To explore the role of ultraviolet radiation (UVR) in the occurrence and development of various ocular malignancies.

Methods

In this article, we retrieved ocular malignancy data from the Global Cancer Observatory (GCO) and performed correlation analysis with the global UV index and sunshine duration. We searched for associated studies using the following databases: Embase, Pubmed, Cochrane Library, and Google Scholar. We conducted the literature by searching the Mesh terms denoting an exposure of interest ("UV radiation", "ultraviolet rays", and "ocular malignancies", All studies included are published until December 30, 2023 without language restrictions.

Results

The mechanisms and epidemiological statistics of UVR on the onset and progression of eyelid malignancies are the most studied and clear. The role of UVR in conjunctival melanoma is similar to that in eyelid melanoma. The relationship between uveal melanoma and UVR is controversial, however, it may have at least a certain impact on its prognosis. UVR causes ocular surface squamous neoplasia by further activating HPV infection.

Conclusions

UVR is a decisive risk factor for ocular malignancies, but the incidence of ultraviolet-induced tumors is also affected by many other factors. A correct and comprehensive understanding of the mechanisms of UVR in the pathogenesis of ocular malignant tumors can provide patients with more effective and selective immune regulation strategies.

Incidence of Nonmelanoma Skin Cancers in Alberta, Canada, From 2007 to 2018

BACKGROUND

Nonmelanoma skin cancer (NMSC) is the most common malignancy affecting Caucasian populations and has been seeing steady increases in incidence globally for decades. Our previous study (from Alberta, Canada) had shown a plateau in the incidence rates for NMSC. This contrasts with data from other regions within Canada and throughout the world that indicated a continued increase in incidence rates of NMSCs.

OBJECTIVES

The objective of this study was to provide an update on the trends in incidence of NMSC in Alberta, Canada, from 2007 to 2018.

METHODS

A retrospective analysis of patients from Alberta diagnosed with NMSC from 2007 to 2018 inclusive was conducted with data retrieved from Alberta Cancer Registry. Sex-, age-, anatomical location-, NMSC subtype-, stage-specific incidence rates and trends were examined.

RESULTS

From 2007 to 2018, overall incidence rates of NMSC increased by 36%. Invasive squamous cell carcinoma (SCC) and in situ SCC demonstrated the most significant increase, invasive SCC [annual percentage change (APC) 3.48, P = .014] and in situ SCC (APC 5.61, P = .0001). In addition, we were able to determine that females had the most significant increases in NMSC incidence rates from 2007 to 2018 particularly invasive SCC (APC 3.03, P = <.0001) and in situ SCC (APC 5.08, P = <.0001).

CONCLUSIONS

After initial levelling of NMSC incidence in Alberta in the early part of 21st century, the incidence of NMSC continues to increase over the past decade. The reasons for this change are not clear and likely multifactorial.

Occupational solar exposure and basal cell carcinoma. A review of the epidemiologic literature with meta-analysis focusing on particular methodological aspects

BACKGROUND

Numerous epidemiologic studies and a few systematic reviews have investigated the association between occupational solar exposure and basal cell carcinoma (BCC). However, previous reviews have several deficits with regard to included and excluded studies/risk estimates and the assessment of risk of selection bias (RoSB). Our aim was to review epidemiologic studies with a focus on these deficits and to use meta-(regression) analyses to summarize risk estimates.

METHODS

We systematically searched PubMed (including MEDLINE) and Embase for epidemiologic studies. Study evaluation considered four main aspects of risk of bias assessments, i.e. Selection of subjects (selection bias); Exposure variables; Outcome variables; Data analysis.

RESULTS

Of 56 identified references, 32 were used for meta-(regression) analyses. The overall pooled risk estimate for BCC comparing high/present vs. low/absent occupational solar exposure was 1.20 (95% CI 1.02-1.43); among studies without major deficits regarding data analysis, it was 1.10 (95% CI 0.91-1.33). Studies with low and high RoSB had pooled risk estimates of 0.83 (95% CI 0.73-0.93) and 1.95 (95% CI 1.42-2.67), respectively. The definitions of exposure and outcome variables were not correlated with study risk estimates. Studies with low RoSB in populations with the same latitude or lower than Germany had a pooled risk estimate of 1.01 (95% CI 0.88-1.15).

CONCLUSION

Due to the different associations between occupational solar exposure and BCC among studies with low and high RoSB, we reason that the current epidemiologic evidence base does not permit the conclusion that regular outdoor workers have an increased risk of BCC.

The GENESIS-UV study on ultraviolet radiation exposure levels in 250 occupations to foster epidemiological and legislative efforts to combat nonmelanoma skin cancer

BACKGROUND

Several hundred million of the 3 billion formally employed people worldwide are at risk from high levels of solar ultraviolet radiation (UVR). Chronic light damage to the skin can lead to nonmelanoma skin cancer (NMSC), especially when irradiation is too high and is acquired for decades. However, data with uniform metrics, high resolution over time and in-depth occupational profiles are not available.

OBJECTIVES

To build a worldwide usable matrix of UVR exposure in occupations and to show use cases for the data.

METHODS

One thousand test persons were recruited to wear electronic data logger dosimeters during their working time for 7 months each. The measurements yielded 3.7 billion data points for around 48 000 days with high-quality data capture covering more than 250 occupations and 650 activities. Scientific evaluation of the data included daily and half-hourly means, geographical transfer calculations to the world, threshold exceedance quotas, transcriptome effects, and occupational disease estimates.

RESULTS

A compendium for global use is presented. In-depth analyses and the resulting implications for research have been elaborated to directly link exposure data to effects in the human body. Interestingly, the annual irradiances of the different occupations span a wide range of values: from about 650 to 50 standard erythemal doses, with different distributions over the months. Detailed exposure data per occupation were derived, and the risk on an occupational or activity basis assuming different exposure level quotas was quantified. This showed that, for example, in temperate latitudes, all activities with a duration of > 2 h outdoors are associated with increased NMSC risk.

CONCLUSIONS

We offer our work to enable sound studies on the nature of ultraviolet-induced skin cancer, dose-response relationships, intermittency of skin exposure, and derivation of limit values. Sociological studies on prevention are now possible. Practitioners may use the findings for their daily work with employees.

Basal Cell Carcinoma: an updated review of pathogenesis and treatment options

Basal cell carcinoma (BCC) remains the most common malignancy worldwide. BCC pathogenesis is a result of the interplay between one's environment, genetics, and phenotypic factors. BCC has a low mortality but given its increasing incidence and potential to cause local destruction thus resulting in significant morbidity, it is vital for dermatologists to remain up to date with recent updates in this malignancy's pathogenesis and treatment. This article provides a comprehensive review of the pathogenesis of BCC as well as the current treatments available and clinical trials underway. We also touch upon the updated National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology in respect to BCC's recommended treatment modalities.

Non-melanoma skin cancer among ethnic German immigrants (resettler) from the former Soviet Union: a cohort study from 1990 to 2007

Background

UV radiation is a significant risk factor for non-melanoma skin cancer (NMSC). Ethnic Germans (resettlers) who immigrated to Germany from the former Soviet Union may have had a relatively high UV light exposure and thus a higher risk of developing NMSC. We compared the incidence of NMSC in a resettler cohort with the general population of the Saarland (Federal state of Germany) in relation to tumour location.

Methods

All new NMSC cases (resettler cohort and total population) between 1990 and 2007 were retrieved from the Saarland cancer registry and classified according to sex, histology, and location. The classification used for tumour location approximated the previous UV exposure. Age-standardized incidence rates (ASR) for the general population and standardized incidence ratios (SIR) for resettlers compared to the general population were calculated and modelled using Poisson regression.

Results

Sex-specific overall SIR indicated a significant increase in female resettlers (SIR 1.31 (95% CI 1.02–1.67)) which can mostly be attributed to an increased incidence of squamous cell carcinoma. The regression analysis showed that among resettlers the risk of developing tumours in UV-exposed skin areas was 2.16 (95% CI 1.35–3.45) higher compared to the general population.

Conclusions

Female resettlers have a higher risk to be diagnosed with NMSC than the general German population. Based on the observed distribution of tumour location, it is suspected that UV exposure contributed significantly to this risk.

Burden of disease induced by public overexposure to solar ultraviolet radiation (SUVR) at the national and subnational levels in Iran, 2005-2019

Estimating the burden of diseases induced by overexposure to solar ultraviolet radiation (SUVR) can help to prioritize environmental health interventions. The age-sex specific and cause-specific mortality and disability-adjusted life years (DALYs) attributable to overexposure to SUVR at the national and subnational levels in Iran, 2005-2019 were estimated. The burden of disease induced by overexposure to SUVR was quantified in four steps as follows: (1) estimating exposure to SUVR, (2) estimating total incidences and deaths of target causes, (3) assessing population attributable fractions of the target causes for the SUVR, and (4) calculating the attributable burden of disease. The attributable DALYs, deaths, age-standardized DALY rate, and age-standardized death rate at the national level were determined to be respectively 21896, 252, 42.59, and 0.56 in 2005 and were respectively changed to 28665, 377, 38.76, and 0.53 in 2019. The contributions of causes in the attributable DALYs at the national level were different by year and sex and for both sexes in 2019 were as follows: 46.15% for cataract, 20.36% for malignant skin melanoma, 16.07% for sunburn, 12.41% for squamous-cell carcinoma, and 5.01% for the other five causes. The contributions of population growth, population ageing, risk exposure, and risk-deleted DALY rate in the temporal variations of the attributable burden of disease in the country were +20.73%, +20.68%, +2.01%, and -12.51%. The highest and lowest provincial attributable age-standardized DALY rates in 2019 were observed in Fars (46.8) and Ardebil (32.7), respectively. The burden of disease induced by exposure to SUVR caused relatively low geographical inequality in health status in Iran. Due to increasing trends of the SUVR as well as the attributable burden of disease, the preventive interventions against the SUVR overexposure should be considered in the public health action plan all across the country.

National and subnational burden of disease attributable to occupational exposure to solar ultraviolet radiation (SUVR) in Iran, 2005-2019

Overexposure to solar ultraviolet radiation (SUVR) can cause skin and eye adverse effects for outdoor workers. In this study, the burden of disease induced by occupational exposure to SUVR and its spatiotemporal trend at national and sub-national levels in Iran, 2005-2019 were assessed. The attributable burden of disease was assessed using the following five datasets: (1) distribution of occupational exposure to SUVR, (2) total incidences and deaths of health outcomes of SUVR exposure, (3) population attributable fractions of the health outcomes of SUVR exposure, (4) age-gender distribution of outdoor workers, and (5) disability-adjusted life year (DALY) calculation constants. During 2005-2019, the attributable DALYs increased from 2442 to 2907 and the attributable DALY rate (per 100,000 workers) slightly decreased from 11.94 to 11.91. The share of YLL in the attributable burden of disease was in the range of 43%-46%. Out of nine causes, about 90% of the attributable burden of disease in 2019 was related to cataracts (29.9%), malignant skin melanoma (27.4%), squamous-cell carcinoma (18.6%), and sunburn (17.2%). During the study period, the attributable DALY rate in women increased by 60.95% (from 5.04 to 8.11) and in men decreased by 2.06% (from 13.03 to 12.76). The total attributable DALYs and DALY rate rose by age during 2005-2019. The contributions of population growth, risk-deleted DALY rates, exposure risk, and population age structure in temporal changes of the attributable burden of disease were 19.27%, 9.13%, -1.35%, and -14.8%, respectively. The three highest attributable DALY rates in 2019 were observed in South Khorasan (21.28), Chahar Mahal and Bakhtiari (17.42), and Kordestan (17.26), respectively. The preventive interventions against SUVR overexposure, regular screenings, and early treatments with an emphasis on occupations with continuous sun exposure and provinces with increasing attributable DALY rates should be considered in the occupational health action plan in the country.

Ultraviolet Radiation and Basal Cell Carcinoma: An Environmental Perspective

Ultraviolet radiation (UVR) is a known carcinogen participated for the development of skin cancers. Solar UVR exposure, particularly ultraviolet B (UVB), is the mostly significant environmental risk factor for the occurrence and progress of basal cell carcinoma(BCC). Both cumulative and intermittent high-grade UVR exposure could promote the uncontrolled replication of skin cells. There are also exsiting other contributing environmental factors that combine with the UVR exposure to promote the development of BCC. DNA damage in formation of skin cancers is considered to be a result of UVR toxicity. It is UVR that could activate a series of oncogenes simultaneously inactivating tumor suppressor genes and aberrant proliferation and survival of keratinocytes that repair these damages. Furthermore, mounting evidence demonstrates that inflammatory responses of immune cells in the tumor microenvironment plays crucial role in the skin tumorigenesis as well. In this chapter, we will follow the function of UVR in the onset and development of BCC. We describe the factors that influence BCC induced by UVR, and also review the recent advances of pathogenesis of BCC induced by UVR from the genetic and inflammatory aspects.

Lifetime Ambient UV Radiation Exposure and Risk of Basal Cell Carcinoma by Anatomic Site in a Nationwide U.S. Cohort, 1983-2005

BACKGROUND

Cutaneous basal cell carcinoma (BCC) has long been associated with UV radiation (UVR) exposure, but data are limited on risks by anatomic site.

METHODS

We followed 63,912 cancer-free White U.S. radiologic technologists from cohort entry (1983-1989/1994-1998) to exit (date first BCC via 2003-2005 questionnaire). We estimated associations between cumulative ambient UVR and relative/absolute risks of self-reported BCC by anatomic location via Poisson models.

RESULTS

For incident first primary BCC in 2,124 subjects (mean follow-up, 16.9 years) log[excess relative risks] (ERR) of BCC per unit cumulative ambient UVR = 1.27/MJ cm^-2 [95% confidence interval (CI): 0.86-1.68; P _trend < 0.001] did not vary by anatomic site (P = 0.153). However, excess absolute risks of BCC per unit cumulative ambient UVR were large for the head/neck = 5.46/MJ cm^-2/10⁴ person-year (95% CI: 2.92-7.36; P _trend < 0.001), smaller for the trunk (2.56; 95% CI: 1.26-3.33; P _trend = 0.003), with lesser increases elsewhere. There were lower relative risks, but higher absolute risks, for those with Gaelic ancestry (P < 0.001), also higher absolute risks among those with fair complexion, but relative and absolute risks were not generally modified by other constitutional, lifestyle or medical factors for any anatomic sites. Excess absolute and relative risk was concentrated 5-15 years before time of follow-up.

CONCLUSIONS

BCC relative and absolute risk rose with increasing cumulative ambient UVR exposure, with absolute risk highest for the head/neck, to a lesser extent in the trunk.

IMPACT

These associations should be evaluated in other White and other racial/ethnic populations along with assessment of possible modification by time outdoors, protective, and behavioral factors.

Deiodinases and Cancer

Hormones are key drivers of cancer development, and alteration of the intratumoral concentration of thyroid hormone (TH) is a common feature of many human neoplasias. Besides the systemic control of TH levels, the expression and activity of deiodinases constitute a major mechanism for the cell-autonomous, prereceptoral control of TH action. The action of deiodinases ensures tight control of TH availability at intracellular level in a time- and tissue-specific manner, and alterations in deiodinase expression are frequent in tumors. Research over the past decades has shown that in cancer cells, a complex and dynamic expression of deiodinases is orchestrated by a network of growth factors, oncogenic proteins, and miRNA. It has become increasingly evident that this fine regulation exposes cancer cells to a dynamic concentration of TH that is functional to stimulate or inhibit various cellular functions. This review summarizes recent advances in the identification of the complex interplay between deiodinases and cancer and how this family of enzymes is relevant in cancer progression. We also discuss whether deiodinase expression could represent a diagnostic tool with which to define tumor staging in cancer treatment or even a therapeutic tool against cancer.

Basal cell carcinoma risk and solar UV exposure in occupationally relevant anatomic sites: do histological subtype, tumor localization and Fitzpatrick phototype play a role? A population-based case-control study

Background

A two-fold risk increase to develop basal cell carcinoma was seen in outdoor workers exposed to high solar UV radiation compared to controls. However, there is an ongoing discussion whether histopathological subtype, tumor localization and Fitzpatrick phototype may influence the risk estimates.

Objectives

To evaluate the influence of histological subtype, tumor localization and Fitzpatrick phototype on the risk to develop basal cell carcinoma in highly UV-exposed cases and controls compared to those with moderate or low solar UV exposure.

Methods

Six hundred forty-three participants suffering from incident basal cell carcinoma in commonly sun-exposed anatomic sites (capillitium, face, lip, neck, dorsum of the hands, forearms outside, décolleté) of a population-based, case-control, multicenter study performed from 2013 to 2015 in Germany were matched to controls without skin cancer. Multivariate logistic regression analysis was conducted stratified for histological subtype, phototype 1/2 and 3/4. Dose-response curves adjusted for age, age², sex, phototype and non-occupational UV exposure were calculated.

Results

Participants with high versus no (OR 2.08; 95% CI 1.24–3.50; p = 0.006) or versus moderate (OR 2.05; 95% CI 1.15–3.65; p = 0.015) occupational UV exposure showed a more than two-fold significantly increased risk to develop BCC in commonly UV-exposed body sites. Multivariate regression analysis did not show an influence of phototype or histological subtype on risk estimates. The restriction of the analysis to BCC cases in commonly sun-exposed body sites did not influence the risk estimates. The occupational UV dosage leading to a 2-fold increased basal cell carcinoma risk was 6126 standard erythema doses.

Conclusion

The risk to develop basal cell carcinoma in highly occupationally UV-exposed skin was doubled consistently, independent of histological subtype, tumor localization and Fitzpatrick phototype.

Global evidence on occupational sun exposure and keratinocyte cancers: a systematic review

Individual studies have suggested that the association between occupational exposure to solar ultraviolet radiation (UVR) and the development of keratinocyte cancers (KCs) may only be valid in populations of European ancestry living in certain geographical regions. Comparative global data are scarce and so this review aimed to summarize current evidence on the association between occupational exposure to solar UVR and the development of KCs, with a specific focus on geographical location and skin colour. Ovid MEDLINE, PubMed, Embase and Web of Science were searched for potentially relevant records. Extracted data were summarized by study, country and region. We included one prospective cohort study and 18 case-control studies (n = 15 233) from 12 countries in regions where the majority of the population is white skinned (Americas, Europe and Oceania). Eighteen of the 19 studies reported effect estimates suggesting an increased risk of basal cell carcinoma (BCC) and/or squamous cell carcinoma (SCC) among outdoor workers. Only 11 studies found a significantly increased risk and many had imprecise estimates. There was a significantly increased risk of BCC and SCC in individual studies in North America, Latin America and the Caribbean, Western Europe and Southern Europe, but not across regions or countries. Overall, 95% of studies reported higher risks among outdoor workers, although the increases in risk were statistically significant in just over half of the studies. Well-designed and sufficiently powered occupational case-control and cohort studies with adequate adjustment for confounding factors and other risk factors are required to provide more accurate risk estimates for occupational KC.

Management of Non-melanoma Skin Cancer in Transplant Recipients

Transplant recipients have a significantly higher risk of developing non-melanoma skin cancers compared with the general population and squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) are the most common post-transplant malignancies. Although in the general population BCC outnumbers SCC 4:1, in transplant patients this ratio is reversed and SCC is more common, with a 65- to 250-fold increased incidence. As patients in immunosuppressed states are living longer after transplants, the incidence of skin cancer in this population continues to increase. The skin cancers in transplant patients also tend to be more aggressive, with higher morbidity and mortality. Preventive strategies play an important role in transplant recipients given their increased frequency of developing both premalignant and malignant skin lesions. Sun protection and regular skin cancer screening are critical. In addition, chemoprophylaxis with systemic retinoids, nicotinamide and capecitabine can significantly reduce the development of new skin cancers. Topical 5-fluorouracil, imiquimod, photodynamic therapy and cyclooxygenase inhibitors have all been investigated in transplant patients for the treatment of field cancerisation. Adjusting the immunosuppressive regimen is also an important adjuvant therapeutic strategy for managing skin cancers in transplant recipients and requires integrated multidisciplinary care with the entire transplant team. This article reviews the epidemiology of non-melanoma skin cancer in transplant patients, discusses the prevention strategies and highlights the management and treatment strategies of both field cancerisation and non-melanoma skin cancers.

Mechanics of PAK1-A new molecular player in the arena of skin cancer

Despite regular exposure of skin to solar UV-B irradiation, most individuals enjoy cancer-free existence, which is a testimony of the inherent capacity of human keratinocytes to either repair or restore cells damged by UV exposure. In this manuscript, we focus on delineating the mechanistic role of p21 activated kinase (Pak1) in UV-B provoked skin lesions. Molecular mechanistic studies revealed that Pak1 is triggered as a consequence to UV-B exposure via epidermal growth factor receptor (EGFR) and cyclobutane pyrimidine dimers (CPD) pathways, and both these membranous (EGFR) and nuclear (CPDs) events converge at Pak1 activation and contribute in a coordinated manner for yielding a complete response to UV-B via upregulating Ataxia-Telangiectasia and Rad3 related (ATR). This is the first study that evaluates the mechanistic role of a signaling molecule, Pak1, in premalignant skin lesions caused by sun exposure and designate that expression and instigation of Pak1 could operate as an alarming indicator of succession towards aggressive form of skin cancer, if neglected.

Promoting sunscreen use and skin self-examination to improve early detection and prevent skin cancer: quasi-experimental trial of an adolescent psycho-educational intervention

Background

Skin cancer rates are increasing. Interventions to increase adolescent sunscreen use and skin self-examination (SSE) are required.

Methods

Quasi-experimental design; 1 control and 4 intervention group schools in Scotland, UK. Participants were 15–16 year old students on the school register. The intervention was a theoretically-informed (Common-Sense Model and Health Action Process Approach) 50-min presentation, delivered by a skin cancer specialist nurse and young adult skin cancer survivor, to students in a classroom, supplemented by a home-based assignment. Outcome variables were sunscreen use intention, SSE intention/behaviour, planning, illness perceptions and skin cancer communication behaviour, measured 2 weeks pre- and 4 weeks post- intervention using self-completed pen and paper survey. School attendance records were used to record intervention up-take; students self-reported completion of the home-based assignment. Pearson’s chi-square test, analysis of variance, and non-parametric Wilcoxon Signed Ranks Test were used to measure outcomes and associations between variables. Focus groups elicited students’ (n = 29) views on the intervention. Qualitative data were analysed thematically.

Results

Five of 37 invited schools participated. 639 (81%) students in intervention schools received the intervention; 33.8% completed the home-based assignment. 627 (69.6%) of students on the school register in intervention and control schools completed a questionnaire at baseline; data for 455 (72.6%) students were available at baseline and follow-up. Focus groups identified four themes – personal experiences of skin cancer, distaste for sunscreen, relevance of SSE in adolescence, and skin cancer conversations. Statistically significant (p < 0.05) changes were observed for sunscreen use, SSE, planning, and talk about skin cancer in intervention schools but not the control. Significant associations were found between sunscreen use, planning and 2 illness perceptions (identity and consequence) and between SSE, planning and 3 illness perceptions (timeline, causes, control).

Conclusions

It is feasible to promote sunscreen use and SSE in the context of an adolescent school-based psychoeducation intention. Further research is required to improve study uptake, intervention adherence and effectiveness.

Trial registration

ISRCTN11141528

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5570-y) contains supplementary material, which is available to authorized users.

Risk of Basal and Squamous Cell Carcinomas of the Skin in Sion, Switzerland: A Case-control Study

Aims and Background

Non-melanocytic skin cancers are the most common cancers in white populations. Studies on populations of Anglo-Saxon and Mediterranean origins highlighted different patterns of risk of basal-cell carcinoma and squamous-cell carcinoma in relation to sunlight exposure, skin characteristics and phenotype susceptibility. In Sion, and in Switzerland as a whole, the high incidence suggests the possible presence of additional risk factors or of a different pattern of exposure to solar radiation as well as different composition of pigmentary traits and skin sensitivity to sun.

Methods and Study Design

We conducted a case-control study of 146 cases (73% of eligible cases) and 144 controls (81% of eligible subjects) to further evaluate the relationship between nonmelanocytic skin cancer and risk factors in the Sion population. Interviews were conducted by trained interviewers with a standardized questionnaire.

Results

Pigmentary characteristics such as blonde and red hair as well as tendency to sunburn without tanning and number of sunburns showed a statistically significant and independent risk increase in basal-cell carcinoma. Sun exposure during recreational activities (outdoor sports) showed a risk increase in basal-cell carcinoma with borderline statistical significance. Analysis of squamous-cell carcinoma risk was limited by the small number of cases, but it was positively associated with lifetime exposure to sun during outdoor work and with skin characteristics.

Conclusions

Results confirmed previous suggestions of a different mechanism leading to malignant transformation of target cells from the basal and squamous epidermal layers, mediated by different phenotypes, and conditioning the ability to develop an effectively protective tan.

Reproducibility of Histopathologic Diagnosis and Classification of Non-Melanocytic Skin Cancer: A Panel Exercise in the Framework of the Multicenter Southern European Study Helios

Aims and background

The reproducibility of histologic diagnoses, and in particular of the distinction between basal and squamous cell forms, has been evaluated in the framework of a multicenter case-control study (in Italy, France, Spain and Switzerland) aimed to assess the causes of non-melanocytic skin cancers.

Methods

A panel composed of 10 pathologists from the collaborating centers was appointed. A total of 1774 slides of routine diagnoses were blindly reviewed by a second panelist; discordant diagnoses underwent a third examination. Controversial and interesting cases were discussed during general sessions.

Results

The results showed a high degree of concordance (99.5%), with a Cohen's kappa of 0.85 (95% CI, 0.77–0.94) in the assessment of malignancy of lesions. The concordance in the distinction between large morphologic groups, basal cell carcinoma and squamous cell carcinoma was also high (Cohen's kappa = 0.85; 95% CI, 0.82–0.89). The assessment of histologic subtypes, degree of invasion and differentiation showed a lower degree of concordance, presumably as a consequence of a weaker consistency in the relevant classifications.

Conclusions

The reproducibility study has therefore validated the epidemiologic study and in particular allowed to correct some misclassifications that could have lessened the analysis of the case-control study. In general, because of its characteristics (number of pathologists and variety of their origins, the large number of cases examined, blind examination of histologic slides), the conclusions of the study may show a certain degree of generalization, at least with regard to the countries represented. Routine histologic diagnoses of cutaneous carcinoma showed a high degree of reliability with reference to the assessment of malignancy and the distinction between basal and squamous cell carcinoma morphotypes.

Small Molecule Inhibitors of the Hedgehog Pathway in the Treatment of Basal Cell Carcinoma of the Skin

Basal cell carcinoma (BCC) is the most common type of skin cancer, with rising incidence rates primarily attributed to an aging population and ultraviolet radiation exposure. While the majority of BCCs are localized and respond to standard therapies, a very small minority of these tumors become locally destructive or metastasize. These advanced BCCs may not be amenable to localized treatment with surgery and/or radiation therapy. Most BCCs result from mutations in key receptors in the Hedgehog (HH) signaling pathway. As a result, identification of drugs that inhibit the receptor Smoothened (SMO) in the HH pathway has resulted in novel therapeutic approaches to treating patients with advanced BCC. These HH-pathway inhibiting medications have shown efficacy in clinical trials, and two medications, vismodegib and sonidegib, have received FDA approval. However, several limitations of these drugs have been identified, including treatment-limiting adverse events, drug resistance, and the formation of additional malignancies. This paper aims to summarize the clinical trials leading to the approval of SMO inhibitors, as well as reviewing potential mechanisms driving tumor resistance and the formation of cutaneous squamous cell carcinomas. Strategies to overcome some of these challenges, including the development of drugs that inhibit other downstream targets in the HH pathway, are the subject of ongoing clinical trials.

Early Life UV and Risk of Basal and Squamous Cell Carcinoma in New South Wales, Australia

Sun exposure is the main cause of squamous (SCC) and basal cell carcinoma (BCC) although pattern and amount differ by cancer type, and sun sensitivity is the major host risk factor. Our study investigated risk factors and residential ambient UV in a population-based sample of Australian 45 and Up Study participants: 916 BCC cases, 433 SCC cases, 1224 controls. Unconditional logistic regression models adjusting for key covariates demonstrated 60% increased BCC risk and two-fold increased SCC risk with sun sensitivity, and three- and four-fold increased risk, respectively, with solar keratoses. BCC but not SCC risk increased with higher early-life residential UV in all participants (odds ratio (OR) = 1.54; 95% CI 1.22-1.96 for intermediate; OR = 1.31; 95% CI 1.03-1.68 for high UV at birthplace) and similarly in Australian-born participants (P-values < 0.05). Risk of SCC but not BCC increased with long-term cumulative sun exposure assessed by self-reported outdoor work (OR 1.74, 95% CI 1.21-2.49). In conclusion, sun sensitivity is important for both cancers, early-life UV but not cumulative UV appears to increase BCC risk, the former an apparently novel finding, and SCC risk appears only to be related to long-term cumulative sun exposure.

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.

The epidemic spreading of basal cell carcinoma: incidence trend, demographic features, characteristics and risk factors in a retrospective study of 8557 lesions in Bologna. A 25-year analysis in a Dermatology referral center

BACKGROUND

The aim of this study was to retrospectively analyze all the cases of BCC histologically diagnosed in the Cutaneous Tumor Center of Dermatology of Bologna University, in a period between 1990 and 2014.

METHODS

All the consecutive histopathologically diagnosed BCCs at the Dermatology of the Bologna University from 1990 to 2014 were retrospectively reviewed. We evaluated the absolute number of basal cell carcinoma (BCCs), the demographic features of patients and the characteristics of BCCs with statistically significant correlations.

RESULTS

During the investigated 25 years, 8557 BCCs were collected in 7297 patients. We observed that the incidence of this cancer, after stabilizing around a plateau of 400 cases/year in 2005, progressively increased onwards reaching a maximum of cases (821) in 2014 (+105.25%), with an 8.32% mean increase per year in those last 9 years. Moreover, we found a significant correlation (P<0.01%) between gender and the onset of BCC, between the anatomic location and the occurrence of the tumor, between the onset of recurrent or new BCCs and sun exposure.

CONCLUSIONS

The present study collects the largest series in the Italian literature focused on demographic features and characteristics of BCC, highlights its higher increasing incidence in Bologna and the need to improve preventive strategies to stem the epidemic diagnosis of BCC.

Non-melanoma skin cancer: new and future synthetic drug treatments

INTRODUCTION

Non-melanoma skin cancers (NMSC) mainly comprise two different entities: basal cell carcinoma (BCC) and squamous cell carcinoma (SCC); beneath these two entities, Merkel cell carcinoma, adnexal tumors, dermatofibrosarcoma protuberans, angiosarcoma, and cutaneous lymphoma belong to NMSC. These rare skin tumors are not the topic of this review. BCC and SCC are the most common cancers diagnosed in humans. The preferred treatment is surgery, which in most cases is curative. Although a high recurrence rate is seen, these cancers rarely metastasize. Therefore, systemic treatments were not a priority for these patients. It is long known that the abnormal activation of Hedgehog and epidermal growth factor receptor pathways were involved in BCC and SCC. In the last decade, metastatic disease became an important area of research, mostly because new therapies that targeted components of these two pathways became available. Areas covered: Here we cover the available therapeutic options for patients diagnosed with BCC and SCC, focus on systemic and targeted therapies. Expert opinion: BCC and SCC are common cancers, with good prognosis. More than the metastatic disease, advanced local disease and recurrent disease pose clinicians a great challenge. Albeit there are promising results with targeted therapies, resistance development has already been described.

Sonidegib, a novel smoothened inhibitor for the treatment of advanced basal cell carcinoma

Basal cell carcinoma (BCC) is the most common nonmelanoma skin cancer. If left untreated, BCCs can become locally aggressive or even metastasize. Currently available treatments include local destruction, surgery, and radiation. Systemic options for advanced disease are limited. The Hedgehog (Hh) pathway is aberrantly activated in a majority of BCCs and in other cancers. Hh pathway inhibitors are targeted agents that inhibit the aberrant activation of the Hh pathway, with smoothened being a targeted component. Sonidegib is a novel smoothened inhibitor that was recently approved by the US Food and Drug Administration. This review focuses on BCC pathogenesis and the clinical efficacy of sonidegib for the treatment of advanced BCC.

Gene Expression and Proteome Analysis as Sources of Biomarkers in Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the world's leading skin cancer in terms of frequency at the moment and its incidence continues to rise each year, leading to profound negative psychosocial and economic consequences. UV exposure is the most important environmental factor in the development of BCC in genetically predisposed individuals, this being reflected by the anatomical distribution of lesions mainly on sun-exposed skin areas. Early diagnosis and prompt management are of crucial importance in order to prevent local tissue destruction and subsequent disfigurement. Although various noninvasive or minimal invasive techniques have demonstrated their utility in increasing diagnostic accuracy of BCC and progress has been made in its treatment options, recurrent, aggressive, and metastatic variants of BCC still pose significant challenge for the healthcare system. Analysis of gene expression and proteomic profiling of tumor cells and of tumoral microenvironment in various tissues strongly suggests that certain molecules involved in skin cancer pathogenic pathways might represent novel predictive and prognostic biomarkers in BCC.

Estimation of individual cumulative ultraviolet exposure using a geographically-adjusted, openly-accessible tool

Background

Estimates of an individual’s cumulative ultraviolet (UV) radiation exposure can be useful since ultraviolet radiation exposure increases skin cancer risk, but a comprehensive tool that is practical for use in the clinic does not currently exist.

The objective of this study is to develop a geographically-adjusted tool to systematically estimate an individual’s self-reported cumulative UV radiation exposure, investigate the association of these estimates with skin cancer diagnosis, and assess test reliability.

Methods

A 12-item online questionnaire from validated survey items for UV exposure and skin cancer was administered to online volunteers across the United States and results cross-referenced with UV radiation indices. Cumulative UV exposure scores (CUES) were calculated and correlated with personal history of skin cancer in a case–control design. Reliability was assessed in a separate convenience sample.

Results

1,118 responses were included in the overall sample; the mean age of respondents was 46 (standard deviation 15, range 18 – 81) and 150 (13 %) reported a history of skin cancer. In bivariate analysis of 1:2 age-matched cases (n = 149) and controls (n = 298), skin cancer cases were associated with (1) greater CUES prior to first skin cancer diagnosis than controls without skin cancer history (242,074 vs. 205,379, p = 0.003) and (2) less engagement in UV protective behaviors (p < 0.01). In a multivariate analysis of age-matched data, individuals with CUES in the lowest quartile were less likely to develop skin cancer compared to those in the highest quartile. In reliability testing among 19 volunteers, the 2-week intra-class correlation coefficient for CUES was 0.94. We have provided the programming code for this tool as well as the tool itself via open access.

Conclusions

CUES is a useable and comprehensive tool to better estimate lifetime ultraviolet exposure, so that individuals with higher levels of exposure may be identified for counseling on photo-protective measures.

Electronic supplementary material

The online version of this article (doi:10.1186/s12895-016-0038-1) contains supplementary material, which is available to authorized users.

Advanced basal cell carcinoma, the hedgehog pathway, and treatment options - role of smoothened inhibitors

Cutaneous basal cell carcinoma (BCC) is the most common human cancer and its incidence is rising worldwide. Ultraviolet radiation exposure, including tanning bed use, as well as host factors play a role in its development. The majority of cases are treated and cured with local therapies including surgery. Yet, the health care costs of diagnosis and treatment of BCCs in the US is substantial. In the United States, the cost of nonmelanoma skin cancer care in the Medicare population is estimated to be US$426 million per year. While rare, locally advanced BCCs that can no longer be controlled with surgery and/or radiation, and metastatic BCCs do occur and can be associated with significant morbidity and mortality. Vismodegib (GDC-0449), a smoothened inhibitor targeted at the hedgehog pathway, is the first US Food and Drug Association (FDA)-approved agent in the treatment of locally advanced, unresectable, and metastatic BCCs. This class of agents appears to be changing the survival rates in advanced BCC patients, but appropriate patient selection and monitoring are important. Multidisciplinary assessments are essential for the optimal care and management of these patients. For some patients with locally advanced BCC, treatment with a hedgehog inhibitor may eliminate the need for an excessively disfiguring or morbid surgery.

Extra-intestinal malignancies in inflammatory bowel disease: results of the 3rd ECCO Pathogenesis Scientific Workshop (III)

The incidence of lymphoproliferative disorders (LD) is increasing in developed countries. Patients with inflammatory bowel disease (IBD) exposed to thiopurines are at additional risk of three specific forms of LD: Epstein-Barr-Virus-related post-transplant like LD, hepato-splenic T-cell lymphoma and post-mononucleosis lymphoproliferation. The risk of the two latter forms of LD can be reduced when considering specific immunosuppressive strategies in young males. It is still unclear whether the risk of uterine cervix abnormalities is increased in IBD women, irrespective of the use of immunosuppressants. Given the excess risk demonstrated in various other contexts of immunosuppression, it is currently recommended that all women with IBD, particularly those receiving immunosuppressants, strictly adhere to a screening program of cervical surveillance and undergo vaccination against HPV, when appropriate. Patients with IBD receiving immunosuppressants are at increased risk of skin cancers. The risk of non-melanoma skin cancer is notably increased in patients receiving thiopurines. Recent data suggest that the risk of melanoma is mildly increased in patients exposed to anti-TNF therapy. All IBD patients should adhere to a program of sun protection and dermatological surveillance, whose details should take into account the other non-IBD-related risk factors.

MC1R gene variants and sporadic malignant melanoma susceptibility in the Canary Islands population

Several MC1R variants are associated with increased risk of malignant melanoma (MM) in a variety of populations. We aim to examine the influence of the MC1R variants (RHC: D84E, R151C, R160W; NRHC: V60L, R163Q and the synonymous polymorphism T314T) on the MM risk in a population from the Canary Islands. Overall, 1,046 Caucasian individuals were included in the study. A thousand of them were genotyped for MC1R variants: 509 were sporadic MM patients and 491 were healthy control subjects from general population. The analysis was adjusted for age, sex, hair colour, eye colour, skin phototype and ancestry. We found that carriers of the R151C and R163Q variants were at an increased risk for melanoma OR 2.76 (1.59-4.78) and OR 5.62 (2.54-12.42), respectively. The risk of carrying RHC variants was 3.04 (1.90-4.86). Current study confirms the increased MM risk for R151C carriers. It also supports the association between R163Q variant and MM risk in the population on the Canary Islands, as opposed to reported on northern populations. These results highlight the importance of the sample population selection in this kind of studies.

Patterns and timing of sunlight exposure and risk of basal cell and squamous cell carcinomas of the skin--a case-control study

BACKGROUND

Non-melanoma skin cancer (NMSC), comprised of basal (BCC) and squamous (SCC) cell carcinomas, is the most common cancer in Caucasians. Ultraviolet radiation (UVR) exposure is the most important environmental risk factor for NMSC. However, the precise relationship between UVR and the risk of NMSC is complex, and the relationship may differ by skin cancer type.

METHODS

A case-control study was conducted among Florida residents to investigate measures of patterns (intermittent vs. continuous) and timing (childhood vs. adulthood) of sunlight exposure in BCC and SCC. Participants included 218 BCC and 169 SCC cases recruited from a university dermatology clinic and 316 controls with no history of skin or other cancers.

RESULTS

A history of blistering sunburn (a measure of intermittent sunlight exposure) was associated with both BCC (OR = 1.96, 95% CI = 1.27-3.03) and SCC (OR = 2.02, 95% CI = 1.22-3.33). Additionally, having a job in the sun for ≥ 3 months for 10 years or longer (a measure of continuous sunlight exposure) was also associated with both BCC and SCC in our study population. With the exception of younger age at first blistering sunburn, measures of younger age at sunlight exposure tended to be associated with SCC, but not BCC risk.

CONCLUSIONS

Results from the current study suggest that sunlight exposure is associated with both BCC and SCC risk regardless of the pattern in which the exposure was received (i.e. intermittent vs. continuous). The data also suggest that sunlight exposure at a younger age may be more important for SCC but not BCC, however additional studies are needed to further characterize sunlight exposure-response relationships in different types of NMSC.

Assessing the impacts of lifetime sun exposure on skin damage and skin aging using a non-invasive method

BACKGROUND

Ultraviolet radiation exposure during an individuals' lifetime is a known risk factor for the development of skin cancer. However, less evidence is available on assessing the relationship between lifetime sun exposure and skin damage and skin aging.

OBJECTIVES

This study aims to assess the relationship between lifetime sun exposure and skin damage and skin aging using a non-invasive measure of exposure.

METHODS

We recruited 180 participants (73 males, 107 females) aged 18-83 years. Digital imaging of skin hyperpigmentation (skin damage) and skin wrinkling (skin aging) on the facial region was measured. Lifetime sun exposure (presented as hours) was calculated from the participants' age multiplied by the estimated annual time outdoors for each year of life. We analyzed the effects of lifetime sun exposure on skin damage and skin aging. We adjust for the influence of age, sex, occupation, history of skin cancer, eye color, hair color, and skin color.

RESULTS

There were non-linear relationships between lifetime sun exposure and skin damage and skin aging. Younger participant's skin is much more sensitive to sun exposure than those who were over 50 years of age. As such, there were negative interactions between lifetime sun exposure and age. Age had linear effects on skin damage and skin aging.

CONCLUSION

The data presented showed that self reported lifetime sun exposure was positively associated with skin damage and skin aging, in particular, the younger people. Future health promotion for sun exposure needs to pay attention to this group for skin cancer prevention messaging.

The challenges of UV-induced immunomodulation for children's health

Exposure to solar ultraviolet radiation (UVR) is recognised to have both beneficial and harmful effects on human health. With regard to immune responses, it can lead to suppression of immunity and to the synthesis of vitamin D, a hormone that can alter both innate and adaptive immunity. The consequences in children of such UV-induced changes are considerable: first there are positive outcomes including protection against some photoallergic (for example polymorphic light eruption) and T cell-mediated autoimmune diseases (for example multiple sclerosis) and asthma, and secondly there are negative outcomes including an increased risk of skin cancer (squamous cell carcinoma, basal cell carcinoma and cutaneous malignant melanoma) and less effective control of several infectious diseases. Many uncertainties remain regarding the amount of sun exposure that would provide children with the most effective responses against the variety of immunological challenges that they are likely to experience.

Targeted therapy in nonmelanoma skin cancers

Nonmelanoma skin cancer (NMSC) is the most prevalent cancer in light-skinned populations, and includes mainly Basal Cell Carcinomas (BCC), representing around 75% of NMSC and Squamous Cell Carcinomas (SCC). The incidence of these tumors is continuously growing. It was found that the overall number of procedures for NMSC in US rose by 76%, from 1,158,298 in 1992 to 2,048,517 in 2006. Although mortality from NMSC tends to be very low, clearly the morbidity related to these skin cancers is very high. Treatment options for NMSC include both surgical and nonsurgical interventions. Surgery was considered the gold standard therapy, however, advancements in the knowledge of pathogenic mechanisms of NMSCs led to the identification of key targets for drug intervention and to the consequent development of several targeted therapies. These represent the future in treatment of these common forms of cancer ensuring a high cure rate, preservation of the maximal amount of normal surrounding tissue and optimal cosmetic outcome. Here, we will review recent advancements in NMSC targeted therapies focusing on BCC and SCC.

Non-melanoma skin cancer

The rising incidence and morbidity of non-melanoma skin cancers has generated great interest in unravelling of their pathogenesis and in the search for new non-invasive treatments. Whereas the role of cumulative sun exposure in pathogenesis of squamous-cell carcinoma seems clear, the relation between sun-exposure patterns and subtypes of basal-cell carcinoma remains undetermined. Several complex genotypic, phenotypic, and environmental factors contribute to pathogenesis of non-melanoma skin cancers. Unlike basal-cell carcinoma, squamous-cell carcinomas can arise from precursor lesions. Diagnosis of non-melanoma skin cancer is made clinically and confirmed by histological testing. Prognosis depends on lesion and host characteristics, which also dictate choice of treatment. Prevention strategies aim at reduction of sun exposure, but are of unproven benefit, especially for basal-cell carcinoma. Surgical excision with predetermined margins is the mainstay of treatment for squamous-cell carcinoma and for most basal-cell carcinomas. Of the new non-invasive treatments, only photodynamic therapy and topical imiquimod have become established treatments for specific subtypes of basal-cell carcinoma, and the search for more effective and tissue-salvaging therapies continues.

Population-based, case-control-family design to investigate genetic and environmental influences on melanoma risk: Australian Melanoma Family Study

Discovering and understanding genetic risk factors for melanoma and their interactions with phenotype, sun exposure, and other risk factors could lead to new strategies for melanoma control. This paper describes the Australian Melanoma Family Study, which uses a multicenter, population-based, case-control-family design. From 2001 to 2005, the authors recruited 1,164 probands including 629 cases with histopathologically confirmed, first-primary cutaneous melanoma diagnosed before age 40 years, 240 population-based controls frequency matched for age, and 295 spouse/friend controls. Information on lifetime sun exposure, phenotype, and residence history was collected for probands and nearly 4,000 living relatives. More than 3,000 subjects donated a blood sample. Proxy-reported information was collected for childhood sun exposure and deceased relatives. Important features of this study include the population-based, family-based design; a focus on early onset disease; probands from 3 major cities differing substantially in solar ultraviolet exposure and melanoma incidence; a population at high risk because of high ultraviolet exposure and susceptible pigmentation phenotypes; population-based, spouse/friend, and sibling controls; systematic recruitment of relatives of case and control probands; self and parent reports of childhood sun exposure; and objective clinical skin examinations. The authors discuss methodological and analytical issues related to the study design and conduct, as well as the potentially novel insights the study can deliver.

Spatiotemporal and Spatial Threshold Models for Relating UV Exposures and Skin Cancer in the Central United States

The exact mechanisms relating exposure to ultraviolet (UV) radiation and elevated risk of skin cancer remain the subject of debate. For example, there is disagreement on whether the main risk factor is duration of the exposure, its intensity, or some combination of both. There is also uncertainty regarding the form of the dose-response curve, with many authors believing only exposures exceeding a given (but unknown) threshold are important. In this paper we explore methods to estimate such thresholds using hierarchical spatial logistic models based on a sample of a cohort of x-ray technologists for whom we have self-reports of time spent in the sun and numbers of blistering sunburns in childhood. A preliminary goal is to explore the temporal pattern of UV exposure and its gradient. Changes here would imply that identical exposure self-reports from different calendar years may correspond to differing cancer risks.

Patients with both basal and squamous cell carcinomas are at a lower risk of further basal cell carcinomas than patients with only a basal cell carcinoma

BACKGROUND

The rate of development of further basal cell carcinoma (BCC) after first presentation is highly variable. The mechanisms that determine this phenotypic difference are unclear.

OBJECTIVE

We assessed the risks of developing a subsequent BCC in patients who developed a BCC and a squamous cell carcinoma (SCC) and compared them with patients who developed a BCC only.

METHODS

In all, 1040 patients who developed BCC only were compared with 140 patients who developed BCC and SCC to see whether the latter group included a high proportion of risk phenotypes (eg, male sex and fair skin). We then compared the number of BCCs developing per year in the two groups (174 BCC only and 71 BCC/SCC) during a 5-year period after initial BCC presentation.

RESULTS

The BCC/SCC group demonstrated a significantly lower BCC/year rate than BCC only group. The rate of development of further BCC during 5-year follow-up was lower in the BCC/SCC group because a smaller number of patients developed subsequent BCC and not because the same proportion of patients developed lesions but in smaller numbers. After 5 years of follow-up, 51.1% of BCC and 74.6% of BCC/SCC cases were free from a subsequent BCC. Logistic regression analysis corrected for age at initial presentation confirmed that patients with BCC/SCC were less likely to develop a further BCC during the 5 years after initial presentation (P = .001, odds ratio = 0.31, 95% confidence interval 0.15-0.63).

LIMITATIONS

Because of the large patient group and long study follow-up from the date of the index BCC or SCC, not all data were obtained. Where this is the case, the number of patients for whom the information is available is provided.

CONCLUSIONS

Patients who develop a BCC are similar to patients who develop both a BCC and SCC, confirming the overlap of causative factors. Patients who develop both a BCC and SCC are less likely to develop BCCs compared with patients who develop BCC only.