Squamous Cell and Basal Cell Carcinoma of the Skin in Relation to Radiation Therapy and Potential Modification of Risk by Sun Exposure

Emerging role of mesenchymal stem cell-derived exosome microRNA in radiation injury

PURPOSE

Radiation injury (RI) is a common occurrence in malignant tumors patients receiving radiation therapy. While killing tumor cells, normal tissue surrounding the target area is inevitably irradiated at a certain dose, which can cause varying results of radiation injury. Currently, there are limited clinical treatments available for radiation injuries. In recent years, the negative effects of stem cell therapy have been reported more clearly and non-cellular therapies such as exosomes have become a focus of attention for researchers. As a type of vesicle-like substances secreted by mesenchymal stem cells (MSC), MSC derived exosomes (MSC-exo) carry DNA, mRNA, microRNA (miRNAs), specific proteins, lipids, and other active substances involved in intercellular information exchange. miRNAs released by MSC-exo are capable of alleviating and repairing damaged tissues through anti-apoptosis, modulating immune response, regulating inflammatory response and promoting angiogenesis, which indicates that MSC-exo miRNAs have great potential for application in the prevention and treatment of radiation injury. Therefore, it is necessary to explore the underlying therapeutic mechanisms of MSC-exo miRNAs in this process, which may shed new lights on the treatment of radiation injury.

CONCLUSIONS

Increasing evidence confirms that MSC-exo has shown encouraging applications in tissue repair due to the anti-apoptotic, immunoreactive, and pro-angiogenesis effects of the miRNAs it carries as intercellular communication carriers. However, miRNA-based therapeutics are still in their infancy and many practical issues remain to be addressed for clinical applications.

Predictive factors of sun protection behaviour among global airline pilots

BACKGROUND

Airline pilots face significant ultraviolet radiation exposure resulting in an increased risk of sun damage and skin cancers. We aimed to evaluate sun-protective practices and associated factors among airline pilots.

METHODS

We disseminated an online questionnaire evaluating the use of sunscreen, sunglasses, hats and protective clothing during daytime hours in the cockpit and during outdoor activities to 346 global commercial airline pilots, and we received 220 completed responses. The Pearson chi-squared test or Fisher's exact test where necessary were used to determine possible factors associated with the use of sun-protective practices. Potential confounders were adjusted for using multivariate analyses.

RESULTS

The most common sun protective behaviour was the wearing of sunglasses during daytime flights (89.5%), followed by the use of caps during outdoor activities (47.7%). More pilots applied sunscreen during daytime flights (14.1%) compared with walk-arounds (8.2%). Males were less likely to use sunscreen during flights (adjusted odds ratio, aOR = 0.76), use sunscreen for walk-arounds (aOR = 0.175) and wear long sleeves (aOR = 0.013). Pilots who flew less than 30 h a month in high latitude regions were less likely to use a cap or hat outdoors (aOR = 0.419) or use sunscreen during walk-arounds (aOR = 0.241). Younger pilots were also less likely to use caps or hats outdoors (aOR = 0.446).

CONCLUSION

Male pilots and those who spent less time in high latitudes were less likely to practice sun protection. Targeted educational efforts may be implemented to reduce occupational ultraviolet exposure.

Therapeutic implications of exosomes in the treatment of radiation injury

Radiotherapy is one of the main cancer treatments, but it may damage normal tissue and cause various side effects. At present, radioprotective agents used in clinics have side effects such as nausea, vomiting, diarrhea and hypotension, which limit their clinical application. It has been found that exosomes play an indispensable role in radiation injury. Exosomes are lipid bilayer vesicles that carry various bioactive substances, such as proteins, lipids and microRNA (miRNA), that play a key role in cell-to-cell communication and affect tissue injury and repair. In addition, studies have shown that radiation can increase the uptake of exosomes in cells and affect the composition and secretion of exosomes. Here, we review the existing studies and discuss the effects of radiation on exosomes and the role of exosomes in radiation injury, aiming to provide new insights for the treatment of radiation injury.

Non-Melanoma Skin Cancer in People Living With HIV: From Epidemiology to Clinical Management

Skin cancers represent the most common human tumors with a worldwide increasing incidence. They can be divided into melanoma and non-melanoma skin cancers (NMSCs). NMSCs include mainly squamous cell (SCC) and basal cell carcinoma (BCC) with the latest representing the 80% of the diagnosed NMSCs. The pathogenesis of NMSCs is clearly multifactorial. A growing body of literature underlies a crucial correlation between skin cancer, chronic inflammation and immunodeficiency. Intensity and duration of immunodeficiency plays an important role. In immunocompromised patients the incidence of more malignant forms or the development of multiple tumors seems to be higher than among immunocompetent patients. With regards to people living with HIV (PLWH), since the advent of combined antiretroviral therapy (cART), the incidence of non-AIDS-defining cancers (NADCs), such as NMSCs, have been increasing and now these neoplasms represent a leading cause of illness in this particular population. PLWH with NMSCs tend to be younger, to have a higher risk of local recurrence and to have an overall poorer outcome. NMSCs show an indolent clinical course if diagnosed and treated in an early stage. BCC rarely metastasizes, while SCC presents a 4% annual incidence of metastasis. Nevertheless, metastatic forms lead to poor patient outcome. NMSCs are often treated with full thickness treatments (surgical excision, Mohs micro-graphic surgery and radiotherapy) or superficial ablative techniques (such as cryotherapy, electrodesiccation and curettage). Advances in genetic landscape understanding of NMSCs have favored the establishment of novel therapeutic strategies. Concerning the therapeutic evaluation of PLWH, it’s mandatory to evaluate the risk of interactions between cART and other treatments, particularly antiblastic chemotherapy, targeted therapy and immunotherapy. Development of further treatment options for NMSCs in PLWH seems needed. We reviewed the literature after searching for clinical trials, case series, clinical cases and available databases in Embase and Pubmed. We review the incidence of NMSCs among PLWH, focusing our attention on any differences in clinicopathological features of BCC and SCC between PLWH and HIV negative persons, as well as on any differences in efficacy and safety of treatments and response to immunomodulators and finally on any differences in rates of metastatic disease and outcomes.

The role of radiation therapy in the management of cutaneous malignancies. Part I: Diagnostic modalities and applications

Radiation therapy offers distinct advantages over other currently available treatments for cutaneous malignancies in certain circumstances. Dermatologists and dermatologic surgeons should be familiar with the available radiation therapy techniques as well as their value and potential limitations in a variety of clinical scenarios. The first article in this 2-part continuing medical education series highlights the mechanisms, modalities, and applications of the most commonly used radiotherapy treatments as they relate to cutaneous oncology. We review the current indications for the use of radiation in the treatment of various cutaneous malignancies, the techniques commonly employed in modern radiotherapy, and the associated complications.

Pathogenesis of Keratinocyte Carcinomas and the Therapeutic Potential of Medicinal Plants and Phytochemicals

Keratinocyte carcinoma (KC) is a form of skin cancer that develops in keratinocytes, which are the predominant cells present in the epidermis layer of the skin. Keratinocyte carcinoma comprises two sub-types, namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). This review provides a holistic literature assessment of the origin, diagnosis methods, contributing factors, and current topical treatments of KC. Additionally, it explores the increase in KC cases that occurred globally over the past ten years. One of the principal concepts highlighted in this article is the adverse effects linked to conventional treatment methods of KC and how novel treatment strategies that combine phytochemistry and transdermal drug delivery systems offer an alternative approach for treatment. However, more in vitro and in vivo studies are required to fully assess the efficacy, mechanism of action, and safety profile of these phytochemical based transdermal chemotherapeutics.

Adherence to the National Comprehensive Cancer Network Criteria of Complete Circumferential Peripheral and Deep Margin Assessment in Treatment of High-Risk Basal and Squamous Cell Carcinoma

BACKGROUND

The National Comprehensive Cancer Network (NCCN) has established guidelines for the treatment of keratinocyte carcinomas (KCs). Complete circumferential peripheral and deep margin assessment (CCPDMA) is recommended for "high-risk" tumors that cannot be closed primarily. If flap or grafts are needed and CCPDMA was not used, it is recommended that reconstruction be delayed until achieving clear margins.

OBJECTIVE

To measure provider utilization rates of the NCCN guidelines for high-risk KCs and assess barriers that are limiting adherence.

MATERIALS AND METHODS

A ten-item questionnaire was distributed to NCCN nonmelanoma skin cancer panel members and physicians participating in KC treatment at academic institutions.

RESULTS

Response rate was 49% (57/116). Responses were categorized by practice area: Mohs surgery, pathology, and other specialties: General Dermatology, Otolaryngology, Plastic Surgery, Surgical Oncology, Radiation Oncology, and Oral and Maxillofacial Surgery. Mohs surgeons were most likely to use CCPDMA for tumors meeting NCCN criteria with 14/15 using this technique in a majority of their cases, versus 2/6 pathologists and 10/16 specialists from other fields. Reasons cited for not using CCPDMA included deference to pathologists to determine the appropriate method for margin assessment and logistical difficulty.

CONCLUSION

Further efforts are needed to increase adherence to NCCN's guidelines regarding CCPDMA in KCs.

Nonmelanoma Skin Cancer in Childhood and Young Adult Cancer Survivors Previously Treated With Radiotherapy

BACKGROUND

Radiotherapy (RT) is a risk factor for nonmelanoma skin cancer (NMSC), specifically basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), but whether features, histology, or recurrence of NMSC after RT resemble those observed in the general population is unknown.

METHODS

A retrospective review (1994-2017) was performed within the Adult Long-Term Follow-Up Program and Dermatology Service at Memorial Sloan Kettering Cancer Center. Demographics, clinical features, histology, treatment, and recurrence were collected for this patient cohort that was under close medical surveillance. Pathology images were reviewed when available.

RESULTS

A total of 946 survivors (mean age, 40 years [SD, 13]) were assessed for NMSC. The mean age at first cancer diagnosis was 16 years (range, 0-40 years [11]), and the most common diagnosis was Hodgkin lymphoma (34%; n=318). In 63 survivors, 281 primary in-field lesions occurred, of which 273 (97%) were BCC and 8 (3%) were SCC. Mean intervals from time of RT to BCC and SCC diagnosis were 24 years (range, 2-44 years) and 32 years (range, 14-46 years), respectively. The most common clinical presentation of BCC was macule (47%; n=67), and the most common histologic subtypes were superficial for BCC (48%; n=131) and in situ for SCC (55%; n=5). Mohs surgery predominated therapeutically (42%; n=117), the mean duration of follow-up after treatment was 6 years (range, 12 days-23 years), and the 5-year recurrence rate was 1% (n=1).

CONCLUSIONS

Most NMSCs arising in sites of prior RT were of low-risk subtypes. Recurrence was similar to that observed in the general population. Current guidelines recommend surgical intervention for tumors arising in sites of prior RT because they are considered to be at high risk for recurrence. These findings suggest that an expanded role for less aggressive therapy may be appropriate, but further research is needed.

Long-Term Risk of Skin Cancer Among Childhood Cancer Survivors: A DCOG-LATER Cohort Study

BACKGROUND

Skin cancer is common after radiotherapy among childhood cancer survivors (CCSs). We studied risks and risk factors for subsequent skin cancers, with emphasis on radiation dose, exposed skin surface area, and chemotherapeutic agents.

METHODS

The DCOG-LATER cohort study includes 5-year Dutch CCSs diagnosed 1963-2001. Subsequent skin cancers were identified from record linkages with the Netherlands Cancer Registry and Dutch Pathology Registry. Incidence rates were compared with general population rates. Multivariable Cox regression models were used, applying a novel method of case-control sampling enabling use of tumor location in cohort analyses. All statistical tests were two-sided.

RESULTS

Among 5843 CCSs, 259 developed 1061 basal cell carcinomas (BCCs) (standardized incidence ratio [SIR] = 29.8, 95% confidence interval [CI] = 26.3 to 33.6; excess absolute risk per 10 000 person-years (EAR) = 24.6), 20 had melanoma (SIR = 2.3, 95% CI = 1.4 to 3.5; EAR = 1.1), and 10 had squamous cell carcinoma (SIR = 7.5, 95% CI = 3.6 to 13.8; EAR = 0.8). Cumulative incidence of BCC 40 years after childhood cancer was 19.1% (95% CI = 16.6 to 21.8%) after radiotherapy vs 0.6% expected based on general population rates. After a first BCC, 46.7% had more BCCs later. BCC risk was associated with any radiotherapy to the skin compartment of interest (hazard ratio [HR] = 14.32, 95% CI = 10.10 to 20.29) and with estimated percentage in-field skin surface area (26-75%: HR = 1.99, 95% CI = 1.24 to 3.20; 76-100%: HR = 2.16, 95% CI = 1.33 to 3.53, vs 1-25% exposed; Ptrend among exposed = .002), but not with prescribed radiation dose and likelihood of sun-exposed skin-area. Of all chemotherapy groups examined, only vinca alkaloids increased BCC risk (HR = 1.54, 95% CI = 1.04 to 2.27).

CONCLUSION

CCSs have a strongly, 30-fold increased BCC risk. BCC risk appears to increase with increasing skin surface area exposed. This knowledge underscores the need for awareness by survivors and their health care providers.

Basal cell carcinoma: Epidemiology; pathophysiology; clinical and histological subtypes; and disease associations

As the most common human cancer worldwide and continuing to increase in incidence, basal cell carcinoma is associated with significant morbidity and cost. Continued advances in research have refined both our insight and approach to this seemingly ubiquitous disease. This 2-part continuing medical education article will provide a comprehensive and contemporary review of basal cell carcinoma. The first article in this series describes our current understanding of this disease regarding epidemiology, cost, clinical and histopathologic presentations, carcinogenesis, natural history, and disease associations.

Updates on the Management of Non-Melanoma Skin Cancer (NMSC)

Non-melanoma skin cancers (NMSCs) are the most common malignancy worldwide, of which 99% are basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) of skin. NMSCs are generally considered a curable diseases, yet they currently pose an increasing global healthcare problem due to rising incidence. This has led to a shift in emphasis on prevention of NMSCs with development of various skin cancer prevention programs worldwide. This article aims to summarize the most recent changes and advances made in NMSC management with a focus on prevention, screening, diagnosis, and staging.

Skin Cancers in Organ Transplant Recipients

Long-term utilization of immunosuppression in organ transplant recipients (OTRs) leads to decreased immune-mediated tumor surveillance and development of malignant tumors. A delicate balance needs to be maintained in the intensity of immunosuppression to keep the risk of malignancy low without jeopardizing life-saving graft function. OTRs are prone to developing skin cancers that exhibit unique epidemiologic, pathophysiologic, and prognostic characteristics. In this review, we discuss the most commonly reported skin cancers in OTRs: squamous cell carcinoma (SCC), basal cell carcinoma (BCC), Kaposi sarcoma, Merkel cell carcinoma, and malignant melanoma (MM). Tumors in this high-risk population are aggressive and may respond poorly to standard therapies; however, new targeted therapies are promising. Checkpoint inhibitor antibodies have been used for treatment of cutaneous SCC, Merkel cell carcinoma, and MM; epidermal growth factor receptor inhibitors have been used for cutaneous SCC; hedgehog pathway inhibitors have been used for BCC; and BRAF and MEK inhibitors are being used increasingly in the management of MM. Guidelines for dermatologic screening are variable and primarily based on expert opinion. Prospective evidence-based trials by multidisciplinary groups are needed to better define surveillance schedules for pre- and posttransplant cutaneous malignancies.

Incidence of cancer among licenced commercial pilots flying North Atlantic routes

BACKGROUND

To evaluate cancer incidence among licenced commercial pilots in association with cosmic radiation.

METHODS

Cohort study where ionizing radiation dose of cosmic radiation was estimated from airline data and software program and cancer incidence was obtained by record linkage with nation-wide cancer registry. All licenced commercial male airline pilots were followed from 1955 to 2015, ever or never employed at airline with international routes. Standardized incidence ratios were calculated and relative risk by Poisson regression, to examine exposure-response relation.

RESULTS

Eighty three cancers were registered compared with 92 expected; standardized incidence ratios were 0.90 (95% CI 0.71 to 1.11) for all cancers, 3.31 (95% CI 1.33 to 6.81) for malignant melanoma, and 2.49 (95% CI 1.69 to 3.54), for basal cell carcinoma of skin. The risk for all cancers, malignant melanoma, prostate cancer, basal cell carcinoma of skin, and basal cell carcinoma of trunk increased with an increase in number of employment years, cumulative air hours, total cumulative radiation dose, and cumulative radiation dose sustained up to age of 40 years. The relative risk for the highest exposure categories of cumulative radiation dose were 2.42 (95% CI 1.50 to 3.92) for all cancers, 2.57 (95% CI 1.18 to 5.56) for prostate cancer, 9.88 (95% CI 1.57 to 190.78) for malignant melanoma, 3.61 (95% CI 1.64 to 8.48) for all basal cell carcinoma, and 6.65 (95% CI 1.61 to 44.64) for basal cell carcinoma of trunk.

CONCLUSIONS

This study was underpowered to study brain cancer and leukaemia risk. Basal cell carcinoma of skin is radiation-related cancer, and may be attributed to cosmic radiation. Further studies are needed to clarify the risk of cancers in association with cosmic radiation, other workplace exposure, host factors, and leisure sun-exposure, as clothes, and glass in cockpit windows shield pilots from the most potent ultraviolet-radiation.

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.

A programme of research to set priorities and reduce uncertainties for the prevention and treatment of skin disease

Background

Skin diseases are very common and can have a large impact on the quality of life of patients and caregivers. This programme addressed four diseases: (1) eczema, (2) vitiligo, (3) squamous cell skin cancer (SCC) and (4) pyoderma gangrenosum (PG).

Objective

To set priorities and reduce uncertainties for the treatment and prevention of skin disease in our four chosen diseases.

Design

Mixed methods including eight systematic reviews, three prioritisation exercises, two pilot randomised controlled trials (RCTs), three feasibility studies, two core outcome initiatives, four funding proposals for national RCTs and one completed national RCT.

Setting

Secondary care, primary care and the general population.

Participants

Patients (and their caregivers) with eczema, vitiligo, SCC and PG, plus health-care professionals with an interest in skin disease.

Interventions

Our three intervention studies included (1) barrier enhancement using emollients from birth to prevent eczema (pilot RCT); (2) handheld narrowband ultraviolet light B therapy for treating vitiligo (pilot RCT); and (3) oral ciclosporin (Neoral®, Novartis Pharmaceuticals) compared with oral prednisolone for managing PG (pragmatic national RCT).

Results

Systematic reviews included two overarching systematic reviews of RCTs of treatments for eczema and vitiligo, an umbrella review of systematic reviews of interventions for the prevention of eczema, two reviews of treatments for SCC (one included RCTs and the second included observational studies), and three reviews of outcome measures and outcome reporting. Three prioritisation partnership exercises identified 26 priority areas for future research in eczema, vitiligo and SCC. Two international consensus initiatives identified four core domains for future eczema trials and seven core domains for vitiligo trials. Two pilot RCTs and three feasibility studies critically informed development of four trial proposals for external funding, three of which are now funded and one is pending consideration by funders. Our pragmatic RCT tested the two commonly used systemic treatments for PG (prednisolone vs. ciclosporin) and found no difference in their clinical effectiveness or cost-effectiveness. Both drugs showed limited benefit. Only half of the participants’ ulcers had healed by 6 months. For those with healed ulcers, recurrence was common (30%). Different side effect profiles were noted for each drug, which can inform clinical decisions on an individual patient basis. Three researchers were trained to PhD level and a dermatology patient panel was established to ensure patient involvement in all aspects of the programme.

Conclusions

Findings from this programme of work have already informed clinical guidelines and patient information resources. Feasibility studies have ensured that large national pragmatic trials will now be conducted on important areas of treatment uncertainty that address the needs of patients and the NHS. There is scope for considerable improvement in terms of trial design, conduct and reporting for RCTs of skin disease, which can be improved through wider collaboration, registration of trial protocols and complete reporting and international consensus over core outcome sets. Three national trials have now been funded as a result of this work. Two international initiatives to establish how best to measure the core outcome domains for eczema and vitiligo are ongoing.

Trial registration

Current Controlled Trials Barrier Enhancement for Eczema Prevention (BEEP) (ISRCTN84854178 and NCT01142999), Study of Treatments fOr Pyoderma GAngrenosum Patients (STOP GAP) (ISRCTN35898459) and Hand Held NB-UVB for Early or Focal Vitiligo at Home (HI-Light Pilot Trial) (NCT01478945).

Funding

This project was funded by the National Institute for Health Research (NIHR) Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 4, No. 18. See the NIHR Journals Library website for further project information.

ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection

This report provides a review of stem cells/progenitor cells and their responses to ionising radiation in relation to issues relevant to stochastic effects of radiation that form a major part of the International Commission on Radiological Protection's system of radiological protection. Current information on stem cell characteristics, maintenance and renewal, evolution with age, location in stem cell 'niches', and radiosensitivity to acute and protracted exposures is presented in a series of substantial reviews as annexes concerning haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. This foundation of knowledge of stem cells is used in the main text of the report to provide a biological insight into issues such as the linear-no-threshold (LNT) model, cancer risk among tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. Knowledge of the biology and associated radiation biology of stem cells and progenitor cells is more developed in tissues that renew fairly rapidly, such as haematopoietic tissue, intestinal mucosa, and epidermis, although all the tissues considered here possess stem cell populations. Important features of stem cell maintenance, renewal, and response are the microenvironmental signals operating in the niche residence, for which a well-defined spatial location has been identified in some tissues. The identity of the target cell for carcinogenesis continues to point to the more primitive stem cell population that is mostly quiescent, and hence able to accumulate the protracted sequence of mutations necessary to result in malignancy. In addition, there is some potential for daughter progenitor cells to be target cells in particular cases, such as in haematopoietic tissue and in skin. Several biological processes could contribute to protecting stem cells from mutation accumulation: (a) accurate DNA repair; (b) rapidly induced death of injured stem cells; (c) retention of the DNA parental template strand during divisions in some tissue systems, so that mutations are passed to the daughter differentiating cells and not retained in the parental cell; and (d) stem cell competition, whereby undamaged stem cells outcompete damaged stem cells for residence in the niche. DNA repair mainly occurs within a few days of irradiation, while stem cell competition requires weeks or many months depending on the tissue type. The aforementioned processes may contribute to the differences in carcinogenic radiation risk values between tissues, and may help to explain why a rapidly replicating tissue such as small intestine is less prone to such risk. The processes also provide a mechanistic insight relevant to the LNT model, and the relative and absolute risk models. The radiobiological knowledge also provides a scientific insight into discussions of the dose and dose-rate effectiveness factor currently used in radiological protection guidelines. In addition, the biological information contributes potential reasons for the age-dependent sensitivity to radiation carcinogenesis, including the effects of in-utero exposure.

Human epidermal stem cells: Role in adverse skin reactions and carcinogenesis from radiation

In human skin, keratinopoiesis is based on a functional hierarchy among keratinocytes, with rare slow-cycling stem cells responsible for the long-term maintenance of the tissue through their self-renewal potential, and more differentiated daughter progenitor cells actively cycling to permit epidermal renewal and turn-over every month. Skin is a radio-responsive tissue, developing all types of radiation damage and pathologies, including early tissue reactions such as dysplasia and denudation in epidermis, and later fibrosis in the dermis and acanthosis in epidermis, with the TGF-beta 1 pathway as a known master switch. Also there is a risk of basal cell carcinoma, which arises from epidermal keratinocytes, notably after oncogenic events in PTCH1 or TP53 genes. This review will cover the mechanisms of adverse human skin reactions and carcinogenesis after various types of exposures to ionizing radiation, with comparison with animal data when necessary, and will discuss the possible role of stem cells and their progeny in the development of these disorders. The main endpoints presented are basal cell intrinsic radiosensitivity, genomic stability, individual factors of risk, dose specific responses, major molecular pathways involved and the cellular origin of skin reactions and cancer. Although major advances have been obtained in recent years, the precise implications of epidermal stem cells and their progeny in these processes are not yet fully characterized.

Basal cell carcinoma after treatment of childhood acute lymphoblastic leukemia and concise review of the literature

Basal cell carcinoma (BCC) is a rare secondary malignancy which may occur more often in children with acute lymphoblastic leukemia (ALL) who have previously received radiation therapy compared to to those who received no radiation.

Radiation-exposed populations: who, why, and how to study

Everyone is exposed to natural and manmade ionizing radiation that can originate from sources in the environment and in medical and occupational settings. There is notable variation, however, among individuals and across populations in the types of sources of radiation and in the frequency, level, and duration of exposure. Adverse health effects associated with radiation exposure have been known for decades, and ionizing radiation exposure has been linked with a broad range of different types of cancer and benign neoplasms as well as birth defects, reproductive effects, and diseases of the circulatory, hematologic, and neurologic systems. Our present understanding of radiation-related health risks derives primarily from multidisciplinary health risk (epidemiologic) studies that provide the key information on radiation-associated health outcomes, quantify radiation-related disease risks, and enhance understanding of mechanisms of radiation-related disease pathogenesis. Such information is central to quantifying risks in relation to benefits; addressing public concerns, including societal and clinical needs in relation to radiation exposure; and providing the database needed for establishing recommendations for radiation protection. Because of the importance of determining risks compared to benefits for all situations where exposure to ionizing radiation might result, it is useful for planning new health risks studies to categorize exposed populations according to the sources and types of radiation. This paper describes a wide range of populations exposed to radiation and the motivation and key methodological criteria that drive the rationale and priority of studying such populations. Also, discussed are alternative methods for evaluating radiation-related health risks in these populations, with a major focus on epidemiologic approaches. This paper concludes with a short summary of major highlights from radiation epidemiologic research and important unanswered questions.Introduction of Exposed Populations (Video 1:29, http://links.lww.com/HP/A22).

Mitochondrial D310 D-Loop instability and histological subtypes in radiation-induced cutaneous basal cell carcinomas

BACKGROUND

Basal cell carcinoma (BCC) is the most frequent skin cancer. An elevated prevalence of BCC has been associated with radiation, namely after the Tinea capitis epilation treatment, being these tumors described as more aggressive. Mitochondrial DNA (mtDNA) mutations have been reported in many human tumors, but their occurrence in BCC is poorly documented.

OBJECTIVE

The purpose of this work was to evaluate BCC histological subtypes in individuals subjected to X-ray epilation for Tinea capitis treatment when compared to non-irradiated patients. Moreover we also wanted to evaluate mitochondrial D-Loop instability in both groups of BCCs in order to compare the frequency of D-Loop mutations in post-irradiation BCC versus sporadic BCC.

METHODS

228 histological specimens corresponding to BCCs from 75 irradiated patients and 60 non-irradiated patients were re-evaluated for histological subtype. Subsequently, we sequenced the D-Loop 310 repeat in blood, oral mucosa, tumor lesions and, whenever available, non-tumoral adjacent tissue from these patients.

RESULTS

The infiltrative subtype of BCC, considered to be more aggressive, was significantly more frequent in irradiated patients. BCC D-Loop D310 mutation rate was significantly higher in irradiated BCCs than in the non-irradiated ones. Moreover, it was associated with a higher irradiation dose. The presence of mtDNA heteroplasmy in patients' blood was associated with a higher mutation rate in the BCCs suggesting that a more unstable genotype could predispose to mtDNA somatic mutation.

CONCLUSIONS

Our results suggest that radiation-induced BCCs may be considered to be more aggressive tumors. Further studies are needed to clarify the role of mtDNA D-Loop mutations in tumors from irradiated patients.

Associations between toenail arsenic concentration and dietary factors in a New Hampshire population

BACKGROUND

Dietary factors such as folate, vitamin B12, protein, and methionine are important for the excretion of arsenic via one-carbon metabolism in undernourished populations exposed to high levels of arsenic via drinking water. However, the effects of dietary factors on toenail arsenic concentrations in well-nourished populations exposed to relatively low levels of water arsenic are unknown.

METHODS

As part of a population-based case-control study of skin and bladder cancer from the USA, we evaluated relationships between consumption of dietary factors and arsenic concentrations in toenail clippings. Consumption of each dietary factor was determined from a validated food frequency questionnaire. We used general linear models to examine the associations between toenail arsenic and each dietary factor, taking into account potentially confounding effects.

RESULTS

As expected, we found an inverse association between ln-transformed toenail arsenic and consumption of vitamin B12 (excluding supplements) and animal protein. Unexpectedly, there were also inverse associations with numerous dietary lipids (e.g., total fat, total animal fat, total vegetable fat, total monounsaturated fat, total polyunsaturated fat, and total saturated fat). Finally, increased toenail arsenic concentrations were associated with increased consumption of long chain n-3 fatty acids.

CONCLUSION

In a relatively well-nourished population exposed to relatively low levels of arsenic via water, consumption of certain dietary lipids may decrease toenail arsenic concentration, while long chain n-3 fatty acids may increase toenail arsenic concentration, possibly due to their association with arsenolipids in fish tissue.

Cell type-dependent gene transcription profile in a three-dimensional human skin tissue model exposed to low doses of ionizing radiation: implications for medical exposures

The concern over possible health risks from exposures to low doses of ionizing radiation has been driven largely by the increase in medical exposures, the routine implementation of X-ray backscatter devices for airport security screening, and, most recently, the nuclear incident in Japan. Because of a paucity of direct epidemiological data at very low doses, cancer risk must be estimated from high dose exposure scenarios. However, there is increasing evidence that low and high dose exposures result in different signaling events and may have different response mechanisms than higher doses. We have examined the radiation-induced temporal response after exposure to 10 cGy of an in vitro three dimensional (3D) human skin tissue model using microarray-based transcriptional profiling. Cell type-specific analysis showed significant changes in gene expression with the levels of >1,400 genes altered in the dermis and >400 genes regulated in the epidermis. The two cell layers rarely exhibited overlapping responses at the mRNA level. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) measurements validated the microarray data in both regulation direction and value. Key pathways identified relate to cell cycle regulation, immune responses, hypoxia, reactive oxygen signaling, and DNA damage repair. The proliferation status as well as the expression of PCNA was examined in histological samples. We discuss in particular the role of proliferation, emphasizing how the disregulation of cellular signaling in normal tissue may impact progression toward radiation-induced secondary diseases.

Epidemiology of basal cell carcinoma

Basal cell carcinoma is the most common malignant neoplasm in humans and its incidence has increased over the last decades. Its high frequency significantly burdens the health system, making the disease a public health issue. Despite the low mortality rates and the rare occurrence of metastases, the tumor may be locally invasive and relapse after treatment, causing significant morbidity. Exposure to ultraviolet radiation is the main environmental risk factor associated with its cause. However, other elements of risk are described, such as light skin phototypes, advanced age, family history of skin carcinoma, light eyes and blond hair, freckles in childhood and immunosuppression. Behavioral aspects such as occupational sun exposure, rural labor and sunburns at a young age also play a role. Between 30% and 75% of the sporadic cases are associated with patched hedgehog gene mutation, but other genetic changes are also described. The tumor is commonly found in concomitance with skin lesions related to chronic sun exposure, such as actinic keratoses, solar lentigines and facial telangiectasia. The prevention of basal cell carcinoma is based on the knowledge of risk factors, early diagnosis and treatment, as well as on the adoption of specific measures, particularly in susceptible populations. The authors present a review of the epidemiology of basal cell carcinoma.

The risk of squamous cell and basal cell cancer associated with psoralen and ultraviolet A therapy: a 30-year prospective study

BACKGROUND

By 1977, psoralen and ultraviolet A (PUVA) was established as a highly effective therapy for psoriasis. Because of concerns about potential long-term adverse effects, particularly cancer, the PUVA Follow-Up Study was established to assess long-term risk and benefits of PUVA.

OBJECTIVE

We sought to determine the association of certain squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) risk with exposure to PUVA.

METHODS

For nearly 30 years, this prospective cohort study of 1380 patients with psoriasis first treated with PUVA in 1975 to 1976 documented exposures and incident events including biopsy-proven skin cancers.

RESULTS

From 1975 to 2005, 351 of 1380 (25%) cohort patients developed 2973 biopsy-proven SCC and 330 (24%) developed 1729 BCCs. After adjusting for age, gender, and significant confounders, the risk of developing one or more SCC in a year was strongly associated with total number of PUVA treatments (350-450 vs <50 treatments, incidence rate ratio [IRR] = 6.01, 95% confidence interval [CI] = 4.41-8.20). When all tumors are included this risk is significantly higher (IRR = 20.92, 95% CI = 14.08-31.08). Corresponding risks for BCC were much lower (person counts IRR = 3.09, 95% CI = 2.36-4.06; tumor counts IRR = 2.12, 95% CI = 1.47-3.05).

LIMITATIONS

This was an observational prospective study of a cohort with severe psoriasis. An unknown factor associated with higher dose exposure to PUVA in our cohort that was not included in our analysis could account for the observed associations.

CONCLUSION

Exposure to more than 350 PUVA treatments greatly increases the risk of SCC. Exposure to fewer than 150 PUVA treatments has, at most, modest effects on SCC risk. Even high-dose exposure to PUVA does not greatly increase BCC risk. The risks of SCC in long-term PUVA-treated patients should be considered in determining the risk of this therapy relative to other treatments for severe psoriasis.

A huge infiltrating squamous cell carcinoma of the neck 46 years after radiotherapy of a haemangioma

BACKGROUND

There is a higher risk for malignant tumours in patients who underwent any kind of radiotherapy.

MAIN OBSERVATIONS

An 87-year-old patient with an extended squamous cell carcinoma of the neck was referred to our hospital. The large ulcerated tumour showed a deep infiltration of the para-vertebral muscles and the spinal processes C6-C7. The tumour was known since about six years and appeared about 46 years after low-dose radiotherapy of a cervical haemangioma of the neck in 1961. The large dimension of the tumour leaded to a radical surgical removal and a sufficient fast reconstruction strategy. The extended defect was covered by a pedicled lower musculocutaneous trapezius flap. No postoperative complications like partial necrosis, infection or movement disorders of the shoulder or a shoulder drop syndrome were seen. Ten weeks after the operation the patient showed a good functional and aesthetic result with no limitation of arm mobility. Two and a half years after radical intended surgery the patient was still alive and showed no recurrence of the tumour.

CONCLUSIONS

In conclusion there is a need for a life-time lasting dermatological supervision in patients with a history of radiotherapy in the past, because the handling of patients with such an enlarged tumour is complicated.

The combined influence of oral contraceptives and human papillomavirus virus on cutaneous squamous cell carcinoma

The vast majority of cutaneous squamous cell carcinoma (CSCC) will occur in those with fair complexion, tendency to burn, and high ultraviolet radiation (UVR) exposure. Organ transplant recipients also are an important population at great risk for CSCC. An association has been reported between oral contraceptive (OC) use, human papillomavirus virus (HPV) and cervical cancer, and there could be a similar association for CSCC. The cutaneous HPV β-E6 protein, a close cousin of the transformative E6 protein underlying anogenital cancers, has been shown to inhibit apoptosis in response to UVR damage and stimulate morphologic transformation in rodent fibroblast cell lines. Furthermore, OC use has been shown to enhance HPV transcription and may contribute to CSCC risk through this pathway.

Interventions for non-metastatic squamous cell carcinoma of the skin

BACKGROUND

Squamous cell carcinoma (SCC) is the second most common skin cancer, and is becoming increasingly common around the world. Left untreated, it may spread to other parts of the body, and, although the risk is low, it may ultimately lead to death. Surgical excision is the first line of treatment for most skin SCCs, although other forms of treatment are also used depending upon the nature and site of the tumour and individual participant factors. A multi-professional approach is therefore required for the management of people with this condition.

OBJECTIVES

To assess the effects of treatments for primary non-metastatic squamous cell carcinoma of the skin.

SEARCH STRATEGY

In February 2010 we searched for relevant trials in The Cochrane Skin Group Specialised Register, The Cochrane Library (Issue 1, 2010), MEDLINE, EMBASE, PsycINFO, AMED, LILACS, and the ongoing trials registries.

SELECTION CRITERIA

We only included randomised controlled trials (RCTs) of interventions for primary SCC of the skin. Inclusion criteria were: adults with one or more histologically proven primary SCCs of the skin which had not metastasised. The primary outcome measures were time to recurrence one to five years after treatment, and quality of life. Secondary outcomes included early treatment failure within six months, number of adverse events by the end of treatment, aesthetic appearance as assessed by the participant and clinician, discomfort to the participant during and after treatment, and death.

DATA COLLECTION AND ANALYSIS

Two authors (LL, FB-H) independently carried out study selection and assessment of methodological quality and data extraction.

MAIN RESULTS

One trial involving 65 people was included. This compared the time to recurrence in participants with aggressive skin SCC who were randomised to receive either adjuvant 13-cis-retinoic acid and interferon alpha after surgery with or without radiation treatment, or no adjuvant therapy after their initial treatment. There was no significant difference in time to recurrence of tumour between the two groups (hazard ratio 1.08, 95% confidence intervals 0.43 to 2.72).Most studies identified from the searches were excluded as they were either uncontrolled case series, did not include participants with invasive primary SCC, or included only participants with recurrent or metastatic disease.

AUTHORS' CONCLUSIONS

Little evidence from RCTs comparing the efficacy of different interventions for primary cutaneous SCCs exists. There is a clear need for well-designed randomised studies in order to improve the evidence base for the management of this condition.

Potential risk factors for cutaneous squamous cell carcinoma include oral contraceptives: results of a nested case-control study

Recently, a population-based case-control study observed a 60% increased odds ratio (OR) for cutaneous squamous cell carcinoma (SCC) among women who had ever used oral contraceptives (OCs) compared with non users (95% confidence interval (CI) = 1.0-2.5). To further characterize the putative association between OC use and SCC risk, we conducted a nested case-control study using a large retrospective cohort of 111,521 Kaiser Permanente Northern California members. Multivariable conditional logistic regression was used to estimate ORs and CIs adjusting for known and hypothesized SCC risk factors. Pre-diagnostic OC use was associated with a statistically significant increased OR for SCC in univariate analysis (OR = 2.4, CI = 1.2-4.8), with borderline statistical significance in multivariable analysis (CI = 2.0, CI = 0.91-4.5). Given the high incidence of SCC in the general population and the prevalent use of OCs among women in the United States, there is a need for more large, carefully designed epidemiologic studies to determine whether the observed association between OC use and SCC can be replicated and to better understand the etiologic basis of an association if one exists.

An evolutionary perspective on parasitism as a cause of cancer

For the past half-century, the dominant paradigm of oncogenesis has been mutational changes that disregulate cellular control of proliferation. Parasitic causes of cancer were first incorporated into this paradigm by suggesting mechanisms through which parasitism might increase mutational damage, such as generation of mutagenic compounds during immunological activity. The growing recognition of the molecular mechanisms of pathogen-induced oncogenesis and the difficulty of generating oncogenic mutations without first having large populations of dysregulated cells, however, suggests that pathogens, particularly viruses, are major initiators of oncogenesis for many if not most cancers, and that the traditional mutation-driven process becomes the dominant process after this initiation. Molecular phylogenies of individual cancers should facilitate testing of this idea and the identification of causal pathogens.

Genetic background modulates gene expression profile induced by skin irradiation in ptch1 mice

PURPOSE

Ptch1 germ-line mutations in mice predispose to radiation-induced basal cell carcinoma of the skin, with tumor incidence modulated by the genetic background. Here, we examined the possible mechanisms underlying skin response to radiation in F1 progeny of Ptch1(neo67/+) mice crossed with either skin tumor-susceptible (Car-S) or -resistant (Car-R) mice and X-irradiated (3 Gy) at 2 days of age or left untreated.

METHODS AND MATERIALS

We conducted a gene expression profile analysis in mRNA samples extracted from the skin of irradiated or control mice, using Affymetrix whole mouse genome expression array. Confirmation of the results was done using real-time reverse-transcriptase polymerase chain reaction.

RESULTS

Analysis of the gene expression profile of normal skin of F1 mice at 4 weeks of age revealed a similar basal profile in the nonirradiated mice, but alterations in levels of 71 transcripts in irradiated Ptch1(neo67/+) mice of the Car-R cross and modulation of only eight genes in irradiated Ptch1(neo67/+) mice of the Car-S cross.

CONCLUSIONS

These results indicate that neonatal irradiation causes a persistent change in the gene expression profile of the skin. The tendency of mice genetically resistant to skin tumorigenesis to show a more complex pattern of transcriptional response to radiation than do genetically susceptible mice suggests a role for this response in genetic resistance to basal cell tumorigenesis.