Can oral nonsteroidal antiinflammatory drugs play a role in the prevention of basal cell carcinoma? A systematic review and metaanalysis

European consensus-based interdisciplinary guideline for diagnosis and treatment of basal cell carcinoma-update 2023

Basal cell carcinoma (BCC) is the most common malignant tumour in white populations. Multidisciplinary experts from European Association of Dermato-Oncology (EADO), European Dermatology Forum, European Society for Radiotherapy and Oncology (ESTRO), Union Européenne des Médecins Spécialistes, and the European Academy of Dermatology and Venereology developed updated recommendations on diagnosis and treatment of BCC. BCCs were categorised into 'easy-to-treat' (common) and 'difficult-to-treat' according to the new EADO clinical classification. Diagnosis is based on clinico-dermatoscopic features, although histopathological confirmation is mandatory in equivocal lesions. The first-line treatment of BCC is complete surgery. Micrographically controlled surgery shall be offered in high-risk and recurrent BCC, and BCC located on critical anatomical sites. Topical therapies and destructive approaches can be considered in patients with low-risk superficial BCC. Photodynamic therapy is an effective treatment for superficial and low-risk nodular BCCs. Management of 'difficult-to-treat' BCCs should be discussed by a multidisciplinary tumour board. Hedgehog inhibitors (HHIs), vismodegib or sonidegib, should be offered to patients with locally advanced and metastatic BCC. Immunotherapy with anti-PD1 antibodies (cemiplimab) is a second-line treatment in patients with a progression of disease, contraindication, or intolerance to HHI therapy. Radiotherapy represents a valid alternative in patients who are not candidates for or decline surgery, especially elderly patients. Electrochemotherapy may be offered when surgery or radiotherapy is contraindicated. In Gorlin patients, regular skin examinations are required to diagnose and treat BCCs at an early stage. Long-term follow-up is recommended in patients with high-risk BCC, multiple BCCs, and Gorlin syndrome.

[Current Management of Basal Cell Carcinoma]

For the management of basal cell carcinoma, the primary performance of a risk stratification, which is decisive for the further diagnostic and therapeutic steps, is becoming increasingly important.Various non-invasive methods are available to confirm the clinical diagnosis. Histological confirmation of the diagnosis is recommended in unclear cases. In poorly displaced lesions, preoperative cross-sectional imaging of the tumor area should be performed to exclude osseous infiltration.The gold standard in treatment remains surgery, which should be performed by means of micrographically controlled surgery if possible. In addition, there are other therapeutic methods such as radiotherapy or a number of topical therapy options (photodynamic therapy, cryotherapy or application of 5-fluorouracil or imiquimod), which can be used in certain cases. Also for advanced or metastatic basal cell carcinoma, effective drugs are available in the form of the hedgehog inhibitors, for which there is now several years of application experience with regard to efficacy and handling of adverse events. With the PD-1 inhibitor cemiplimab, a further therapeutic option for non-operable or metastatic tumors has been available since June 2021.The most important preventive measure is consistent textile or chemical UV protection in already affected individuals. In addition, nicotinamide and celecoxib can be used orally for prevention. For follow-up, the current S2k guideline recommends regular self-monitoring and standardized medical check-ups.

Basal Cell Carcinoma Perineural Invasion and Suggestive Signs of Perineural Invasion-Findings and Perspectives

Basal cell carcinoma (BCC) is a malignant tumor with a rising incidence and is the beneficiary of several innovative evaluation techniques. Histopathology remains the gold standard for assessment, having the possibility of addressing multiple high-risk factors such as perineural invasion (PNI). The current study included a number of 244 BCC patients and targeted the identification of positive PNI and its suggestive signs, and whether they correlated or not with other high-risk tumor signs. PNI was found in 20.1% of patients, with 30.7% of patients having perineural chronic inflammation (PCI), which is a suggestive sign of PNI. PNI was also found in larger tumors, with deeper Clark levels, in high-risk BCCs and high-grade tumors. PNI and PCI are both important for pathology reporting, aiding in treatment choice and further patient management, with possibly positive outcomes concerning morbidity and mortality.

The Association Between Aspirin and Basal Cell Carcinoma: A Clinical and Financial Analysis

Background

Nonmelanoma skin cancer (NMSC) is the most common malignancy. Basal cell carcinoma (BCC) comprises about 80% of all NMSCs and its incidence continues to rise. Although BCC rarely leads to metastases or increased mortality, its effects on healthcare costs and quality of life are substantial. Aspirin may prevent the development of basal cell carcinoma (BCC) by the inhibition of cyclooxygenase (COX) enzymes, which are associated with carcinogenesis and inflammation. This study therefore examined the effect of aspirin on the risk of BCC, its clinical outcomes, and its treatment costs.

Methods

A retrospective study (2010 - 2018) was conducted using the Humana Health Insurance Database. International Classification of Disease ninth and 10th codes and National Drug Codes were used to identify BCC diagnoses and aspirin prescriptions. Patients were matched for age, sex, Charlson Comorbidity Score (CCI), and region of residence. Chi-squared, logistic regression, and odds ratio (OR) analyses were utilized to test for significance and to estimate relative risk.

Results

Aspirin use was associated with a decreased incidence of BCC in unmatched (OR = 0.658, 95% confidence interval (CI) 0.526 - 0.820) and matched (OR = 0.54, 95% CI 0.47 - 0.61) analyses. Aspirin was also associated with a decreased BCC risk when stratified by hypertension (P = 3.888 × 10^-5), chronic obstructive pulmonary disease (COPD) (P = 0.014), diabetes (P = 0.049) and tobacco use (P = 0.017). Aspirin use was not associated with risk of BCC when stratified by obesity (P = 0.408). The average paid per patient for BCC treatment was significantly higher for patients in the aspirin use group than in the aspirin nonuse group (P = 0.0087).

Conclusions

While the high incidence and cost of treatment of BCC are demanding both clinically and financially, the low cost of aspirin and its widespread use may have vital implications for its preventative role in this disease. This study concluded that aspirin use was associated with a significantly decreased risk of BCC.

[Current Management of Basal Cell Carcinoma]

AIM OF STUDY

We present the current standard in diagnosis and treatment of basal cell carcinoma. Useful procedures for clinical management should be derived from this.

METHODS

A systematic literature search was carried out in the PubMed online database. The collected information was analyzed and evaluated. An overall concept was created from the gained knowledge.

RESULTS

Basal cell carcinoma is the most common tumor in humans and its incidence is expected to increase in the future. When managing the disease, a one-dimensional orientation towards the clinical or histological subtype is not sufficient because of the heterogeneity of the tumor. The primary implementation of risk stratification, which is decisive for the further diagnostic and therapeutic steps, is becoming increasingly important. The gold standard in treatment continues to be the surgical procedure, which should be carried out using micrographically controlled surgery if possible. In addition, there are other therapeutic methods such as radiotherapy or a number of topical therapy options (photodynamic therapy, cryotherapy, application of 5-fluorouracil or imiquimod), which can be used in certain cases. Hedgehog inhibitors are also effective drugs for advanced or metastatic basal cell carcinoma. Practitioners have gained several years of experience with regard to effectiveness and handling of adverse events. With the PD-1 inhibitor cemiplimab, another therapeutic option for inoperable or metastatic tumors has been available since June 2021.

CONCLUSION

Basal cell carcinoma will continue to gain in relevance in daily dermatological practice in the coming years. A structured approach to the assessment of the existing risk category of the tumor and the subsequent determination of the optimal therapy regimen are of central importance. Advanced or metastatic tumors no longer represent a hopeless situation for the patient. With long-termhedgehog therapy, an adapted dosage scheme can avoid discontinuation of therapy due to side effects. The therapeutic potential of the PD-1 inhibitor cemiplimab can also be used with the side effect profile known from other types of skin cancer.

Effect of Aspirin on Melanoma Incidence in Older Persons: Extended Follow-up of a Large Randomized Double-blind Placebo-controlled Trial

The effects of aspirin on melanoma are unclear, with studies reporting conflicting results. Data from two periods of the ASPirin in Reducing Events in the Elderly (ASPREE) study; the randomized placebo-controlled trial period examining daily 100 mg aspirin in older adults with a median follow-up of 4.7 years, and the second period, an additional 2 years of observational follow-up, were utilized in this secondary analysis to examine whether aspirin exposure is associated with a reduced cutaneous melanoma incidence. All melanoma cases were adjudicated and Cox proportional hazards models were used to compare incidence between randomized treatment groups. ASPREE recruited 19,114 participants with a median age of 74 years. During the trial period, 170 individuals (76 aspirin, 94 placebo) developed an invasive melanoma, and no significant effect of aspirin was observed on incident melanoma [HR = 0.81; 95% confidence interval (CI), 0.60-1.10]. Including the additional 2 years of observational follow-up (median follow-up of 6.3 years), 268 individuals (119 aspirin, 149 placebo) developed an invasive melanoma, and similar results were observed (HR = 0.81; 95% CI, 0.63-1.03). A reduced number of events was observed with aspirin among females in a subgroup analysis (HR = 0.65; 95% CI, 0.44-0.92); however, the interaction effect with males (HR = 0.92; 95% CI, 0.68-1.25) was nonsignificant (P = 0.17). Our findings from this randomized trial do not provide strong support that aspirin is associated with a reduced risk of invasive melanoma in older individuals. Additional studies are required to further explore this relationship.

PREVENTION RELEVANCE

Melanoma prevention is an important strategy to improve outcomes and while preventive efforts have largely focused on sun protection, the role of potential chemopreventive agents such as aspirin warrants investigation.

Aktuelles Management des Basalzellkarzinoms

Ziel der Studie Der aktuelle Standard von Diagnostik und Therapie des Basalzellkarzinoms soll dargestellt werden. Hieraus sollen sinnvolle Vorgehensweisen für das klinische Management abgeleitet werden.

Methodik Es erfolgte eine systematische Literaturrecherche in der Online-Datenbank PubMed. Die gesammelten Informationen wurden analysiert und bewertet. Aus den gewonnenen Erkenntnissen wurde ein Gesamtkonzept erstellt.

Ergebnisse Das Basalzellkarzinom ist der häufigste Tumor des Menschen und die Inzidenz wird voraussichtlich künftig weiter zunehmen. Beim Management der Erkrankung wird eine eindimensionale Orientierung am klinischen bzw. histologischen Basalzellkarzinom-Subtyp der Heterogenität des Tumors nicht gerecht. Zunehmende Bedeutung gewinnt die primäre Durchführung einer Risikostratifizierung, die für die weiteren diagnostischen und therapeutischen Schritte maßgeblich ist. Goldstandard in der Behandlung bleibt weiterhin das operative Vorgehen, welches möglichst mittels mikrografisch kontrollierter Chirurgie erfolgen sollte. Daneben existieren weitere Therapieverfahren wie die Radiotherapie oder eine Reihe an topischen Therapieoptionen (photodynamische Therapie, Kryotherapie oder Applikation von 5-Fluoruracil bzw. Imiquimod), die in bestimmten Fällen zur Anwendung kommen können. Auch für fortgeschrittene oder metastasierte Basalzellkarzinome stehen mit den Hedgehog-Inhibitoren wirksame Medikamente zur Verfügung, für die inzwischen eine mehrjährige Anwendungserfahrung hinsichtlich Wirksamkeit und Umgang mit unerwünschten Ereignissen vorliegt. Mit den PD-1-Inhibitoren steht eine weitere systemische Therapieoption in Aussicht, deren Nutzen aktuell noch in klinischen Studien überprüft wird.

Schlussfolgerung Das Basalzellkarzinom wird in den kommenden Jahren weiter an Relevanz in der täglichen dermatologischen Praxis gewinnen. Eine strukturierte Herangehensweise zur Einschätzung der vorliegenden Risikokategorie des Tumors und die anschließende Festlegung des optimalen Therapieregimes sind von zentraler Bedeutung. Fortgeschrittene oder metastasierte Tumoren stellen keine aussichtslose Situation für den Patienten mehr dar. Durch adaptierte Dosierschemata kann ein nebenwirkungsbedingter Therapieabbruch unter langfristiger Hedgehog-Therapie vermieden werden. Das therapeutische Potenzial von PD-1-Inhibitoren könnte bald auch beim Basalzellkarzinom genutzt werden.

Assessing the compliance of systematic review articles published in leading dermatology journals with the PRISMA statement guidelines: A systematic review

Background

Reporting quality of systematic reviews and meta-analyses is of critical importance in dermatology because of their key role in informing health care decisions.

Objective

To assess the compliance of systematic reviews and meta-analyses in leading dermatology journals with the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement guidelines.

Methods

This review was carried out in accordance with PRISMA guidelines. Included studies were reviews published across 6 years in the top 4 highest-impact-factor dermatology journals of 2017. Records and full texts were screened independently. Data analysis was conducted with univariate multivariable linear regression. The primary outcome was to assess the compliance of systematic reviews and meta-analyses in leading dermatology journals with the PRISMA statement.

Results

A total of 166 studies were included and mean PRISMA compliance across all articles was 73%. Compliance significantly improved over time (β = .016; P = <.001). The worst reported checklist item was item 5 (reporting on protocol existence), with a compliance of 15% of articles.

Conclusion

PRISMA compliance within leading dermatology journals could be improved; however, it is steadily improving.

Basal Cell Carcinoma: From Pathophysiology to Novel Therapeutic Approaches

Basal cell carcinoma (BCC) is the most common human cancer worldwide, and is a subtype of nonmelanoma skin cancer, characterized by a constantly increasing incidence due to an aging population and widespread sun exposure. Although the mortality from BCC is negligible, this tumor can be associated with significant morbidity and cost. This review presents a literature overview of BCC from pathophysiology to novel therapeutic approaches. Several histopathological BCC subtypes with different prognostic values have been described. Dermoscopy and, more recently, reflectance confocal microscopy have largely improved BCC diagnosis. Although surgery is the first-line treatment for localized BCC, other nonsurgical local treatment options are available. BCC pathogenesis depends on the interaction between environmental and genetic characteristics of the patient. Specifically, an aberrant activation of Hedgehog signaling pathway is implicated in its pathogenesis. Notably, Hedgehog signaling inhibitors, such as vismodegib and sonidegib, are successfully used as targeted treatment for advanced or metastatic BCC. Furthermore, the implementation of prevention measures has demonstrated to be useful in the patient management.

S2k Guidelines for Cutaneous Basal Cell Carcinoma - Part 2: Treatment, Prevention and Follow-up

Basal cell carcinoma (BCC) is the most common malignant tumor among fair-skinned individuals, and its incidence had been steadily rising in the past decades. In order to maintain the highest quality of patient care possible, the German S2k guidelines were updated following a systematic literature search and with the participation of all professional societies and associations involved in the management of the disease. Part 2 addresses issues such as proper risk stratification, the various therapeutic approaches, and prevention as well as follow-up of patients with basal cell carcinoma.

Aspirin and Its Potential Preventive Role in Cancer: An Umbrella Review

Background: Aspirin is one of the most commonly prescribed drugs worldwide and has been reported to possess anti-cancer properties in addition to antipyretic and analgesic effects. This umbrella review summarizes systematic reviews and meta-analyses that investigate the association between aspirin and cancer risk, aiming to help clinical and public health decision-makers interpret the results of these studies when re-positioning aspirin. Methods: An umbrella review of systematic reviews and meta-analyses. Results: The associations that reached statistical significance (17 in total) indicated potential preventive effects of aspirin on certain cancers or precancerous lesions. We found that no association was supported by strong evidence. Only one association (aspirin and overall cancer risk) was supported by highly suggestive evidence. The evidence supporting the association between aspirin and the risk of breast cancer, non-cardia gastric cancer, or prostate cancer was considered to be highly suggestive. The remaining 23 associations were supported by weak (13) or not suggestive evidence (10). Conclusions: The association between aspirin and a reduced risk of esophageal squamous cell carcinoma is supported by strong evidence, researchers and policy makers should pay more attention to the potential merit of repositioning aspirin to prevent esophageal squamous cell carcinoma.

Hormone replacement therapy and the risk of melanoma in post-menopausal women

STUDY QUESTION

Is hormone replacement therapy (HRT) associated with an increased risk of melanoma skin cancer or prognostic outcomes amongst post-menopausal women?

SUMMARY ANSWER

Whilst we found evidence of an association with melanoma risk, the lack of dose-response and associations observed with recent use, localised disease and intravaginal oestrogens suggests this is a non-causal association.

WHAT IS KNOWN ALREADY

Evidence on HRT and melanoma risk remains inconclusive, with studies providing conflicting results. Furthermore, evidence on melanoma survival is sparse, with only one previous study reporting protective associations with HRT use, likely attributable to immortal time bias.

STUDY DESIGN, SIZE, DURATION

We conducted a nation-wide population-based case-control study and a retrospective cohort study utilising the Danish healthcare registries. Case-control analyses included 8279 women aged 45-85 with a first-ever diagnosis of malignant melanoma between 2000 and 2015, matched by age and calendar time to 165 580 population controls. A cohort of 6575 patients with a diagnosis of primary malignant melanoma between 2000 and 2013 and followed through 2015 was examined to determine if HRT use had an impact on melanoma survival outcomes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Based on prescriptions dispensed since 1995, ever-use of HRT was defined as having filled at least one prescription for HRT prior to the index date. In total, 2629 cases (31.8%) and 47 026 controls (28.4%) used HRT. Conditional logistic regression was used to calculate odds ratios (ORs) for melanoma risk according to HRT use, compared with non-use, adjusting for potential confounders. For cohort analyses, Cox proportional hazards models was used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) for second melanoma incidence and all-cause mortality associated with HRT.

MAIN RESULTS AND THE ROLE OF CHANCE

High use of HRT was associated with an OR of 1.21 (95% CI 1.13-1.29) for melanoma risk, with no evidence of a dose-response pattern. Results were most pronounced amongst recent high users (OR, 1.28; 95% CI 1.17-1.41), for localised disease (OR, 1.25; 95% CI 1.15-1.36) and for intravaginal oestrogen therapy (OR, 1.38; 95% CI 1.13-1.68). Compared with non-use, there was no evidence of an association for secondary melanoma for post-diagnostic new-use (fully adjusted HR, 1.56; 95% CI 0.64-3.80) or continuous HRT use (fully adjusted HR, 1.26; 95% CI 0.89-1.78). Similar associations were observed for all-cause mortality.

LIMITATIONS, REASONS FOR CAUTION

Despite the large sample size and the use of robust population-based registries with almost complete coverage, we lacked information on some important confounders including sun exposure.

WIDER IMPLICATIONS OF THE FINDINGS

Whilst we cannot rule out an association between HRT use and melanoma risk, the associations observed are also compatible with increased healthcare utilisation and thus increased melanoma detection amongst HRT users. No association between HRT use and melanoma survival outcomes was observed. This should provide some reassurance to patients and clinicians, particularly concerning the use of HRT in patients with a history of melanoma.

STUDY FUNDING/COMPETING INTEREST(S)

B.M.H. is funded by a Cancer Research UK Population Research Postdoctoral Fellowship. The funding source had no influence on the design or conduct of this study. A.P. reports participation in research projects funded by Alcon, Almirall, Astellas, Astra-Zeneca, Boehringer-Ingelheim, Servier, Novo Nordisk and LEO Pharma, all with funds paid to the institution where he was employed (no personal fees) and with no relation to the work reported in this article. The other authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

N/A.

The association between nonsteroidal anti-inflammatory drugs and skin cancer: Different responses in American and European populations

OBJECTIVE

To conduct a comprehensive systematic meta-analysis investigating the association of nonsteroidal anti-inflammatory drugs (NSAIDs) and their subtypes with skin cancer (SC) and its subclasses (basal cell carcinoma BCC; squamous cell carcinoma SCC; melanoma; nonmelanoma skin cancer NMSC) in general, American and European populations.

METHODS

PubMed, Embase, the Cochrane Library, the China National Knowledge Infrastructure and ClinicalTrials.gov were searched up to 24 February 2019. Pooled effect sizes and 95% confidence intervals were used to estimate associations.

RESULTS

Results based on 26 original studies including 223,619 cases and 1,398,507 controls showed both NSAIDs and nonselective Cyclooxygenase (COX) inhibitors to be statistically significantly associated with a reduced risk of SC, BCC, SCC and NMSC but not with melanoma. Conversely, no association was observed between selective Cyclooxygenase 2 (COX-2) inhibitors and SC or its subclasses. Further subgroup analysis showed that the results analyzed for American populations were almost the same as those for the general population. For European populations, neither NSAIDs nor its subtypes correlated significantly with susceptibility to SC or its subclasses.

CONCLUSIONS

The use of NSAIDs might reduce the risk of SC, but many factors including study population, drug subtype, and disease subclass affect the significance of the association.

Inflammation: A key process in skin tumorigenesis

The extremely delicate shift from an inflammatory process to tumorigenesis is a field of major scientific interest. While the inflammation induced by environmental agents has well known underlying mechanisms, less is known concerning the oncogenic changes that follow an inflammatory chronic status in the tissue microenvironment that can lead to pro-tumorigenic processes. Regardless of the origin of the environmental factors, the maintenance of an inflammatory microenvironment is a clear condition that favors tumorigenesis. Inflammation sustains the proliferation and survival of malignant transformed cells, can promote angiogenesis and metastatic processes, can negatively regulate the antitumoral adaptive and innate immune responses and may alter the efficacy of therapeutic agents. There is an abundance of studies focusing on molecular pathways that trigger inflammation-mediated tumorigenesis, and these data have revealed a series of biomarkers that can improve the diagnosis and prognosis in oncology. In skin there is a clear connection between tissue destruction, inflammation and tumor onset. Inflammation is a self-limiting process in normal physiological conditions, while tumor is a constitutive process activating new pro-tumor mechanisms. Among skin cancers, the most commonly diagnosed skin cancers, squamous cell carcinoma and basal cell carcinoma (BCC) have important inflammatory components. The most aggressive skin cancer, melanoma, is extensively research in regards to the new context of novel developed immune-therapies. In skin cancers, inflammatory markers can find their place in the biomarker set for improvement of diagnosis and prognosis.

Risk of basal cell carcinoma in a randomized clinical trial of aspirin and folic acid for the prevention of colorectal adenomas

BACKGROUND

Aspirin may reduce the risk of several types of cancer.

OBJECTIVES

To evaluate if folic acid is associated with risk of basal cell carcinoma (BCC).

METHODS

BCC incidence was evaluated in a randomized, double-blind, placebo-controlled clinical trial of aspirin (81 mg daily or 325 mg daily for ~3 years) and/or folic acid (1 mg daily for ~6 years) for the prevention of colorectal adenomas among 1121 participants with a previous adenoma. BCC was confirmed by blinded review of pathology reports.

RESULTS

One hundred and four of 958 non-Hispanic white participants were diagnosed with BCC over a median follow-up of 13·5 years. Cumulative incidence of BCC was 12% [95% confidence interval (CI) 7-17] for placebo, 16% (95% CI 11-21) for 81 mg aspirin daily and 15% (95% CI 10-20) for 325 mg aspirin daily [hazard ratio (HR) for any aspirin 1·45 (95% CI 0·93-2·26); HR for 81 mg daily 1·57 (95% CI 0·96-2·56); HR for 325 mg daily 1·33 (95% CI 0·80-2·20)]. BCC risk was higher with aspirin use in those without previous skin cancer but lower with aspirin use in those with previous skin cancer (P_interaction = 0·02 for 81 mg aspirin daily; P_interaction = 0·03 for 325 mg aspirin daily). Folic acid supplementation was unrelated to BCC incidence (HR 0·85; 95% CI 0·57-1·27).

CONCLUSIONS

Neither aspirin nor folic acid treatment had a statistically significant effect on risk of BCC. Subgroup analysis suggested that chemopreventive effects of nonsteroidal anti-inflammatory drugs may be specific to those at high risk for BCC.

Cutaneous squamous cell carcinoma: an epidemiological review

Cutaneous squamous cell carcinoma (SCC) is a common cancer in white populations and its disease burden is often substantially underestimated. SCC occurs more often in men than women and increases dramatically with age; those affected often develop multiple primaries over time, which increases the burden. The main external cause is solar ultraviolet radiation (UVR), with immunosuppression being the other established risk factor, shown by the high SCC rates in organ transplant recipients. Sunbed use and certain genetic disorders and medical conditions are also associated with SCC, while associations with human papillomavirus infection and high bodyweight are not established. The presence of actinic keratoses (AKs) on sun-damaged skin is one of the strongest predictors of SCC in unaffected people and a very small proportion of AKs are SCC precursors, although the true rate of malignant transformation of AKs is unknown. The mainstay of SCC prevention is protection of the skin from undue sun exposure by use of clothing cover and sunscreen during summer or in sunny places. Educational, behavioural and multicomponent interventions directed at individuals ranging from parents of newborns, to school children and adolescents, to outdoor workers, have repeatedly been shown to be effective in improving sun-protective behaviours. Health policies can facilitate SCC prevention by setting standards for relevant behaviours to reduce UVR exposure, for example, by legislated restriction of the tanning industry. Skin cancer prevention initiatives are generally highly cost-effective and public investment should be encouraged to control the growing public health problems caused by SCC.

Non-genetic risk factors for cutaneous melanoma and keratinocyte skin cancers: An umbrella review of meta-analyses

BACKGROUND

Skin cancers have a complex disease mechanism, involving both genetic and non-genetic risk factors. Numerous meta-analyses have been published claiming statistically significant associations between non-genetic risk factors and skin cancers without applying a thorough methodological assessment.

OBJECTIVE

The present study maps the literature on the non-genetic risk factors of skin cancers, assesses the presence of statistical biases and identifies the associations with robust evidence.

METHODS

We searched PubMed up to January 20, 2016 to identify systematic reviews and meta-analyses of observational studies that examined associations between non-genetic factors and skin cancers. For each meta-analysis, we estimated the summary effect size by random-effects and fixed-effects models, the 95% confidence interval and the 95% prediction interval. We also assessed the between-study heterogeneity (I2 metric), evidence for small-study effects and excess significance bias.

RESULTS

Forty-four eligible papers were identified and included a total of 85 associations. Twenty-one associations were significant at P<10-6. Fifty-two associations had large or very large heterogeneity. Evidence for small-study effects and excess significance bias was found in fifteen and thirteen associations, respectively. Overall, thirteen associations (actinic keratosis, serum vitamin D, sunburns, and hair color for basal cell carcinoma and density of freckles, eye color, hair color, history of melanoma, skin type, sunburns, premalignant skin lesions, common and atypical nevi for melanoma) presented high level of credibility.

CONCLUSION

The majority of meta-analyses on non-genetic risk factors for skin cancers suffered from large between-study heterogeneity and small-study effects or excess significance bias. The associations with convincing and highly suggestive evidence were mainly focused on skin photosensitivity and phenotypic characteristics.