Nonsteroidal anti-inflammatory drugs and the risk of nonmelanoma skin cancer

Spectrum of malignant and premalignant skin lesions in 505 adult subjects at risk of skin cancers

Patients at risk of skin cancers can develop varying types of cutaneous malignancies. However, some subjects may develop only one type of lesion. In this cross-sectional study, the spectrum of premalignant (PM) and malignant skin lesions and their risk factors were studied. Therefore, 505 adult subjects (aged 21-79 years, 256 males and 249 females, 96 with immunosuppression) at risk of any type of skin cancer were examined for cutaneous malignancies, nevi, actinic keratoses, photodamage, and possible risk factors. First, 12 different groups were identified with a varying set of PM and/or malignant skin lesions. Next, 5 larger groups were formed from them: basal cell carcinoma (BCC) only, malignant melanoma (MM) only, squamous cell carcinoma (SCC) and/or PM, BCC + SCC and/or PM, and MM + keratinocyte carcinoma (KC) and/or PM. The groups with BCC or MM only were younger and showed less photodamage than the mixed groups, while SCC/PM showed similarity with them. In logistic regression analyses, the platelet-to-lymphocyte ratio was associated with an increased risk of concomitant KC (OR 1.028, p = 0.023) or SCC/PM (OR 1.009, p = 0.047) in subjects with MM or BCC, respectively. Actinic keratoses produced ORs 0.246-0.252 (p = 0.008-0.020) for BCC in subjects with SCC/PM. Interestingly, atypical mole syndrome decreased the risk of SCC/PM in subjects with BCC (OR 0.092, p = 0.001). Advanced age was a significant risk factor for an additional type of lesion in all 3 comparisons (ORs 1.088-1.388, p = 0.001). In conclusion, even though there are numerous patients with only one lesion type, advancing age may determine the final lesion multiplicity.

European consensus-based interdisciplinary guideline for invasive cutaneous squamous cell carcinoma. Part 1: Diagnostics and prevention-Update 2023

Invasive cutaneous squamous cell carcinoma (cSCC) is one of the most common cancers in white populations, accounting for 20% of all cutaneous malignancies. Overall, cSCC mostly has very good prognosis after treatment, with 5-year cure rates greater than 90%. Despite the overall favourable prognosis and the proportionally rare deaths, cSCC is associated with a high total number of deaths due to its high incidence. A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology (EADO), the European Dermatology Forum (EDF), the European Society for Radiotherapy and Oncology (ESTRO), the European Union of Medical Specialists (UEMS), the European Academy of Dermatology and Venereology (EADV) and the European Organization of Research and Treatment of Cancer (EORTC), was formed to update recommendations on cSCC, based on current literature and expert consensus. Part 1 of the guidelines addresses the updates on classification, epidemiology, diagnosis, risk stratification, staging and prevention in immunocompetent as well as immunosuppressed patients.

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.

COX-2 inhibitors show no preventive effect in the development of skin cancer

BACKGROUND

Some clinical trials found that cyclooxygenase-2 (COX-2) inhibitor use lowered the risk of skin cancer in high-risk groups.

PATIENTS AND METHODS

To determine whether COX-2 inhibitor use is associated with lower risk of basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (cSCC), and melanoma, we analyzed COX-2 inhibitor use and risk of skin cancer based on three prospective cohort studies, the Nurses' Health Study (NHS), NHS II, and the Health Professionals Follow-up Study, including 153,882 participants. Multivariable hazard ratios (HRs) and 95 % confidence intervals (CIs) for the association of COX-2 inhibitor use with risk of BCC, cSCC, and melanoma were estimated using Cox proportional hazards models. We pooled the results using a fixed effects model.

RESULTS

16,142 BCC, 1,973 cSCC, and 631 melanoma cases were documented. Ever vs. never use of COX-2 inhibitor was associated with a modestly increased risk of BCC (multivariable HR 1.09, 95 % CI 1.05-1.14). The hazard ratio was similar for cSCC (multivariable HR 1.12, 95 % CI 1.00-1.27) and melanoma (multivariable HR 1.10, 95 % CI 0.89-1.38), but was not statistically significant.

CONCLUSIONS

Ever use of COX-2 inhibitor was not associated with a decreased skin cancer risk but was instead associated with a modest, increased risk of BCC.

Prevention of UV-induced skin cancer in mice by gamma oryzanol-loaded nanoethosomes

AIMS

Skin cancer is the most widespread cancer worldwide, mainly caused by exposure to ultraviolet radiation (UV) in sunlight. Utilizing topical preventive agents in routinely daily used cosmetics may prevent UV-related skin damages and skin cancers. γ-Oryzanol (GO) is a natural component derived from rice bran oil, with potential antioxidant and skin anti-aging properties.

MAIN METHODS

We biologically thorough studied the antioxidant and anticancer effects of GO in vitro to found the effective signaling pathways, then evaluated the sun protection factor of prepared formulation, and finally investigated the long-term preventive effects of GO-loaded nanoethosomes (GO-NEs) against UVB-induced skin cancer in mice.

KEY FINDINGS

GO-NEs could effectively prevent UVB-induced skin cancer.

SIGNIFICANCE

Our results suggest that GO-NEs could be utilized as an innovative ingredient in cosmetics.

The role of drugs and selected dietary factors in cutaneous squamous cell carcinogenesis

Cutaneous squamous cell carcinoma represents the second most common non-melanoma skin cancer and its incidence increases worldwide. This review provides an overview of selected exogenous risk factors for cutaneous squamous cell carcinoma, which include drugs (azathioprine, calcineurin inhibitors, hydrochlorothiazide, angiotensin-converting-enzyme inhibitors) and few dietary factors (fat meet, whole milk products, arsenic) to better understand squamous skin cancer etiopathogenesis. Ingredients such as leafy vegetables, nuts, fish, caffeine, niacin are preventive factors for cutaneous squamous cell cancer. The heart transplant recipients have an increased risk of squamous cell carcinoma development than kidney or liver transplant ones and switching photosensitizing azathioprine to mycophenolate mofetil can reduce the incidence of cutaneous squamous cell carcinoma. The great attention should be paid to early change of cardiac photosensitizing antihypertensive drugs to non-photosensitizing ones among patients with a history of prior skin cancers and among organ transplant recipients. Based on current knowledge that ultra-violet radiation is the main risk factor for squamous cell carcinoma development, promotion of the skin self-examination, photoprotection, tanning bed avoidance and early skin cancer diagnosis is important for this tumour prevention.

Cutaneous Squamous Cell Carcinoma: From Pathophysiology to Novel Therapeutic Approaches

Cutaneous squamous cell carcinoma (cSCC), a non-melanoma skin cancer, is a keratinocyte carcinoma representing one of the most common cancers with an increasing incidence. cSCC could be in situ (e.g., Bowen’s disease) or an invasive form. A significant cSCC risk factor is advanced age, together with cumulative sun exposure, fair skin, prolonged immunosuppression, and previous skin cancer diagnoses. Although most cSCCs can be treated by surgery, a fraction of them recur and metastasize, leading to death. cSCC could arise de novo or be the result of a progression of the actinic keratosis, an in situ carcinoma. The multistage process of cSCC development and progression is characterized by mutations in the genes involved in epidermal homeostasis and by several alterations, such as epigenetic modifications, viral infections, or microenvironmental changes. Thus, cSCC development is a gradual process with several histological- and pathological-defined stages. Dermoscopy and reflectance confocal microscopy enhanced the diagnostic accuracy of cSCC. Surgical excision is the first-line treatment for invasive cSCC. Moreover, radiotherapy may be considered as a primary treatment in patients not candidates for surgery. Extensive studies of cSCC pathogenic mechanisms identified several pharmaceutical targets and allowed the development of new systemic therapies, including immunotherapy with immune checkpoint inhibitors, such as Cemiplimab, and epidermal growth factor receptor inhibitors for metastatic and locally advanced cSCC. Furthermore, the implementation of prevention measures has been useful in patient management.

Association between Use of Hydrochlorothiazide and Nonmelanoma Skin Cancer: Common Data Model Cohort Study in Asian Population

Although hydrochlorothiazide (HCTZ) has been suggested to increase skin cancer risk in white Westerners, there is scant evidence for the same in Asians. We analyzed the association between the use of hydrochlorothiazide and non-melanoma in the Asian population using the common data model.

METHODS

A retrospective multicenter observational study was conducted using a distributed research network to analyze the effect of HCTZ on skin cancer from 2004 to 2018. We performed Cox regression to evaluate the effects by comparing the use of HCTZ with other antihypertensive drugs. All analyses were re-evaluated using matched data using the propensity score matching (PSM). Then, the overall effects were evaluated by combining results with the meta-analysis.

RESULTS

Positive associations were observed in the use of HCTZ with high cumulative dose for non-melanoma skin cancer (NMSC) in univariate analysis prior to the use of PSM. Some negative associations were observed in the use of low and medium cumulative doses.

CONCLUSION

Although many findings in our study were inconclusive, there was a non-significant association of a dose-response pattern with estimates increasing in cumulative dose of HCTZ. In particular, a trend with a non-significant positive association was observed with the high cumulative dose of HCTZ.

Expression of Cyclooxygenase-2 in Human Epithelial Skin Lesions: A Systematic Review of Immunohistochemical Studies

Permanent, elevated expression of cyclooxygenase-2 (COX-2) in keratinocytes of epidermis can stimulate its hyperplasia and constitute a factor promoting cancer development, as demonstrated in animal models. Intratumoral level and localization of COX-2 in epithelial lesions of human skin was examined immunohistochemically in 26 studies. In squamous cell carcinomas (SCCs), strong staining was observed with great compatibility. High COX-2 detectability throughout the entire tumor mass could be helpful in the finding of SCC cells. However, in basal cell carcinomas, and precancerous lesions, frequency and detection level of this protein, as well as the type and/or localization of stained cells within the tumor, varied among different research groups. The discrepancies may be due to the heterogeneity of each of these 2 groups of lesions. However, differences in COX-2 staining in normal skin indicate also possible methodological reasons. In general, COX-2 levels were significantly decreased in basal cell carcinomas compared with SCCs, which could be used in the differential diagnosis of these cancers. Reduced, although heterogenous, COX-2 expression in precancerous lesions may suggest its association with SCC development. These observations are consistent with data on the efficacy of preventive and therapeutic effects of nonsteroidal anti-inflammatory drugs that are COX-2 inhibitors.

European interdisciplinary guideline on invasive squamous cell carcinoma of the skin: Part 1. epidemiology, diagnostics and prevention

Invasive cutaneous squamous cell carcinoma (cSCC) is one of the most common cancers in the white populations, accounting for 20% of all cutaneous malignancies. Factors implicated in cSCC etiopathogenesis include ultraviolet radiation exposure and chronic photoaging, age, male sex, immunosuppression, smoking and genetic factors. A collaboration of multidisciplinary experts from the European Dermatology Forum (EDF), the European Association of Dermato-Oncology (EADO) and the European Organisation of Research and Treatment of Cancer (EORTC) was formed to update recommendations on cSCC classification, diagnosis, risk stratification, staging and prevention, based on current literature, staging systems and expert consensus. Common cSCCs are typically indolent tumors, and most have a good prognosis with 5-year cure rates of greater than 90%, and a low rate of metastases (<4%). Further risk stratification into low-risk or high-risk common primary cSCC is recommended based on proposed high-risk factors. Advanced cSCC is classified as locally advanced (lacSCC), and metastatic (mcSCC) including locoregional metastatic or distant metastatic cSCC. Current systems used for staging include the American Joint Committee on Cancer (AJCC) 8th edition, the Union for International Cancer Control (UICC) 8th edition, and Brigham and Women's Hospital (BWH) system. Physical examination for all cSCCs should include total body skin examination and clinical palpation of lymph nodes, especially of the draining basins. Radiologic imaging such as ultrasound of the regional lymph nodes, magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography-computed tomography (PET-CT) scans are recommended for staging of high-risk cSCC. Sentinel lymph node biopsy is currently not recommended. Nicotinamide, oral retinoids, and topical 5-FU have been used for the chemoprevention of subsequent cSCCs in high-risk patients but are not routinely recommended. Education about sun protection measures including reducing sun exposure, use of protective clothing, regular use of sunscreens and avoidance of artificial tanning, is recommended.

Malignant Transformation in Diabetic Foot Ulcers-Case Reports and Review of the Literature

An imbalance of regeneration and destruction of the extracellular matrix due to a plethora of chemo- and cytokines, elevated matrix metalloproteinases, bacterial contamination and repetitive painless tissue damage can lead the chronicity of a wound, especially in diabetic foot ulcers (DFU). Along general lines, wound healing and cancer development are similar. Therefore chronic wounds prepare a breeding ground for cancer development. Several characteristics such as increase in size, verrucous everted margins and contact bleeding are suspicious for malignant growth in a chronic wound. While previously the term Marjolin's ulcer was attributed to a malignant tumor in (burn) scars, it is nowadays used for every malignant tumor in chronic wounds. Furthermore, chronic ulcers in diabetic feet are susceptible for malignant transformation. We describe two cases of squamous cell carcinoma in patients with DFU-a 71 year-old woman and a 67 year old man. Both received total tumor excision and split-skin grafts with good short-time results.

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.

In-vitro Anti-proliferative Effects of Ethanolic Extract of Vanilla Planifolia Leaf Extract against A431 Human Epidermoid Carcinoma Cells

Squamous cell carcinoma is the second largest among skin cancer diseases. The aim of the present study is to reveal the antiproliferative property of vanilla leaf extract against A431 cells. Antiproliferative property was assessed by MTT assay. Apoptotic property was assessed by DNA fragmentation assay. Antiproliferative property of extract was revealed in a dose dependent manner. IC50 of the extract against A431 cells was revealed at 31.2µg/ml. This study revealed the cancer suppression capability of vanilla leaf extract in skin cancer cell lines.

Recurrent aphthous stomatitis may be a precursor or risk factor for specific cancers: A case-control frequency-matched study

BACKGROUND

Recurrent aphthous stomatitis (RAS) is considered a prophase symptom in patients with specific cancers. This study assessed the association between RAS and subsequent onset of cancer based on a nationwide population-based database in Taiwan.

MATERIALS AND METHODS

We selected study participants from the National Health Insurance Research Database from January 2000 to December 2008. Patients in the non-RAS cohort were matched to case study patients at a 1:1 ratio through frequency matching. All participants were followed up for at least 5 years, and those who received cancer diagnoses during follow-up were identified.

RESULTS

Among 52 307 patients with and 52 304 patients without RAS, the combined hazard ratio (HR) of all subsequent cancer cases was 1.3 (95% confidence interval [CI]: 1.25-1.35, P = 0). RAS diagnosis was associated with risk for cancers of the head and neck (aHR = 2, 95% CI: 1.8-2.3), colon (aHR = 1.2, 95% CI: 1.1-1.4), liver (aHR = 1.1, 95% CI: 1-1.3), pancreas (aHR = 1.4, 95% CI: 1.1-1.7), skin (aHR = 1.4, 95% CI: 1.2-1.7), breast (aHR = 1.2, 95% CI: 1.1-1.4), and prostate (aHR = 1.5, 95% CI: 1.3-1.8), as well as hematologic cancers (aHR = 1.6, 95% CI: 1.3-1.9). A higher risk was observed for male patients (aHR = 1.35, 95% CI: 1.28-1.42) than for female patients (aHR = 1.25, 95% CI: 1.18-1.31) with RAS.

CONCLUSIONS

RAS was associated with specific cancers. Susceptible RAS patients should be screened for specific cancers.

Cancer: the dark side of wound healing

Complex multicellular organisms have evolved sophisticated mechanisms to rapidly resolve epithelial injuries. Epithelial integrity is critical to maintaining internal homeostasis. An epithelial breach represents the potential for pathogen ingress and fluid loss, both of which may have severe consequences if not limited. The mammalian wound healing response involves a finely tuned, self-limiting series of cellular and molecular events orchestrated by the transient activation of specific signalling pathways. Accurate regulation of these events is essential; failure to initiate key steps at the right time delays healing and leads to chronic wounds, while aberrant initiation of wound healing processes may produce cell behaviours that promote cancer progression. In this review, we discuss how wound healing pathways co-opted in cancer lose their stringent regulation and become compromised in their reversibility. We hypothesize on how the commandeering of wound healing 'master regulators' is involved in this process, and also highlight the implications of these findings in the treatment of both chronic wounds and cancer.

Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies

Background

Epidemiological studies have clarified the potential associations between regular aspirin use and cancers. However, it remains controversial on whether aspirin use decreases the risk of cancers risks. Therefore, we conducted an updated meta-analysis to assess the associations between aspirin use and cancers.

Methods

The PubMed, Embase, and Web of Science databases were systematically searched up to March 2017 to identify relevant studies. Relative risks (RRs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

Results

A total of 218 studies with 309 reports were eligible for this meta-analysis. Aspirin use was associated with a significant decrease in the risk of overall cancer (RR = 0.89, 95% CI: 0.87–0.91), and gastric (RR = 0.75, 95% CI: 0.65–0.86), esophageal (RR = 0.75, 95% CI: 0.62–0.89), colorectal (RR = 0.79, 95% CI: 0.74–0.85), pancreatic (RR = 0.80, 95% CI: 0.68–0.93), ovarian (RR = 0.89, 95% CI: 0.83–0.95), endometrial (RR = 0.92, 95% CI: 0.85–0.99), breast (RR = 0.92, 95% CI: 0.88–0.96), and prostate (RR = 0.94, 95% CI: 0.90–0.99) cancers, as well as small intestine neuroendocrine tumors (RR = 0.17, 95% CI: 0.05–0.58).

Conclusions

These findings suggest that aspirin use is associated with a reduced risk of gastric, esophageal, colorectal, pancreatic, ovarian, endometrial, breast, and prostate cancers, and small intestine neuroendocrine tumors.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4156-5) contains supplementary material, which is available to authorized users.

Alleviating Promotion of Inflammation and Cancer Induced by Nonsteroidal Anti-Inflammatory Drugs

Clinical Relevance

Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) including aspirin are of intensive use nowadays. These drugs exert their activity via the metabolism of arachidonic acid (AA) by cyclooxygenase inhibition. Though beneficial for health in some instances, both unspecific and specific cyclooxygenase inhibitor activity interfere with AA metabolism producing also proinflammatory lipids that may promote cancer.

Materials and Methods

This review is based on available literature on clinical uses, biochemical investigations, molecular medicine, pharmacology, toxicity, and epidemiology-clinical studies on NSAIDs and other drugs that may be used accordingly, which was collected from electronic (SciFinder, Medline, Science Direct, and ACS among others) and library searches of books and journals.

Results

Relevant literature supports the notion that NDSAID use may also promote proinflammatory biochemical events that are also related to precancerous predisposition. Several agents are proposed that may be employed in immediate future to supplement and optimize treatment with NSAIDs. In this way serious side effects arising from promotion of inflammation and cancer, especially in chronic NSAID users and high risk groups of patients, could be avoided.

Diet phytochemicals and cutaneous carcinoma chemoprevention: A review

Cutaneous carcinoma, which has occupied a peculiar place among worldwide populations, is commonly responsible for the considerably increasing morbidity and mortality rates. Currently available medical procedures fail to completely avoid cutaneous carcinoma development or to prevent mortality. Cancer chemoprevention, as an alternative strategy, is being considered to reduce the incidence and burden of cancers through chemical agents. Derived from dietary foods, phytochemicals have become safe and reliable compounds for the chemoprevention of cutaneous carcinoma by relieving multiple pathological processes, including oxidative damage, epigenetic alteration, chronic inflammation, angiogenesis, etc. In this review, we presented comprehensive knowledges, main molecular mechanisms for the initiation and development of cutaneous carcinoma as well as effects of various diet phytochemicals on chemoprevention.

Chemopreventive opportunities to control basal cell carcinoma: Current perspectives

Basal cell carcinoma (BCC) is a major health problem with approximately 2.8 million new cases diagnosed each year in the United States. BCC incidences have continued to rise due to lack of effective chemopreventive options. One of the key molecular characteristics of BCC is the sustained activation of hedgehog signaling through inactivating mutations in the tumor suppressor gene patch (Ptch) or activating mutations in Smoothened. In the past, several studies have addressed targeting the activated hedgehog pathway for the treatment and prevention of BCC, although with toxic effects. Other studies have attempted BCC chemoprevention through targeting the promotional phase of the disease especially the inflammatory component. The compounds that have been utilized in pre-clinical and/or clinical studies include green and black tea, difluoromethylornithine, thymidine dinucleotide, retinoids, non-steroidal anti-inflammatory drugs, vitamin D3, and silibinin. In this review, we have discussed genetic and epigenetic modifications that occur during BCC development as well as the current state of BCC pre-clinical and clinical chemoprevention studies.

Wnt/β-Catenin Signaling Pathway in Skin Carcinogenesis and Therapy

Cooperating with other signaling pathways, Wnt signaling controls cell proliferation, morphology, motility, and embryonic development destination and maintains the homeostasis of tissues including skin, blood, intestine, and brain by regulating somatic stem cells and their niches throughout adult life. Abnormal regulation of Wnt pathways leads to neoplastic proliferation in these tissues. Recent research shows that Wnt signaling is also associated with the regulation of cancer stem cells (CSCs) through a similar mechanism to that observed in normal adult stem cells. Thus, the Wnt/β-catenin signaling pathway has been intensively studied and characterized. For this review, we will focus on the regulation of the Wnt/β-catenin signaling pathway in skin cancer. With the important role in stemness and skin CSC proliferation, the Wnt/β-catenin signaling pathway and its elements have the potential to be targets for skin cancer therapy.

An Overview of Ultraviolet B Radiation-Induced Skin Cancer Chemoprevention by Silibinin

Skin cancer incidences are rising worldwide, and one of the major causative factors is excessive exposure to solar ultraviolet radiation (UVR). Annually, ~5 million skin cancer patients are treated in United States, mostly with nonmelanoma skin cancer (NMSC), which is also frequent in other Western countries. As sunscreens do not provide adequate protection against deleterious effects of UVR, additional and alternative chemoprevention strategies are urgently needed to reduce skin cancer burden. Over the last couple of decades, extensive research has been conducted to understand the molecular basis of skin carcinogenesis, and to identifying novel agents which could be useful in the chemoprevention of skin cancer. In this regard, several natural non-toxic compounds have shown promising efficacy in preventing skin carcinogenesis at initiation, promotion and progression stages, and are considered important in better management of skin cancer. Consistent with this, we and others have studied and established the notable efficacy of natural flavonolignan silibinin against UVB-induced skin carcinogenesis. Extensive pre-clinical animal and cell culture studies report strong anti-inflammatory, anti-oxidant, DNA damage repair, immune-modulatory and anti-proliferative properties of silibinin. Molecular studies have identified that silibinin targets pleotropic signaling pathways including mitogenic, cell cycle, apoptosis, autophagy, p53, NF-κB, etc. Overall, the skin cancer chemopreventive potential of silibinin is well supported by comprehensive mechanistic studies, suggesting its greater use against UV-induced cellular damages and photocarcinogenesis.