Role of COX-2 activity and CRP levels in patients with non-melanoma skin cancer. ?765G>C PTGS2 polymorphism and NMSC risk

Non-melanoma skin cancer is one of the most common of all cancers and the incidence has increased in the last years as a result of many factors including increased tanning, life style and possible global climate change. Inflammation plays an important role in cancer development and is frequently evaluated by serum C-reactive protein (CRP) levels. PTGS2 -765C allele coding for COX-2 has been found to be associated with lower plasma levels of CRP. The objectives of this study are: evaluation of the association between PTGS2 -765G>C polymorphism and the occurrence of non-melanoma skin cancer, the relationship between this polymorphism and cyclooxygenase-2 activity in skin tissue, as well as the correlation with serum CRP levels in patients with non-melanoma skin cancer. We used PCR-RFLP technique to explore -765G>C PTGS2 gene polymorphism, colorimetric analysis for cyclooxygenase-2 activity in skin tissue and immunoturbidimetric assay for CRP serum levels in 174 patients with non-melanoma skin cancer [54 patients with basal cell carcinoma (BCC) and 120 patients with squamous cell carcinoma (SCC)] and 80 healthy subjects. PTGS2 -765G>C polymorphism failed to show an association with non-melanoma skin cancer risk. We observed a significant increase in COX-2 activity in SCC and BCC patients compared to control tissue (0.58 ± 0.11 and 0.63 ± 0.09 U/mg protein, respectively vs. 0.16 ± 0.01 U/mg protein). BCC and SCC intra-group analysis showed lower COX-2 activity in C-allele carriers versus non-carriers (p < 0.001 and p < 0.0001, respectively). In BCC and SCC patients with GG genotype, CRP level is significantly increased compared to control group (p < 0.0001 and p < 0.0001, respectively). Intra-group comparison of CRP levels showed significantly lower CRP levels in patients carrying C-allele compared to GG homozygotes in BCC (p = 0.0001) and SCC patients (p < 0.0001). PTGS2 -765G>C polymorphism failed to show an association with non-melanoma skin cancer risk. Regarding prognostic indicators, no consistent association emerged between PTGS2 -765G>C polymorphism and COX-2 activity or CRP levels.     

Association of promoter polymorphism −765G>C in the PTGS2 gene with malignant melanoma in Italian patients and its correlation to gene expression in dermal fibroblasts

Prostaglandins, especially prostaglandin E synthetase (PGE2), influence carcinogenesis by promoting cell proliferation, inhibiting apoptosis, stimulating angiogenesis and mediating immune suppression. Cyclooxygenase‐2, coded by the PTGS2 gene, is the key enzyme in the production of prostaglandins. In melanoma, Cox‐2 is over expressed in primary malignant melanoma (MM) and in their corresponding metastases. Polymorphisms in the promoter region of PTGS2 gene can modulate gene expression and could modify individual susceptibility to MM. Two hundred and forty melanoma patients and 342 controls were genotyped for polymorphisms ?765G>C (rs20417) and ?1195A>G (rs689466). Allele ?765C frequency was significantly higher in melanoma patients. No allele frequency differences for ?1195A>G polymorphism were observed. Haplotype analysis revealed that the haplotypes carrying the minor alleles were associated to a higher risk of melanoma (P = 0.02). Expression analysis showed that allele ?765C is associated to a higher gene expression and could represent a risk allele by affecting the functionality of the promoter.     

Analysis of the 3'UTR of the prostaglandin synthetase-2 (PTGS-2/COX-2) gene in non-melanoma skin cancer after organ transplantation

To define the potential involvement of polymorphisms in the 3'untranslated region (3'UTR) of the prostaglandin synthetase-2 (PTGS-2) gene to non-melanoma skin cancer (NMSC) predisposition after transplantation, we screened for genetic variant, relevant parts of this region. It contains binding sites for trans-acting factors, an alternative polyadenylation site and putative target sequences for miRNAs. Variant +8473T>C did not appear to play a functional role in the regulation of gene expression in human keratinocyte-transfected cells. In addition to the well-known +8473T>C, we identified four polymorphisms: +8293G>C, +10259T>G, +10267G>A and +10335G>A. No allele frequency differences were observed between cases and controls neither for +8473T>C nor for any of the identified polymorphisms, suggesting that polymorphisms in the 3'UTR of the PTGS2 gene are rare and unlikely to represent risk factor for NMSC after transplantation.     

Glutathione S-transferase and CYP1A1 gene polymorphisms and non-melanoma skin cancer risk in Italian transplanted patients

Solid organ transplant recipients are at higher risk of non-melanoma skin cancer (NMSC), especially basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Genetic alterations in the production of detoxifying enzymes such as glutathione S-transferase (GST) and CYP1A1 may enhance this risk. We investigated the frequency of GST genotypes (GSTM1, GSTM3, GSTT1 and GSTP1) and CYP1A1 in 239 transplant recipients: 107 cases with NMSC and 132 controls free from NMSC matched for type of transplanted organ, duration of transplantation, sex and age. Allele GSTP1*A was associated with a higher risk of NMSC [odds ratio (OR) 1.7 (1.1-2.5); P = 0.017]. Homozygosity for allele GSTP1 Val(105) was lower in cases [OR 0.3 (0.1-0.8); P = 0.012], especially in patients with SCC [OR 0.1 (0.0-0.7); P = 0.012]. A higher risk of BCC was found in patients with GSTM1 null/null [null/null versus A + B, OR 3.1 (1.4-6.8); P = 0.003]. Analysis of allelism and interaction between allelic variants showed significant association between combined GSTM1 and CYP1A1 Val(462) genotypes, where individuals homozygous for the risk allele GSTM1 null and carrying also the allele CYP1A1 Val(462), show a higher risk of developing NMSC [OR 4.5 (1.1-21.4); P = 0.03], especially SCC [OR 6.5 (1.4-34.4); P = 0.01]. GSTP1 polymorphisms are associated with both BCC and SCC risk. GSTM1 polymorphisms seem to be involved in BCC risk, while GSTM1 null/null genotype combined with CYP1A1 allele Val(462) are associated with a higher risk for SCC, indicating that allelism and/or interactions between allelic variants at other loci may also influence the risk of NMSC, particularly SCC.     

Survivin和COX-2在皮肤基底细胞癌和鳞状细胞癌组织中的表达及相关性

目的了解皮肤基底细胞癌和皮肤鳞状细胞癌中Survivin和COX-2的表达情况及两者的关系。方法采用免疫组化法检测10例正常对照组、23例基底细胞癌、18例鳞状细胞癌组织中Survivin和COX-2的表达情况。结果 Survivin蛋白在正常组织中不表达,基底细胞癌和鳞状细胞癌中Survivin蛋白的表达率分别为60.87%和66.67%。COX-2在正常组织中的表达率为10%,基底细胞癌和鳞状细胞癌中COX-2的表达率分别为65.22%和66.67%,且明显高于其在正常组织中的表达率。Survivin的表达和COX-2的表达呈显著正相关(P0.05)。结论 Survivin蛋白和COX-2在皮肤基底细胞癌和皮肤鳞状细胞癌中高表达,两者呈正相关。     

PTCH1 gene haplotype association with basal cell carcinoma after transplantation

Background Basal cell carcinoma (BCC) is 10 times more frequent in organ transplant recipients (OTRs) than in the general population. Factors in OTRs conferring increased susceptibility to BCC include ultraviolet radiation exposure, immunosuppression, viral infections such as human papillomavirus, phototype and genetic predisposition. The PTCH1 gene is a negative regulator of the hedgehog pathway, that provides mitogenic signals to basal cells in skin. PTCH1 gene mutations cause naevoid BCC syndrome, and contribute to the development of sporadic BCC and other types of cancers. Associations have been reported between PTCH1 polymorphisms and BCC susceptibility in nontransplanted individuals. Objectives To search for novel common polymorphisms in the proximal 5′ regulatory region upstream of PTCH1 gene exon 1B, and to investigate the possible association of PTCH1 polymorphisms and haplotypes with BCC risk after organ transplantation. Methods Three PTCH1 single nucleotide polymorphisms (rs2297086, rs2066836 and rs357564) were analysed by restriction fragment length polymorphism analysis in 161 northern Italian OTRs (56 BCC cases and 105 controls). Two regions of the PTCH1 gene promoter were screened by heteroduplex analysis in 30 cases and 30 controls. Results Single locus analysis showed no significant association. Haplotype T₁₆₈₆–T₃₉₄₄ appeared to confer a significantly higher risk for BCC development (odds ratio 2·98, 95% confidence interval 2·55–3·48; P = 0·001). Two novel rare polymorphisms were identified at positions 176 and 179 of the 5′UTR. Two novel alleles of the ‐4 (CGG)_n microsatellite were identified. No association of this microsatellite with BCC was observed. Conclusions Haplotypes containing T₁₆₈₆–T₃₉₄₄ alleles were shown to be associated with an increased BCC risk in our study population. These data appear to be of great interest for further investigations in a larger group of transplant individuals. Our results do not support the hypothesis that common polymorphisms in the proximal 5′ regulatory region of the PTCH1 gene could represent an important risk factor for BCC after organ transplantation.     

Differential expression of E prostanoid receptors in murine and human non-melanoma skin cancer

Enhanced prostaglandin production via upregulated cyclooxygenase-2 (COX-2) expression is a likely contributing factor in ultraviolet B (UVB)-induced non-melanoma skin cancer (NMSC), which consists primarily of squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). The four E prostanoid (EP) receptors, designated EP1 through EP4, are known to bind prostaglandin E2 (PGE2), the major prostaglandin present in the skin. We used murine models of UVB-induced SCC and BCC, as well as human NMSC from sun-exposed sites, to investigate the expression of EP receptors during UVB-induced tumorigenesis. We observed that UVB-induced murine SCC are associated with markedly altered expression patterns of the EP receptors when compared with non-irradiated skin. In contrast, expression of all EP receptors was largely absent in UVB-induced murine BCC. We also observed expression of all four EP receptors in human SCC, with altered expression of their mRNA levels as compared with adjacent tumor-free skin. Consistent with our murine studies, no EP receptor expression was detected in human BCC, and their mRNA expression levels showed no change from the adjacent non-tumor-bearing skin. These data suggest that altered EP receptor expression may play a differential role in the development of UVB-induced SCC and BCC in murine and human skin.     

A randomized, 12-year primary-prevention trial of beta carotene supplementation for nonmelanoma skin cancer in the physician's health study

CONTEXT: Although basic research provides plausible mechanisms for benefits of beta carotene supplementation on nonmelanoma skin cancer (NMSC) primarily consisting of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), observational studies are inconsistent. Randomized trial data are limited to 1 trial of secondary prevention that showed no effect of beta carotene on the incidence of NMSC after 5 years. OBJECTIVE: To test whether supplementation with beta carotene reduces the risk for development of a first NMSC, including BCC and SCC. DESIGN: Randomized, double-blind, placebo-controlled trial with 12 years of beta carotene supplementation and follow-up. SETTING: Physicians' Health Study in the United States. PARTICIPANTS: Apparently healthy male physicians aged 40 to 84 years in 1982 (N = 22 071). INTERVENTION: Beta carotene, 50 mg, on alternate days. MAIN OUTCOME MEASURE: Relative risk (RR) and 95% confidence interval (CI) for a first NMSC, BCC, and SCC. RESULTS: After adjusting for age and randomized aspirin assignment, there was no effect of beta carotene on the incidence of a first NMSC (RR, 0.98; 95% CI, 0.92-1.05), BCC (RR, 0.99; 95% CI, 0.92-1.06), or SCC (RR, 0.97; 95% CI, 0.84-1.13). There was also no significant evidence of beneficial or harmful effects of beta carotene on NMSC by smoking status (current, past, or never). CONCLUSION: This large-scale, randomized, primary prevention trial among apparently healthy well-nourished men indicates that an average of 12 years of supplementation with beta carotene does not affect the development of a first NMSC, including BCC and SCC.     

Immunohistochemical study of cyclooxygenase-2 and p53 expression in skin tumors

Overexpression of cyclooxygenase-2 (COX-2) has been demonstrated in various cancers, including experimentally promoted tumors, gastrointestinal cancers, breast tumors and skin tumors. The mechanism that controls COX-2 expression is not yet clear. Currently, it is reported that COX-2 expression is frequently associated with mutated p53 genes. The goal of this study was to evaluate the expression patterns of COX-2 and p53 in several skin tumors and their correlation. An immunohistochemical method was used to investigate the expression of COX-2 and p53 proteins on formalin-fixed, paraffin-embedded tissue specimens of squamous cell carcinomas (SCC), basal cell carcinomas (BCC), Bowen's disease (BD), actinic keratosis (AK) and porokeratosis. The expression of COX-2 increased in 50% (5/10) of SCC, 80% (8/10) of BCC, 40% (4/10) of BD, 50% (5/10) of AK, and 20% (2/10) of porokeratosis cases. The expression of p53 increased in 90% (9/10) of SCC, 70% (7/10) of BCC, 70% (7/10) of BD, 50% (5/10) of AK, and 40% (4/10) of porokeratosis cases. COX-2 positivity rates of the p53-positive skin tumors were 56%, 100%, 57%, 80% and 25% in SCC, BCC, BD, AK and porokeratosis, respectively. However, the correlation between p53 and COX-2 expression in skin tumors was not statistically significant ( P  > 0.05). Our results indicate that skin COX-2 and p53 may play roles in skin tumors, but that there is no apparent correlation between the two markers.     

Positivity for HLA DR1 is associated with basal cell carcinoma in renal transplant patients in southern Brazil

Background Renal transplant patients have a higher incidence of non‐melanoma skin cancer (NMSC). Previous studies hypothesized that human leukocyte antigen (HLA), especially types DR1, DR4, and DR7, may influence the incidence of these tumors. This study investigates the association between NMSC and the presence of HLA DR1, DR4, and DR7 in renal transplant patients in southern Brazil. Methods In a historical cohort study, 1032 patients who underwent renal transplantation during the period from January 1993 to December 2006 were examined to identify occurrences of NMSC and HLA status prior to transplant. Results Of the 1032 patients examined, 59 (5.71%) developed NMSC (squamous cell carcinoma [SCC]: 2.42%; basal cell carcinoma [BCC]: 1.74%; both: 1.55%). The presence of HLA DR1 was associated with a higher probability of developing any NMSC and particularly with developing BCC (P < 0.05). There was no statistically significant association between the presence of HLA DR4 or DR7 and the occurrence of NMSC in this sample. Conclusions HLA DR1 appears to be associated with the development of BCC, as well as with the higher number of NMSC lesions in renal transplant patients. This study supports the trend to associate the DR1 allele with BCC and not with SCC.     

Nonmelanoma skin cancer after renal transplantation: a single-center experience in 1736 transplantations

Background Renal transplantation is associated with an increased incidence of nonmela‐noma skin cancer (NMSC) caused by immunosuppression. Squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), the two major histological types of NMSC, exhibit more aggressive biological and clinical courses in renal transplant recipients (RTRs), with higher rates of recurrence and mortality than in the general population. Methods We retrospectively analyzed our experience of NMSC in 1736 renal transplantations performed over a 25‐year period. All cases of skin cancer after renal transplantation were included except those of skin cancer resulting from melanoma and mesenchymal skin tumors. Results In our series, the overall incidence of NMSC after transplantation was 2.2% (n = 39), and SCC represented the most frequent skin malignancy (64.1%), followed by BCC (17.9%), Bowen’s disease (10.2%), basosquamous carcinoma (5.1%), and a rare case of invasive sebaceous carcinoma (2.6%). A shift to newer immunosuppressive regimens after the initial diagnosis of NMSC had been implemented in eight cases (20.5%). The recurrence rate after initial treatment was 41% (n = 16), and distant metastatic disease was diagnosed in 15.4% (n = 6) of NMSC patients. The NMSC‐specific mortality rate was 25.6% (n = 10). Conclusions Nonmelanoma skin cancer remains a significant source of morbidity and mortality in RTRs, and post‐transplant surveillance should be increased.     

环氧合酶-2在皮肤肿瘤组织中的表达及其临床意义

目的　探讨环氧合酶 2 (COX 2 )在皮肤肿瘤组织中的表达及其临床意义。方法　应用免疫组织化学方法分别检测 82例皮肤肿瘤组织 ( 2 1例Bowen病、2 6例基底细胞癌、3 5例鳞状细胞癌 )和 10例正常皮肤组织中COX 2的表达。结果　皮肤肿瘤组织中COX 2阳性表达率为 76.83 % ,显著高于正常皮肤组织的 10 .0 0 % ( χ2 =15 .78,P <0 .0 1) ;COX 2主要表达于肿瘤细胞胞浆与核周 ;鳞状细胞癌的阳性表达与肿瘤分期无明显相关 ( χ2 =0 .70 ,P >0 .0 5 )。结论　COX 2的高表达可能与皮肤肿瘤的发生有关     

环氧化酶-2在表皮肿瘤中的表达

目的 探讨环氧化酶-2在不同表皮肿瘤中的表达及意义。方法 选择鳞状细胞癌8例、基底细胞上皮瘤10例、Bowen病8例和脂溢性角化病12例,运用免疫组化方法观察肿瘤细胞中环氧化酶-2的表达。结果 与正常表皮相比,环氧化酶-2在鳞状细胞癌、Bowen病、基底细胞上皮瘤中的表达明显上调,尤其以鳞状细胞癌中的表达最强。而环氧化酶-2在脂溢性角化病中的表达与正常人皮肤的表达近似。结论 环氧化酶-2表达的上调可能在表皮肿瘤的发生发展中发挥一定作用。     

Risk of developing a subsequent nonmelanoma skin cancer in patients with a history of nonmelanoma skin cancer: a critical review of the literature and meta-analysis

OBJECTIVE: To assess the risk of developing a basal cell carcinoma (BCC), and/or a squamous cell carcinoma (SCC), and/or Bowen disease (SCC in situ) after a nonmelanoma skin cancer (NMSC) of a specific type. DATA SOURCES: Four electronic databases were searched from January 1, 1966, to October 21, 1999. STUDY SELECTION: We included all studies published in English, identified by standard search strategies, that provided original data quantifying the risk of an NMSC among persons with a previous NMSC. DATA EXTRACTION: For each study and separate histological type of index skin tumor and subsequent skin tumor (SCC, BCC, NMSC, or Bowen disease), we determined the 3-year cumulative risk and the incidence rate of second tumors per 100 000 person-years. In cases where more than 1 study was assessing the risk of one specific tumor type after another, we undertook a formal meta-analysis. We compared the incidence of a subsequent SCC after an index SCC and of a subsequent BCC after an index BCC with the incidence of the first occurrence of such tumors in the comparable general population. DATA SYNTHESIS: We identified and reviewed 17 studies that included data for 26 tumor combinations. Overall, the 3-year cumulative risk of a subsequent SCC after an index SCC is 18%, at least a 10-fold increase in incidence compared with the incidence of first tumors in a comparable general population. For BCCs, the 3-year cumulative risk is 44%, also at least a 10-fold increase in incidence compared with the rate in a comparable general population. The risk of developing a BCC in patients with a prior SCC is about equal to that risk among persons with a prior BCC, but the risk of developing an SCC in patients with a prior BCC is low (6%). CONCLUSIONS: Although these studies vary in their study type, location, and biases, their results are consistent. The risk of developing a subsequent skin cancer of a specific type depends on the type of prior NMSC and number of prior skin tumors of that type. Based on these findings, follow-up strategies for patients with BCC and SCC are suggested.     

Non-melanoma skin cancer risk in the Queensland renal transplant population

BACKGROUND: Non-melanoma skin cancer (NMSC) is an important complication of solid organ transplantation, especially in areas of high ultraviolet light exposure. Registry data may underestimate the scale of the problem. OBJECTIVES: A single-observer study of a Queensland renal transplant population was conducted between July 1999 and April 2000 utilizing both cross-sectional and retrospective data. The aims were to determine accurately the risk of NMSC following renal transplantation and compare this with currently available registry data. PATIENTS AND METHODS: A structured interview and full skin examination was completed by 398 renal transplant recipients. Case notes and histology reports were examined for details of previous skin tumours. Independently collected data on 341 subjects from the Australia and New Zealand Dialysis and Transplantation Registry (ANZDATA) were also examined. RESULTS: One hundred and eighty-seven of 361 (51.8%) transplant recipients of Fitzpatrick skin types I-IV had developed 3979 histologically diagnosed NMSCs since first transplantation. The ratio of SCC/BCC was reversed from 1 : 3.7 before transplantation to 2 : 1 after transplantation. NMSC increased with duration of immunosuppression; 29.1%, 52.2%, 72.4% and 82.1% of those immunosuppressed for < 5, 5-10, 10-20 and > 20 years, respectively, had developed at least one tumour. The ANZDATA registry under-recorded the numbers of patients with NMSC by 28.4% and gave no indication of tumour numbers. CONCLUSIONS: NMSC is a greater clinical problem in renal transplant recipients living in subtropical Queensland, Australia, than is shown by currently available registry data. This has implications for the development of prevention and surveillance strategies.     

Association of COX2 functional polymorphisms and the risk of vitiligo in Chinese populations

BackgroundCyclooxygenase-2 (COX2) plays an important role in the production of prostaglandin E2 (PGE2), which is made by epidermal keratinocytes in response to ultraviolet radiation (UVR). PGE2 is important for the proliferation and melanogenesis of epidermal melanocytes, the loss of which leads to vitiligo. COX2-1195A > G, -765G > C, and -8473T > C polymorphisms may influence the mRNA levels of COX2 and affect the production of PGE2 subsequently. Therefore, we supposed that these polymorphisms may be associated with vitiligo.ObjectiveThe aim of the study was to elucidate the association between three functional COX2 polymorphisms and the risk of vitiligo.MethodsThis was a hospital-based, case–control study of 755 vitiligo patients and 774 vitiligo-free controls who were frequency matched by age and sex. We genotyped COX2-1195A > G, -765G > C, and -8473T > C polymorphisms by using PCR-restriction fragment length polymorphism (RFLP) method and assessed their respective associations with the risk of vitiligo in Han Chinese populations.ResultsWe found a statistically significant increased risk of vitiligo to be associated with the COX2-1195 G variant allele (p = 0.004). Significantly higher vitiligo risks were found among subgroups with these characteristics: age >20 years, male, active, nonsegmental vitiligo, and onset age >20 years. In addition, the interaction between COX2-1195 and COX2-8473 was statistically significant (p = 0.004).ConclusionFor the first time, we provide evidence that functional polymorphisms in the COX2 gene may influence the risk of vitiligo in Han Chinese populations, suggesting new clues that help to clarify the pathogenesis of vitiligo. Larger studies are needed to verify these findings.     

Human papillomavirus status in extragenital nonmelanoma skin cancers

About 5% of all cancers worldwide can be attributed to human papillomaviruses (HPVs); namely, six sites are strongly associated with HPV infections: cervix, penis, vulva, vagina, anus, and oropharynx. Nonmelanoma skin cancers (NMSC), basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) are the most common malignancies in Caucasians. In fact, there is an intense connection between sunlight exposure, fair skin, HPV, and development of NMSC. We have conducted a pilot study that included tissue samples from 26 carcinoma patients, of which there were 13 BCC and 13 SCC. HPV detection and typing was done with DNA amplification and sequencing, respectively. In total, 23.1% of SCC samples (3/13) and 7.7% of BCC samples (1/13) were positive for HPV DNA. The importance of understanding all aspects of NMSC carcinogenesis may be to reveal novel therapeutic options or preventive measures for HPV containing NMSC patients.     

The Epidemiology of Non-Melanoma Skin Cancer: Who,Why and What Can We Do about It

Non-melanoma skin cancer (NMSC) comprised of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common cancers in humans in many countries. Sunlight plays a major part in the development of these tumours which appear predominantly on areas of the most frequently exposed skin. The site distribution for BCC and SCC is not the same, with SCC being most common on the sites of very heavy exposure and BCC becoming more common on areas of only moderate exposure, e.g. upper trunk in men and women and lower leg in women. Incidence rates of NMSC, where they are being recorded, show rises over time. Mortality rates, on the other hand, have been dropping most of this century until they have been levelling out recently. The case fatality rate due to SCC appears to be between 1–2%. The malignant transformation rate of actinic keratoses to SCC appears to be very low. Studies on similar populations at different latitudes allow estimates to be made of increases which might occur with increasing exposure to ultraviolet radiation (UVR) over a life time. These have been used to estimate the possible increases in NMSC due to stratospheric ozone depletion. Finally, recent studies on the reduction of existing actinic keratoses and prevention of new ones with regular use of sunscreen augurs well for prevention of NMSC in the future.