Environment, phenotype and genetics: risk factors associated with BCC of the skin

Risk of Melanoma in Patients with Basal Cell Carcinoma: A Population-based Cohort Study

Basal cell carcinoma is the most prevalent cancer in Caucasians worldwide. The aim of this study was to examine the overall risk of melanoma among patients diagnosed with basal cell carcinoma. This population-based retrospective cohort study included data from January 2010 to December 2018 from the databases of the Clalit Health Maintenance Organization and 2 major pathology laboratories in North District, Israel. The incidence and hazard ratio of melanoma in patients with a diagnosis of basal cell carcinoma were determined. Of 466,700 participants, 51% were women and the mean (standard deviation) follow-up was 6.7 (2.9; range 1-9) years. A total of 3,338 patients were diagnosed with basal cell carcinoma during the study period, 82 of whom subsequently developed melanoma. Patients with basal cell carcinoma had a significantly higher incidence of melanoma than patients without basal cell carcinoma (2.46% vs 0.37%; p < 0.0001). Univariate Cox regression analysis revealed a hazard ratio of 6.6 (95% confidence interval: 3.6-12.1; p < 0.0001) for melanoma in patients with a diagnosis of basal cell carcinoma. In conclusion, a diagnosis of basal cell carcinoma confers a significant risk of melanoma.

"Basal cell carcinoma of the hand: A systematic review and meta-analysis of incidence of recurrence"

Background

Hand basal cell carcinoma is a rare and complex disorder. Due to the hand's anatomical features, managing hand BCC is challenging. Therefore, we have conducted this systematic review to investigate various clinical characteristics, investigations, and treatment options related to hand BCC. Furthermore, a meta-analysis was used to provide pooled recurrence rates.

Methods

We conducted this review per the International Prospective Register of Systematic Reviews (PROSPERO) guidelines. This study performed a systematic literature review in February 2022 using the following electronic databases: Cochrane, MEDLINE, and EMBASE. Key terms include hand basal cell carcinoma, basal cell carcinoma, management, outcome, and recurrence. We evaluated articles according to predefined quality criteria.

Results

The study included 9725 patients and 51 published articles. A total of 35 case reports, 2 case series, 1 prospective study, and the remaining retrospective studies were evaluated. An asymptomatic skin lesion was the main complaint. In 10 studies, Moh surgery was the most frequently used treatment method. In the seven studies included in the meta-analysis, the overall incidence rate of recurrence among the included patients was 1.49 cases per year.

Conclusion

The optimal extent of surgical treatment is still controversial, though an early biopsy can help identify lesions at an early stage. It is the first study to provide occurrence rates based on a meta-analysis. Developing treatment guidelines for BCC of the hand will be the focus of future research.

Modulation of Hedgehog Signaling for the Treatment of Basal Cell Carcinoma and the Development of Preclinical Models

Basal Cell Carcinoma (BCC) is the most commonly diagnosed cancer worldwide. While the survivability of BCC is high, many patients are excluded from clinically available treatments due to health risks or personal choice. Further, patients with advanced or metastatic disease have severely limited treatment options. The dysregulation of the Hedgehog (Hh) signaling cascade drives onset and progression of BCC. As such, the modulation of this pathway has driven advancements in BCC research. In this review, we focus firstly on inhibitors that target the Hh pathway as chemotherapeutics against BCC. Two therapies targeting Hh signaling have been made clinically available for BCC patients, but these treatments suffer from limited initial efficacy and a high rate of chemoresistant tumor recurrence. Herein, we describe more recent developments of chemical scaffolds that have been designed to hopefully improve upon the available therapeutics. We secondly discuss the history and recent efforts involving modulation of the Hh genome as a method of producing in vivo models of BCC for preclinical research. While there are many advancements left to be made towards improving patient outcomes with BCC, it is clear that targeting the Hh pathway will remain at the forefront of research efforts in designing more effective chemotherapeutics as well as relevant preclinical models.

Vismodegib for Preservation of Visual Function in Patients with Advanced Periocular Basal Cell Carcinoma: The VISORB Trial

Background

Basal cell carcinoma (BCC) is a common skin cancer often curable by excision; however, for patients with BCC around the eye, excision places visual organs and function at risk. In this article, we test the hypothesis that use of the hedgehog inhibitor vismodegib will improve vision‐related outcomes in patients with orbital and extensive periocular BCC (opBCC).

Materials and Methods

In this open‐label, nonrandomized phase IV trial, we enrolled patients with globe‐ and lacrimal drainage system–threatening opBCC. To assess visual function in the context of invasive periorbital and lacrimal disease, we used a novel Visual Assessment Weighted Score (VAWS) in addition to standard ophthalmic exams. Primary endpoint was VAWS with a score of 21/50 (or greater) considered successful, signifying globe preservation. Tumor response was evaluated using RECIST v1.1. Surgical specimens were examined histologically by dermatopathologists.

Results

In 34 patients with opBCC, mean VAWS was 44/50 at baseline, 46/50 at 3 months, and 47/50 at 12 months or postsurgery. In total, 100% of patients maintained successful VAWS outcome at study endpoint. Compared with baseline, 3% (95% confidence interval [CI], 0.1–15.3) experienced major score decline (5+ points), 14.7% (95% CI, 5 to 31.1) experienced a minor decline (2–4 points), and 79.4% experienced a stable or improved score (95% CI, 62.1–91.3). A total of 56% (19) of patients demonstrated complete tumor regression by physical examination, and 47% (16) had complete regression by MRI/CT. A total of 79.4% (27) of patients underwent surgery, of which 67% (18) had no histologic evidence of disease, 22% (6) had residual disease with clear margins, and 11% (3) had residual disease extending to margins.

Conclusion

Vismodegib treatment, primary or neoadjuvant, preserves globe and visual function in patients with opBCC. Clinical trail identification number.NCT02436408.

Implications for Practice

Use of the antihedgehog inhibitor vismodegib resulted in preservation of end‐organ function, specifically with regard to preservation of the eye and lacrimal apparatus when treating extensive periocular basal cell carcinoma. Vismodegib as a neoadjuvant also maximized clinical benefit while minimizing toxic side effects. This is the first prospective clinical trial to demonstrate efficacy of neoadjuvant antihedgehog therapy for locally advanced periocular basal cell carcinoma, and the first such trial to demonstrate end‐organ preservation.

This article reports the results of a prospective clinical trial of vismodegib for patients with basal cell carcinoma occurring in the orbital and periocular regions to assess whether such treatment helps to preserve visual organs and function.

A Clinical Study of Basal Cell Carcinoma

INTRODUCTION

Basal cell carcinoma (BCC) is a non-melanocytic skin malignancy arising from basal cells of epidermis or follicular structures. Etiology of BCC is a multifactorial combination of genotype, phenotype, and environmental factors. There are several clinical variants of BCC including nodular, cystic, superficial, morphoeic, keratotic, pigmented and micronodular.

AIM

The aim of our study was to analyze the recent clinical trends of basal cell carcinoma by reviewing a single institution's experience.

METHODS

Total number of 422 patients clinically diagnosed with basal cell carcinoma were included in the study. Data on age, gender, skin type, personal and family history, duration of disease, localization of lesions, clinical type of lesions, and recurrence rate were collected and analyzed. The data were statistically evaluated.

RESULTS

More than 80% of all BCC's were located on sun-exposed skin areas (p<0.05).The male /female ratio was 1:0.92. The nodular BCC was the most frequent type (59.2%), followed by the superficial (16.1%), pigmented (15.2%) and morphoeic (9.5%) types. The nodular and pigmented types were predominant located on the head and neck, whereas the trunk was the most common location for the superficial type (p<0.05). The tumor is commonly found in concomitance with skin lesion related to chronic sun exposure, such as actinic keratoses, solar lentigines and facial telangiectasia. During this study period, 41 cases showed recurrence of the cancer as the overall recurrence rate was 9.7%. There were no cases with metastasis or fatal outcome.

CONCLUSIONS

The factors related to the development of BCC were older age and exposure to ultraviolet rays both in recreational and in occupational form. The prevention of BCC is based on the knowledge of risk factors, early diagnosis and treatment, particularly in susceptible populations.

Head and neck cutaneous basal cell carcinoma: what should the otorhinolaryngology head and neck surgeon care about?

Cutaneous basal cell carcinoma (cBCC) is the most common malignancy diagnosed in the human population. cBCC presents an increasing incidence which, in the near future, will be higher than all other cancers combined. The majority of cBCC are located in the head and the neck. A diversity of management modalities is currently available; nonetheless, surgical excision remains the main modality of treatment. cBCC rarely metastasises and presents a low mortality rate. cBCC morbidity is influenced by local invasion and destruction, especially in the face, where function and aesthetics are major issues. Easy accessibility to the face and skin on the neck makes cBCC an important issue for otorhinolaryngology head and neck surgeons who must be aware and committed in its management, as the main modality of treatment continues to be surgical. The aim of this review is to present a brief and practical overview of head and neck cBCC management for ear, nose and throat (ENT) surgeons, discussing key issues about its epidemiology, risk factors, diagnosis and pathogenesis.

Molecular basis of basal cell carcinoma

Basal cell carcinoma is the most common cancer, presenting low mortality but high morbidity, and it has as risk factor exposure to sunlight, especially UVB spectrum. The most important constitutional risk factors for basal cell carcinoma development are clear phototypes (I and II, Fitzpatrick classification), family history of basal cell carcinoma (30-60%), freckles in childhood, eyes and light hair. The environmental risk factor better established is exposure to ultraviolet radiation. However, different solar exposure scenarios probably are independent risk factors for certain clinical and histological types, topographies and prognosis of this tumor, and focus of controversy among researchers. Studies confirm that changes in cellular genes Hedgehog signaling pathway are associated with the development of basal cell carcinoma. The cellular Hedgehog signaling pathway is activated in organogenesis, but is altered in various types of tumors.

Basal cell carcinoma, squamous cell carcinoma and melanoma of the head and face

Ultraviolet light (UV) is an important risk factor for cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma and cutaneous melanoma of the skin. These cancers most commonly affect persons with fair skin and blue eyes who sunburn rather than suntan. However, each of these cancers appears to be associated with a different pattern of UV exposure and to be mediated by different intracellular molecular pathways.

Some melanocortin 1 receptor (MC1R) gene variants play a direct role in the pathogenesis of cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma and cutaneous melanoma apart from their role in determining a cancer-prone pigmentory phenotype (fair skin, red hair, blue eyes) through their interactions with other genes regulating immuno-inflammatory responses, DNA repair or apoptosis.

In this short review we focus on the aetiological role of UV in cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma and cutaneous melanoma of the skin, and on some associated biopathological events.

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.

Evidence that Gsta4 modifies susceptibility to skin tumor development in mice and humans

BACKGROUND

The incidence of nonmelanoma skin cancer (NMSC) is equivalent to that of all other cancers combined. Previously, we mapped the 12-O-tetradecanoylphorbol-13-acetate (TPA) skin tumor promotion susceptibility locus, Psl1, to distal chromosome 9 in crosses of sensitive DBA/2 mice with relatively resistant C57BL/6 mice. Here, we used the mouse two-stage skin carcinogenesis model to identify the gene(s) responsible for the effects of Psl1.

METHODS

Interval-specific congenic mouse strains (n ≥ 59 mice per strain) were used to more precisely map the Psl1 locus. Having identified glutathione S-transferase α4 (Gsta4) as a candidate tumor promotion susceptibility gene that mapped within the delimited region, we analyzed Gsta4-deficient mice (n = 62) for susceptibility to skin tumor promotion by TPA. We used quantitative polymerase chain reaction, western blotting, and immunohistochemistry to verify induction of Gsta4 in mouse epidermis following TPA treatment and biochemical assays to associate Gsta4 activity with tumor promotion susceptibility. In addition, single-nucleotide polymorphisms (SNPs) in GSTA4 were analyzed in a case-control study of 414 NMSC patients and 450 control subjects to examine their association with human NMSC. Statistical analyses of tumor studies in mice were one-sided, whereas all other statistical analyses were two-sided.

RESULTS

Analyses of congenic mice indicated that at least two loci, Psl1.1 and Psl1.2, map to distal chromosome 9 and confer susceptibility to skin tumor promotion by TPA. Gsta4 maps to Psl1.2 and was highly induced (mRNA and protein) in the epidermis of resistant C57BL/6 mice compared with that of sensitive DBA/2 mice following treatment with TPA. Gsta4 activity levels were also higher in the epidermis of C57BL/6 mice following treatment with TPA. Gsta4-deficient mice (C57BL/6.Gsta4(-/-) mice) were more sensitive to TPA skin tumor promotion (0.8 tumors per mouse vs 0.4 tumors per mouse in wild-type controls; difference = 0.4 tumors per mouse; 95% confidence interval = 0.1 to 0.7, P = .007). Furthermore, inheritance of polymorphisms in GSTA4 was associated with risk of human NMSC. Three SNPs were found to be independent predictors of NMSC risk. Two of these were associated with increased risk of NMSC (odds ratios [ORs] = 1.60 to 3.42), while the third was associated with decreased risk of NMSC (OR = 0.63). In addition, a fourth SNP was associated with decreased risk of basal cell carcinoma only (OR = 0.44).

CONCLUSIONS

Gsta4/GSTA4 is a novel susceptibility gene for NMSC that affects risk in both mice and humans.

UV fingerprints predominate in the PTCH mutation spectra of basal cell carcinomas independent of clinical phenotype

Basal cell carcinoma (BCC) shows a wide interpatient variation in lesion accrual. To determine whether certain tumorigenic fingerprints and potentially predisposing patched (PTCH) tumor suppressor single-nucleotide polymorphisms (SNPs) are distributed differently among sporadic BCC patients, we compared the PTCH mutation spectra in early-onset BCC (first lesion at age < 35 years), regular BCC (first lesion at age > or = 35 years and < 10 lesions), and multiple BCC (> or = 10 lesions). The PTCH gene was mutated in 29 of 60 cases (48%). Most of the PTCH mutations bore the UV fingerprint (i.e., C --> T or tandem CC --> TT transitions at dipyrimidine sites). However, neither the proportion nor the spectra of exonic PTCH mutations differed significantly among the three groups. A large number of SNPs (IVS10+99C/T, IVS11-51G/C, 1665T/C, 1686C/T, IVS15+9G/C, IVS16-80G/C, IVS17+21G/A, and 3944C/T or its combinations) were also detected, but again their incidence did not differ significantly among the groups. Interestingly, expression of the IVS16-80G/C and the IVS17+21G/A genotype did not achieve the Hardy-Weinberg equilibrium in patients with regular and/or early-onset BCC. These data suggest that a (UV-) mutated PTCH gene is important for sporadic BCC formation independent of clinical phenotype and that the IVS16-80G/C and/or IVS17+21G/A SNP site might be important for tumorigenesis in certain BCC patients.

Impact of some constitutional characteristics on the development of basal cell carcinoma

Background/Aim. Basal cell carcinoma (BCC) is the most common form of skin cancer in the white population. Increasing incidence of BCC imposes the requirement to identify the risk factors due to eventual preventive action. The aim of this study was to assess the role of some constitutional characteristics in development of BCC among the Montenegrin population. Methods. A case-control study was conducted at the Dermatology Department of Clinical Center of Montenegro in Podgorica from 2002?2003. The study group included 100 histopatologically confirmed BCC cases, while the control group consisted of 100 patients from the same department, who did not present skin cancer and who were individually matched to the cases by sex and age (?5 years). All participants were interviewed using an epidemiological questionnaire. For statistical analysis t test and McNemar ?2 test for matched pairs and multivariate logistic regression analyses were used. Results. The risk for development of BCC was increased among the persons with lighter hair color (t = 4.63; df = 99; p < 0.001), fair skin (t = 2.37; df = 99; p = 0.020), lighter eyes color (t = 2.86; df = 99; p = 0.005), with nevuses (OR = 13.13; p = 0.025; 95% IP = 1.39-12.03), and among those whose skin tone after sun exposure remained light (OR = 3.14; p = 0.001; 95%IP = 1.59-6.18). Conclusion. Our study confirmed the significance of constitutional characteristics such as lighter hair color, fair skin, lighter eyes color, and the presence of nevuses in the development of BCC. .

[Exposure to sun radiation as a risk factor for the occurrence of basal cell carcinoma in the Montenegrian population]

BACKGROUND/AIM

[corrected] Basal cell carcinoma (BCC) is the most frequent form of carcinomas in the whites. Among the environmental factors, the most important risk factor for its occurrence is the expasure to sun radiation. The aim of this study was to assess the role of the sun radiation in the development of basal cell carcinoma BCC in the Montenegrian population.

METHODS

A case-control study was conducted in a period from 2002-2003. The study group included 100 histopatologically confirmed cases with BCC, while the control group included 100 patients from the same population, who did not present skin cancer and who were individually matched with the cases from the study group by sex and age (+/- 5 years). All the participants were interviewed using an epidemiological questionnaire. For statistical analysis, the chi-squared test and univariate logistic regression analysis were used.

RESULTS

The risk for development of BCC was increased in the persons: that always had burns with no tan during the exposure to sunlight (OR = 1.75; 95% CI = 1.20-2.55; p = 0.003); that developed sunburns after two hours of the exposure to sunlight (OR = 3.72; 95% CI = 2.39-5.79; p < 0.001) that kept light tan or remained without changes in childhood and adolescence after the repeated exposures to sunlight (OR = 2.92; 95% CI = 1.89-4.52; p < 0.001) that often had severe and painful sunburns (OR = 4.48; 95% CI = 2.74-7.33; p < 0.001).

CONCLUSION

Our study confirmed the significance of sunlight exposure for the development of BCC.

Polymorphism in the nuclear excision repair gene ERCC2/XPD: association between an exon 6-exon 10 haplotype and susceptibility to cutaneous basal cell carcinoma

Cutaneous basal cell carcinoma (BCC) risk is mediated by interactions between ultraviolet radiation (UVR) and host factors, including DNA repair efficiency. We investigated the association between BCC risk and SNPs in exon 6 (c.466C > A, dbSNP238406:g.C > A; designated C/A156), exon 10 (c.932G > A, dbSNP1799793:g.G > A; designated G/A312), and exon 23 (c.2251A > C, dbSNP13181:g.A > C; designated A/C751) of the nucleotide excision repair gene, XPD (ERCC2; excision repair cross-complementing repair deficiency, complementation 2 [xeroderma pigmentosum D]). XPD genotype frequencies were not significantly different in 509 cases and 379 controls, although AA156 (odds ratio [OR]=0.61, 95% confidence interval [CI]=0.37-1.01, P=0.052) and AA312 (OR=0.65, 95% CI=0.40-1.05, P=0.08) were linked with reduced risk. A156-A312 and A156-A312-A751 haplotype frequencies however, were significantly lower in cases than controls (OR=0.12, 95% CI=0.05-0.31, P < 0.001; OR=0.10, 95% CI=0.03-0.33, P < 0.001). We confirmed the robustness of these findings by showing significant associations of the haplotypes with risk in two randomly selected equal sized groups of cases and controls and, using the false positive report probability (FPRP) approach (FPRP values < 0.001 and < 0.004, respectively). A156-A312 was similarly associated with reduced risk in subgroups, including cases with no family history of skin cancer, with only BCC on the head/neck, and those with a high rate of increase in BCC numbers. The association was not dependent on gender, age, or extent of UVR exposure. A156-A312 was found in 6.3% of controls and the corresponding risk haplotype, C156-G312 (OR=1.65, 95% CI=1.21-2.26, P=0.002) in 35.4% of controls. We interpret these data as showing that XPD SNP mediate susceptibility to BCC.

Current modalities and new advances in the treatment of basal cell carcinoma

Basal cell carcinoma (BCC) is one of the most common cancers. Surgical extirpation is currently the standard of care for BCC, which is associated with several advantages and disadvantages. Procedures such as surgical excision used to treat superficial BCC (sBCC) and nodular BCC (nBCC) may have high 5-year recurrence rates if tumors are not completely excised. Curettage with electrodesiccation is a common method for treating primary BCC. However, multiple cycles are recommended and the procedure can have unsatisfactory cosmetic results (e.g. scarring and hypopigmentation). Mohs micrographic surgery has a low rate of disease recurrence but is a specialized procedure usually limited to specific indications (e.g. high-risk tumors). Cryosurgery and photodynamic therapy require multiple cycles and are associated with variable cosmetic outcomes and recurrence rates. As with any procedure, potential risks and patient quality-of-life issues need to be considered. In addition, substantial patient and healthcare provider inconvenience limit the practical utility of some modalities. Pharmacologic interventions provide another treatment option as adjunctive or monotherapy. Investigations of imiquimod, a novel immune response modifier, have indicated that this topical, noninvasive agent is safe and well tolerated and may be efficacious in the treatment of BCC. This review will highlight the role of standard treatment modalities and introduce new advances in the treatment of BCC.

A common tumor, an uncommon location: basal cell carcinoma of the nipple and areola in a 49-year-old woman

BACKGROUND

Basal cell carcinoma (BCC) occurring on sun-protected regions is an uncommon phenomenon. BCC of the nipple is an exceedingly rare event.

METHOD

We review the literature on BCC of the female nipple and herein describe the eighth reported case in the English literature. Our patient was treated with Mohs micrographic surgery and sentinel lymph node biopsy.

CONCLUSION

BCC of the nipple are extremely rare tumors with unclear etiology. They can be aggressive and are capable of causing significant morbidity and mortality if they are neglected or improperly treated. With continued reporting of the diagnosis, treatment, and follow-up of these patients, we may gain an understanding of the pathogenesis, as well as the best method of control for these unusual tumors.

Susceptibility to basal cell carcinoma: associations with PTCH polymorphisms

Loss of function of the human patched gene (PTCH) is common and critical in basal cell carcinoma (BCC) development. Indirect evidence suggests polymorphism in PTCH mediates BCC risk. We studied 659 BCC cases and 300 controls to determine if exon 2(318), 3(429), 11(1552), 12(1665), 12(1686), 14(2199) and 23(3944) and intron 9(1336-135) and 15(2560+9)PTCH variants were sufficiently common for use in case-control studies, and if selected markers were associated with risk. Intron 15(2560+9) and exon 23(3944) variants were studied further. Their genotype frequencies were not significantly different in controls and cases, though frequency of the G(2560+9)-C(3944) haplotype was lower in all cases (odds ratio=0.44, p=0.009) and those stratified by BCC site and rate of development of further tumours. This association was not mediated by the extent of UVR exposure. We confirmed the robustness of these findings by showing these associations demonstrated similar odds ratios in two groups of randomly selected cases and controls, and using the false positive report probability (FPRP) approach described by Wacholder et al. (2004). The FPRP value (0.168) was in the noteworthy category. These data, showing for the first time that PTCH polymorphism mediates susceptibility, are compatible with reports showing that PTCH haploinsufficiency influences development of BCC precursor lesions.

Effect of polymorphisms in XPD, RAI, ASE-1 and ERCC1 on the risk of basal cell carcinoma among Caucasians after age 50

We have investigated the occurrence of basal cell carcinoma (BCC) in relation to a number of single nucleotide polymorphisms (SNPs) in the chromosomal region 19q13.2-3. A case-control study including 322 basal cell carcinoma cases and a similar number of controls was nested in a population-based prospective investigation encompassing 57,053 Danes (aged 50-64 at inclusion) living in Copenhagen or Aarhus in Denmark. We found that the polymorphism XPD Arg156Arg was associated with risk of basal cell carcinoma (rate ratio (RR)=1.59, 95% confidence interval (CI)=1.02-2.50 for homozygous carriers of the A-allele), and that the association was strongest in the youngest age interval of the study group (50-55 years) (RR=2.33, 95% CI=1.03-5.28). The polymorphisms XPD Asp312Asn and XPD Lys751Gln were not associated with risk of basal cell carcinoma. While it cannot be ruled out that the present findings are due to chance, the present results are consistent with previous findings that XPD Arg156Arg is a weak risk factor for basal cell carcinoma.

PTCH polymorphism is associated with the rate of increase in basal cell carcinoma numbers during follow-up: preliminary data on the influence of an exon 12-exon 23 haplotype

After first presentation with a basal cell carcinoma (BCC), patients demonstrate interindividual diversity in the rate of development of further BCCs (number/year of follow-up). The mechanism for this variation is unknown. In this study, we evaluated whether PTCH variants mediate this phenomenon. We used negative binomial regression analysis to identify associations between BCC numbers/year and host characteristics, parameters of exposure to ultraviolet radiation (UVR), and PTCH exon 12(1686) C/T, intron 15(2560+9) G/C, and exon 23(3944) C/T genotypes and haplotypes in 279 BCC cases who presented with an initial tumor on the head/neck. PTCH genotypes were not significantly associated with BCCs/year, although cases with two copies of the C1686-C3944 haplotype developed significantly fewer BCCs/year than those without this haplotype (rate ratio = 0.44; 95% CI = 0.27-0.71). Cases with one copy of T1686-T3944 developed more BCCs/year (rate ratio = 2.46; 95% CI = 1.27-3.97) than those without the haplotype. We found no significant associations between BCCs/year and the other PTCH haplotypes studied. We reexamined the association of C1686-C3944 with BCCs/year in a model that included UVR exposure parameters (sunburning in childhood, sunbathing score, intermittency of exposure between 40 and 60 years of age, exposure in hours/year) and skin type, gender, and age at first presentation. The association between C1686-C3944 and BCCs/year remained significant (rate ratio = 0.44; 95% CI = 0.26-0.73 for two copies of the haplotype). The data show that allelic variation in PTCH contributes to the rate of development of BCC.