Predicting the Risk of a Second Basal Cell Carcinoma

Comparison of Socio-demographic Characteristics, Tumour Features, and Surgical Treatment Outcomes in Phenotypic Variants of Basal Cell Carcinoma

Background

Basal cell carcinoma (BCC) cases exhibit variations in tumour number, location, and growth patterns. While some patients develop only one BCC, approximately one-third of patients later develop one or more additional lesions.

Aims

The aim of the study was to identify risk factors for further BCC lesions in patients with different phenotypic presentations.

Materials and Methods

We retrospectively evaluated 1052 histopathologically diagnosed tumours of 861 patients, who were divided into four phenotypic presentation groups according to tumour number at initial diagnosis and during follow-up. Age, sex, tumour characteristics, surgical margins, re-excision and residual tumour rates were compared. Univariate and multivariate logistic regression analyses were performed to determine risk factors for multiple tumour development.

Results

There were 723 patients in the single presentation phenotype 1 (SPP1) group, 19 in the SPP-more group, 114 in the multiple presentation phenotype (MPP)-cluster initial group, and five patients in the MPP-cluster later group. Male sex was more common in the MPP-cluster later group (P = 0.028). The mean age was lower in the SPP1 and SPP-more groups (P = 0.002). Ear involvement was more common in the MPP-cluster later group (P < 0.05). Superficial and basosquamous subtypes were more common in the SPP-more and MPP-cluster later groups (P < 0.05). Re-excision and residual tumour rates were lowest in the SPP1 group (P < 0.05). Age over 69 years, male sex, and periorbital or upper extremity location were significant risk factors for multiple tumour development (P < 0.05).

Limitations

The limitations of our study include the inability to evaluate environmental risk factors, phenotypic and ethnic characteristics, and the short follow-up period for newly added patients.

Conclusions

Predicting different phenotypic presentations by taking the age, gender, and tumour characteristics (localization, histopathological subtype) of the patients into account may allow new tumours to be detected at an early stage.

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.

Basal cell carcinomas of the scalp after radiotherapy for tinea capitis: Clinicopathological study in a case series of 96 patients with analysis of 427 tumours

BACKGROUND/OBJECTIVES

Low-dose X-ray radiotherapy to treat tinea capitis during childhood is a well-known risk factor for scalp basal cell carcinomas (BCCs). Post-radiotherapy BCCs are often multiple, and it has been suggested that they display more aggressive features. Our main objective was to study the clinicopathological aspects of post-radiotherapy BCCs to evaluate their biological behaviour and identify features that may differ from other BCCs.

METHODS

We performed an observational, retrospective study assessing multiple clinical and pathological characteristics of patients with post-radiotherapy BCCs.

RESULTS

We studied 96 patients with 427 post-radiotherapy scalp BCCs. Post-radiotherapy BCCs were often multiple (median of 4 lesions/patient, ranging from 1 to 54). Significant comorbidities included a high incidence of thyroid disease and meningiomas. Recurrences were observed in 23% of patients, but there may be confounding factors, such as referral bias, heterogenous treatment modalities and occurrence of new tumours due to field effect. We found a high incidence of infundibulocystic BCCs (in 14.6% of patients and corresponding to 5.4% of the total number of tumours), trichoblastomas (5.2%) and neurofibromas of the scalp (10%).

CONCLUSIONS

This study is consistent with the occurrence of multiple lesions (sometimes numerous) and a relatively high tendency for recurrence in post-radiotherapy BCCs, as suggested by previous studies. We also found a high incidence of the infundibulocystic variant and a higher risk of follicular tumours and neurofibromas, which suggests that radiotherapy may influence the type of differentiation of BCCs and contribute to induce neoplasms of different cell lines.

Clinical and pathological features associated with high-risk, multiple, and recurrent basal cell carcinomas: a retrospective cohort analysis from the Levantine coast of the Mediterranean Sea

Basal cell carcinoma (BCC) data coming from the Levantine coast of the Mediterranean Sea are limited. The study aimed to primarily analyze the demographic, clinical, pathological, and prognostic characteristics of BCC in this region of the world and secondarily identify features associated with high-risk, recurrent, or multiple BCCs. Patients with at least one diagnosis of BCC registered in the pathology department between January 2015 and December 2019 were included in this analytical retrospective single-center cohort study. Patients with basal cell nevus syndrome were excluded. Patients' characteristics and pathological features were collected through file check for a first analysis. Risk factors and evolution were sought through a phone call interview for the second analysis. The first analysis included 506 BCCs corresponding to 365 patients with a mean age of 65 ± 15 years, twenty-two (6%) were less than 40 years old, 180 (49.3%) were women, and 85 (23.3%) had two or more BCCs. The second analysis included 279 BCCs corresponding to 205 patients. Periorificial and infiltrative BCCs were more frequent in men. Periorificial tumors were more frequently nodular or infiltrative and were associated with recurrence. Tumors with perineural involvement were histologically never nodular nor superficial. Recurrence was more frequent in BCCs having periorificial location, a size larger than 2 cm, or an infiltrative subtype. Multiple BCCs were more frequent in patients with light skin type or familial history of skin cancer. High-risk BCCs were more common in patients with low sun exposure.

Multiple Basal Cell Carcinomas in Immunocompetent Patients

Simple Summary

It is widely known that long-term treatment with immunosuppressive drugs represents a risk factor for the onset of malignancies, including multiple basal cell carcinomas. However, multiple basal carcinomas are ao found in the general population, and even in the absence of specific predisposing genetic mutations. This paper aims, through the retrospective evaluation of all patients diagnosed and surgically treated for basal cell carcinomas during 5 years at our Dermatological Division, to identify the characteristics of these subjects and any possible risk factors, useful for outlining specific surveillance programs. In our experience, multiple carcinomas were identified in over 24% of the subjects analyzed, with several lesions removed, ranging from 2 to 11, confirming the relevance of this phenomenon.

Abstract

Background: The onset of multiple BCCs is a relatively common condition, not only among patients undergoing chronic treatment with immunosuppressant drugs, but also in the general population, although specific risk factors for immunocompetent patients have not been identified. A putative role of somatic mutations in the hedgehog pathway should be considered. Methods: This study is a retrospective observation of all patients diagnosed and surgically treated for BCCs during 5 years at our Dermatological Division. For these patients, we evaluated clinical and histopathological characteristics and data about possible risk factors for BCC. Results: Five-hundred and six patients affected by multiple BCCs, accounting for the 24.2% of the entire sample, have been identified. In these patients, the total number of BCCs was 1516, ranging from 2 to 11. Subjects affected by multiple BCCs were more frequently males, with an older age at diagnosis; multiple BCCs developed mainly on the trunk and were often represented by a nodular histotype. The multivariate analysis highlighted that male gender, older age, nodular BCC, or face involvement at the first diagnosis are risk factors for the development of multiple BCCs. Conclusions: The frequency of multiple BCCs even among the non-immunocompromised population underlines the need to subject patients to a close surveillance program, to allow early diagnosis and treatment of additional cancers.

Does the histopathological subtype of primary basal cell carcinoma predict the subtype of secondary tumours? What role do genetic mutations play?

Background

Basal cell carcinoma (BCC) is one of the most common malignancies in the world. The frequency of histopathological subtypes and the distribution on the body of BCC has been well documented. Less has been written on the nature of secondary tumours. The genetics of BCC is starting to be understood, particularly with the advent of newer medical treatments (hedgehog inhibitors).

Objectives

To determine if primary basal cell carcinoma histopathological subtype predicts secondary tumour subtype, as well as their anatomical distribution.

Methods

A retrospective case series of patients over the age of 18 was performed from 2009 to 2014, with at least two separate diagnoses of BCC.

Results

In 394 identified patients, a total of 1355 BCCs arose in the cohort over the 6-year study period. The number of secondary BCCs per patient ranged from 2 to 19 tumours. Nodular BCC was the most likely to reoccur in secondary tumours (53.3%), followed by mixed subtypes (45.7%).

Conclusions

Within our study, we did find a predisposition for secondary BCCs to be of the same histopathological subtype as the primary, particularly with respect to nodular and mixed tumours. Furthermore, we found that secondary tumours were also more likely to occur on the same anatomical site as the primary tumour. We are only just beginning to under the genetic mutations involved in subtype formation.

Novel Insights for Patients with Multiple Basal Cell Carcinomas and Tumors at High-Risk for Recurrence: Risk Factors, Clinical Morphology, and Dermatoscopy

INTRODUCTION

Basal cell carcinoma (BCC) quite frequently presents as multiple tumors in individual patients. Neoplasm's risk factors for local recurrence have a critical impact on therapeutic management.

OBJECTIVE

To detect risk factors for multiple BCCs (mBCC) in individual patients and to describe clinical and dermatoscopic features of low- and high-risk tumors.

MATERIALS & METHODS

Our study included 225 patients with 304 surgically excised primary BCCs. All patients' medical history and demographics were recorded. Clinical and dermatoscopic images of BCCs were evaluated for predefined criteria and statistical analyses were performed.

RESULTS

Grade II-III sunburns before adulthood (OR 2.146, p = 0.031) and a personal history of BCC (OR 3.403, p < 0.001) were the major predisposing factors for mBCC. Clinically obvious white color (OR 3.168, p < 0.001) and dermatoscopic detection of white shiny lines (OR 2.085, p = 0.025) represented strongly prognostic variables of high-risk BCC. Similarly, extensive clinico-dermatoscopic ulceration (up to 9.2-fold) and nodular morphology (3.6-fold) raise the possibility for high-risk BCC. On the contrary, dermatoscopic evidence of blue-black coloration had a negative prognostic value for high-risk neoplasms (light OR 0.269, p < 0.001/partial OR 0.198, p = 0.001).

CONCLUSIONS

Profiling of mBCC patients and a thorough knowledge of high-risk tumors' clinico-dermatoscopic morphology could provide physicians with important information towards prevention of this neoplasm.

Development of Multiple-Lesion Basal Cell Carcinoma of the Skin: A Comprehensive Review

An interesting clinical feature of basal cell carcinoma (BCC) of the skin is a marked variation in tumor number, sites, and accrual. Some individuals develop only a single BCC lesion with no impact on health status, while a significant proportion is affected repeatedly with new primary tumors at various body sites. Approximately 29% of patients with a first BCC will develop at least 1 more lesion during their lifetime. The candidate predictors for multiple BCC development include younger age and a superficial BCC subtype at the time of the first diagnosis, red hair phenotype, initial or frequent tumor location on the trunk or on the upper limbs, and male gender. The pathogenesis of multiple BCC development does not seem to be related to greater UVR exposure. Individual genetic susceptibility may have a greater impact than extrinsic factors. In clinical practice, it is meaningful to estimate the probability of new BCC development in patients who have an initial lesion. A reliable prediction model for individualized risk stratification remains a subject of continued research; however, a focus on the risk factor profile is beneficial for clinical screening and may help clinicians to determine the individuals who should be followed up more closely.

Diagnosis and Treatment of Basal Cell Carcinoma in Specialized Dermatology Units: A Clinical Practice Guideline

BACKGROUND AND OBJECTIVE

Basal cell carcinoma (BCC) is the most common skin cancer in the general population. BCC is managed in a variety of ways, and available international guidelines are difficult to put into practice in Spain. This guideline aims to improve the management of BCC based on current evidence and provide a point of reference for Spanish dermatologists.

MATERIAL AND METHODS

Members of the Spanish Oncologic Dermatology and Surgery Group (GEDOC) with experience treating BCC were invited to participate in drafting this guideline. The drafters used the ADAPTE collaboration process to develop the new guideline based on existing ones, first summarizing the care pathway and posing relevant clinical questions. They then searched for guidelines, assessed them with the AGREEII (Appraisal of Guidelines for Research and Evaluation) tool, and searched the selected guidelines for answers to the clinical questions. Finally, the recommendations were drafted and submitted for external review.

RESULTS

The highest-scoring guidelines were from the Association of Dermatologists, the National Comprehensive Cancer Network, the European Dermatology Forum, and the European Academy of Dermatology and Venereology. A total of 11 clinical questions were answered.

CONCLUSIONS

This new guideline answers the working group's clinical questions about the routine management of BCC in Spain. It provides dermatologists with a tool they can use for decision-making while taking into consideration the resources available and patient preferences.

Predicting keratinocyte carcinoma in patients with actinic keratosis: development and internal validation of a multivariable risk-prediction model

BACKGROUND

Patients with actinic keratosis (AK) are at increased risk for developing keratinocyte carcinoma (KC) but predictive factors and their risk rates are unknown.

OBJECTIVES

To develop and internally validate a prediction model to calculate the absolute risk of a first KC in patients with AK.

METHODS

The risk-prediction model was based on the prospective population-based Rotterdam Study cohort. We hereto analysed the data of participants with at least one AK lesion at cohort baseline using a multivariable Cox proportional hazards model and included 13 a priori defined candidate predictor variables considering phenotypic, genetic and lifestyle risk factors. KCs were identified by linkage of the data with the Dutch Pathology Registry.

RESULTS

Of the 1169 AK participants at baseline, 176 (15·1%) developed a KC after a median follow-up of 1·8 years. The final model with significant predictors was obtained after backward stepwise selection and comprised the presence of four to nine AKs [hazard ratio (HR) 1·68, 95% confidence interval (CI) 1·17-2·42], 10 or more AKs (HR 2·44, 95% CI 1·65-3·61), AK localization on the upper extremities (HR 0·75, 95% CI 0·52-1·08) or elsewhere except the head (HR 1·40, 95% CI 0·98-2·01) and coffee consumption (HR 0·92, 95% CI 0·84-1·01). Evaluation of the discriminative ability of the model showed a bootstrap validated concordance index (c-index) of 0·60.

CONCLUSIONS

We showed that the risk of KC in patients with AK can be calculated with the use of four easily assessable predictor variables. Given the c-index, extension of the model with additional, currently unknown predictor variables is desirable. Linked Comment: Kim et al. Br J Dermatol 2020; 183:415-416.

Healthcare utilization and management of actinic keratosis in primary and secondary care: a complementary database analysis

Background

The high prevalence of actinic keratosis (AK) requires the optimal use of healthcare resources.

Objectives

To gain insight in to the healthcare utilization of people with AK in a population‐based cohort, and the management of AK in a primary and secondary care setting.

Methods

A retrospective cohort study using three complementary data sources was conducted to describe the use of care, diagnosis, treatment and follow‐up of patients with AK in the Netherlands. Data sources consisted of a population‐based cohort study (Rotterdam Study), routine general practitioner (GP) records (Integrated Primary Care Information) and nationwide claims data (DRG Information System).

Results

In the population‐based cohort (Rotterdam Study), 69% (918 of 1322) of participants diagnosed with AK during a skin‐screening visit had no previous AK‐related visit in their GP record. This proportion was 50% for participants with extensive AK (i.e. ≥ 10 AKs; n = 270). Cryotherapy was the most used AK treatment by both GPs (78%) and dermatologists (41–56%). Topical agents were the second most used treatment by dermatologists (13–21%) but were rarely applied in primary care (2%). During the first AK‐related GP visit, 31% (171 of 554) were referred to a dermatologist, and the likelihood of being referred was comparable between low‐ and high‐risk patients, which is inconsistent with the Dutch general practitioner guidelines for ‘suspicious skin lesions’ from 2017. Annually, 40 000 new claims representing 13% of all dermatology claims were labelled as cutaneous premalignancy. Extensive follow‐up rates (56%) in secondary care were registered, while only 18% received a claim for a subsequent cutaneous malignancy in 5 years.

Conclusions

AK management seems to diverge from guidelines in both primary and secondary care. Underutilization of field treatments, inappropriate treatments and high referral rates without proper risk stratification in primary care, combined with extensive follow‐up in secondary care result in the inefficient use of healthcare resources and overburdening in secondary care. Efforts directed to better risk differentiation and guideline adherence may prove useful in increasing the efficiency in AK management.

What's already known about this topic?

The prevalence of actinic keratosis (AK) is high and, in particular, multiple AKs are a strong skin cancer predictor.

The high prevalence of AK requires optimal use of healthcare resources.

Nevertheless, (population based) AK healthcare utilization and management data are very rare.

What does this study add?

Although AK‐related care already consumes substantial resources, about 70% of the AK population has never received care.

Primary care AK management demonstrated underutilization of topical therapies and high referral rates without proper risk stratification, while in secondary care the extensive follow‐up schedules were applied.

This inefficient use of healthcare resources highlights the need for better harmonization and risk stratification to increase the efficiency of AK care.

Linked Comment: https://doi.org/10.1111/bjd.17862.

https://doi.org/10.1111/bjd.18269 available online

https://www.bjdonline.com/article/

Non-genetic and genetic predictors of a superficial first basal cell carcinoma

Background

Several observational studies have suggested differences in the risk factor profile between patients with superficial basal cell carcinomas (BCCs) and non‐superficial BCCs.

Objective

To test the reproducibility of previous study findings and to find new genetic and non‐genetic predictors for patients with a superficial first BCC.

Methods

A total of 14.628 participants of northwestern European descent aged 45 years or older from a prospective population‐based cohort study (Rotterdam Study) were linked with the Dutch Pathology Registry (PALGA) of whom 1528 were identified as BCC patients. After exclusion, 948 eligible BCC patients remained for further non‐genetic analyses and 1014 for genetic analyses. We included 11 phenotypic, environmental and tumour‐specific characteristics, and 20 candidate single nucleotide polymorphisms (SNP) as potential predictors for patients with a superficial first BCC. We performed binary logistic multivariable regression analyses.

Results

We found that patients with a superficial first BCC were significantly younger, almost two times more often female and 12–18 times more likely to have their BCC on the trunk or extremities than patients with a non‐superficial first BCC. One SNP (rs12203592), mapped to IRF4, looked promising (OR 1.83, 95% CI 1.13–2.97, P‐value <0.05), but after adjustment for multiple testing, no significant differences in genetic make‐up between superficial BCC and non‐superficial BCC patients were found.

Conclusion

We conclude that patients with a superficial BCC differ from non‐superficial BCC patients with respect to environmental factors (tumour localization as a proxy for UVR exposure) and phenotypic characteristics (age and sex), but we found no difference in genotype. As superficial BCC patients develop their first BCCs at a younger age, they could be at higher lifetime risk for subsequent skin cancers and therefore be an important group for secondary prevention.

Linked article: This article is commented on G. Argenziano et. al., p. 461 in this issue. To view this article visit https://doi.org/10.1111/jdv.15486.

Histopathological and patient-related characteristics of basal cell carcinomas of the head and neck influencing therapeutic management

The authors hypothesize that histopathological characteristics of basal cell carcinomas of the head and neck (BCCHN) have changed over time and the correlation of BCCHN localization and histological tumour type can help improving the number and quality of necessary therapeutic interventions. Information of 222 patients with 344 BCCHN was gained. Descriptive measures were compared to prior studies to prove whether or not characteristics of basal cell carcinomas or patients have changed over time. Afterwards descriptive measures were correlated with number of conducted operations to evaluate if tumour localization, histological tumour type and number of operations depend on one another. Aggravating factors which lead to a higher number of operations were older age, greater size of BCCHN, adjacent elastosis, the localizations eye, ear and nose and histological tumour types morpheaform and nodularulcerated. In comparison to earlier studies characteristics of BCCHN and patients showed positive developments because of grown awareness of BCCHN. Furthermore, our correlations demonstrate that therapeutic results of BCCHN treatment are continuously improving. Nevertheless, treatment of aggressive morpheaform BCCHN in combination with distinctive patient characteristics still needs improvement.

Genotypic and Phenotypic Features of BAP1 Cancer Syndrome: A Report of 8 New Families and Review of Cases in the Literature

Importance

Patients with germline mutations in BAP1 may develop several flesh-colored melanocytic BAP1-mutated atypical intradermal tumors (MBAITs). These tumors generally develop earlier than other BAP1-associated tumors, highlighting an important role for dermatologists in identifying and screening patients with a history suggestive of a germline mutation.

Objective

To describe 8 new families with germline mutations in BAP1 and provide a comprehensive review of reported cases.

Design, Settings and Participants

Patients were identified in an outpatient dermatology clinical setting over a 6-month period (10 mutation carriers from 8 families) and through a literature review using PubMed (205 patients).

Exposures

Mutations were identified through next-generation sequencing of saliva or blood samples, and RNA was extracted from fibroblasts cultured from a patient with an intronic variant to determine the impact of the mutation on the coding sequence.

Main Outcomes and Measures

All 215 patients were assessed for personal and/or family history and genotype. These findings were compiled and assessed for any association between genotype and phenotype.

Results

Overall, this study included 215 patients (108 women, 91 men, and 16 gender unspecified; median [range] age, 46.5 [10.0-79.0] years). Nine of the 10 patients who were identified in the outpatient dermatology setting were found to have MBAITs on clinical examination. Forty of 53 patients (75%) identified in the literature review who underwent total-body skin examinations (TBSE) were found to have MBAITs, suggesting a high penetrance in patients who have undergone TBSE. The most prevalent malignancies among BAP1 mutation carriers were uveal melanoma (n =  60 [28%]), mesothelioma (n = 48 [22%]), cutaneous melanoma (n = 38 [18%]), and renal cell carcinoma (n = 20 [9%]). A total of 71 unique mutations in BAP1 have been reported.

Conclusions and Relevance

Our results indicate that germline mutations in both coding and noncoding regions throughout the BAP1 gene can impair protein function, leading to an increased risk for several associated malignancies. Four of the 8 probands we present had no history of BAP1-associated malignancies and were assessed for germline mutations when found to have MBAITs on dermatologic examination. Dermatologists can identify patients with a high likelihood of the BAP1 cancer syndrome through personal and family history and TBSE for the presence of possible MBAITs.

More Than Many: How to Manage the Most Frequent Cancer?

Leiter et al. report on the increasing incidence of keratinocyte cancers in Germany. The true population burden is even larger then reported, because many of these new patients will develop multiple keratinocyte cancers. Keratinocyte cancer puts a large burden on health care systems worldwide. Prevention and management strategies are needed to maintain high quality of care for all patients.

Smokers versus Smoking: Is There Detection Bias for Keratinocyte Carcinomas?

Dusingize et al. used a prospective observational cohort study to demonstrate a decreased risk of basal cell carcinoma and an increased risk of squamous cell carcinoma among smokers. This association disappeared after stratifying for skin screening visits, demonstrating the important role of detection bias. In the absence of randomized clinical trials, well-designed and critically analyzed observational studies can provide similarly valuable evidence.

Occurrence of metachronous basal cell carcinomas: a prognostic model

BACKGROUND

A third of patients with a first basal cell carcinoma (BCC) will develop subsequent (metachronous) BCCs.

OBJECTIVES

To study the prognostic effect of the number of previous BCC diagnosis dates a patient has experienced to derive a prediction model to assess the risk of metachronous BCCs that may inform individualized decision making on surveillance.

METHODS

We considered participants of north-western European ancestry from a prospective population-based cohort study (Rotterdam Study). After linkage with the Dutch Pathology Registry, 1077 patients with a first BCC were included. Candidate predictors for metachronous BCCs included patient, lifestyle and tumour characteristics. The prognostic model was developed with Fine and Gray regression analysis to account for competing risk of death. We used bootstrapping to correct for within-patient correlation and statistical optimism in predictive performance.

RESULTS

Second to fifth BCCs occurred in 293, 122, 58 and 36 patients, with median follow-up times of 3·0, 2·1, 1·7 and 1·8 years after the previous BCC, respectively. The risk of a new BCC was higher for patients with more metachronous BCCs. Having more than one BCC at diagnosis was another strong predictor of metachronous BCCs. Discriminative ability of the model was reasonable with an optimism-corrected c-index of 0·70 at 3 years.

CONCLUSIONS

The number of previous BCC diagnosis dates was a strong prognostic factor and should be considered when predicting the risk of metachronous BCCs. When the number of previous BCC diagnosis dates is combined with other readily available characteristics into a prognostic model, patients at high risk of a new BCC can be identified.

Genome-Wide Association Studies of Multiple Keratinocyte Cancers

There is strong evidence for a role of environmental risk factors involved in susceptibility to develop multiple keratinocyte cancers (mKCs), but whether genes are also involved in mKCs susceptibility has not been thoroughly investigated. We investigated whether single nucleotide polymorphisms (SNPs) are associated with susceptibility for mKCs. A genome-wide association study (GWAS) of 1,666 cases with mKCs and 1,950 cases with single KC (sKCs; controls) from Harvard cohorts (the Nurses' Health Study [NHS], NHS II, and the Health Professionals Follow-Up Study) and the Framingham Heart Study was carried-out using over 8 million SNPs (stage-1). We sought to replicate the most significant statistical associations (p-value≤ 5.5x10-6) in an independent cohort of 574 mKCs and 872 sKCs from the Rotterdam Study. In the discovery stage, 40 SNPs with suggestive associations (p-value ≤5.5x10-6) were identified, with eight independent SNPs tagging all 40 SNPs. The most significant SNP was located at chromosome 9 (rs7468390; p-value = 3.92x10-7). In stage-2, none of these SNPs replicated and only two of them were associated with mKCs in the same direction in the combined meta-analysis. We tested the associations for 19 previously reported basal cell carcinoma-related SNPs (candidate gene association analysis), and found that rs1805007 (MC1R locus) was significantly associated with risk of mKCs (p-value = 2.80x10-4). Although the suggestive SNPs with susceptibility for mKCs were not replicated, we found that previously identified BCC variants may also be associated with mKC, which the most significant association (rs1805007) located at the MC1R gene.