Spectrum of Immune-Related Conditions Associated with Risk of Keratinocyte Cancers among Elderly Adults in the United States

Cutaneous squamous cell carcinoma tumor accrual rates in immunosuppressed patients with autoimmune and inflammatory conditions: A retrospective cohort study

BACKGROUND

Immunosuppression is a known risk factor for the development of cutaneous squamous cell carcinoma (CSCC), especially in solid organ transplant recipients and chronic lymphocytic leukemia. However, this risk is less well defined in autoimmune and inflammatory conditions.

OBJECTIVE

Assess the impact that disease-type, duration of immunosuppression, and systemic medications have on CSCC accrual rates, defined as the number of CSCCs a patient develops per year, in autoimmune and inflammatory conditions.

METHODS

Retrospective review of 94 immunosuppressed (rheumatoid arthritis: 31[33.0%], inflammatory bowel disease: 17[18.1%], psoriasis: 11[11.7%], autoimmune other (AO): 24[25.5%], inflammatory other: 21[22.3%]) and 188 immunocompetent controls to identify all primary, invasive CSCCs diagnosed from 2010 to 2020.

RESULTS

Immunosuppressed patients had higher CSCC accrual rates than immunocompetent controls (0.44 ± 0.36): total cohort (0.82 ± 0.95, P < .01), rheumatoid arthritis (0.88 ± 1.10, P < .01), inflammatory bowel disease (0.94 ± 0.88, P < .01), psoriasis (1.06 ± 1.58, P < .01), AO (0.72 ± 0.56, P < .01), and inflammatory other (0.72 ± 0.61, P < .01). There was an association between increased tumor accrual rates and exposure to systemic medications including, immunomodulators, tumor necrosis factor-alpha inhibitors, non-tumor necrosis factor inhibitor biologics, and corticosteroids, but not with number of systemic medication class exposures or duration of immunosuppression.

LIMITATIONS

Retrospective, singlecenter study.

CONCLUSION

Patients with autoimmune and inflammatory conditions accrue CSCCs at higher rates than immunocompetent patients.

Incorporation of the 40-Gene Expression Profile (40-GEP) Test to Improve Treatment Decisions in High-Risk Cutaneous Squamous Cell Carcinoma (cSCC) Patients: Case Series and Algorithm

Cutaneous squamous cell carcinoma (cSCC) has become a significant public health issue due to its rapidly rising incidence and an estimated 1.8 million newly diagnosed cases annually. As with other cancers, treatment decisions for patients with cSCC are based primarily on a patient's risk for poor outcomes. There has been improvement in clinicopathologic factor-based risk assessment approaches, either through informal methods or ever evolving staging approaches. However, these approaches misidentify patients who will eventually have disease progression as low-risk and conversely, over classify patients as high-risk who do not experience relapse. To improve the accuracy of risk assessment for patients with cSCC, the 40-gene expression profile (40-GEP) test has been validated to show statistically significant stratification of a high-risk cSCC patient's risk of nodal or distant metastasis, independent of currently available risk-assessment methods. The 40-GEP test allows for a more accurate classification of metastatic risk for high-risk cSCC patients, with the aim to influence appropriate allocation of clinician time and therapeutic resources to those patients who will most benefit. The objective of this article is to present a treatment algorithm in which clinicians can easily integrate the results of the 40-GEP test into their current treatment approaches to tailor patient care based on individual tumor biology. The following modalities were considered: surveillance imaging, sentinel lymph node biopsy (SLNB), adjuvant radiation therapy (ART), and clinical follow-up. The authors have contributed their own cases for discussion as to how they have seen the beneficial impact of 40-GEP test results in their own practice. Overall, clinicians can identify risk-aligned treatment pathway improvements with the use of the 40-GEP test for challenging to manage, high-risk cSCC patients.

Atezolizumab for the treatment of advanced recurrent basal cell carcinoma and urothelial carcinoma of bladder: a case report

BACKGROUND

The use of checkpoint inhibitors has become increasingly important in the treatment of different cancers, including advanced muscle-invasive urothelial cancer and even in basal cell carcinoma. We present the case of a patient with advanced basal cell carcinoma and metastatic muscle-invasive urothelial cancer, who was treated with the programmed death-ligand 1 inhibitor, atezolizumab for both cancers.

CASE PRESENTATION

A 72-year-old Caucasian female patient, with a history of smoking without any comorbidities developed periocular basal cell carcinoma, which was surgically removed but relapsed 4 years later. Surgical excision was carried out twice, but with positive margins, therefore definitive radiotherapy was given. Subsequently, the patient developed non-muscle-invasive papillary urothelial carcinoma, which was removed by transurethral resection. Follow-up was irregular owing to the patient's inadequate compliance, and within 2 years, the patient's cancer relapsed and histology confirmed muscle-invasive urothelial carcinoma. Definitive radiochemotherapy was not accepted by the patient. Meanwhile, the patient's basal cell carcinoma had also progressed, despite receiving vismodegib therapy. Therefore, the patient was administered epirubicin-cisplatin. Having reached the maximum cumulative dose of epirubicin, treatment with this chemotherapeutic agent could not be continued. The patient developed bladder cancer metastasis in her left suprainguinal lymph nodes. Owing to the presence of both types of tumors, programmed death-ligand 1 inhibitor atezolizumab treatment was chosen. In just over 1 year, the patient received 17 cycles of atezolizumab altogether, which was tolerated well without any adverse or side effects. Follow-up imaging scans indicated complete remission of the metastatic bladder cancer and stable disease of the basal cell carcinoma. The patient subsequently passed away in hospital due to a complication of COVID-19 infection.

CONCLUSIONS

Our patient attained stable disease in advanced basal cell carcinoma and complete remission in metastatic muscle-invasive urothelial cancer after receiving programmed death-ligand 1 inhibitor, atezolizumab, therapy. To our knowledge, this is the first paper to report the use of programmed death-ligand 1 inhibitor, atezolizumab, as treatment for advanced basal cell carcinoma. This case may also be of interest for clinicians when treating patients with two synchronous cancers.

Immune-related conditions and cancer-specific mortality among older adults with cancer in the United States

Immunity may play a role in preventing cancer progression. We studied associations of immune-related conditions with cancer-specific mortality among older adults in the United States. We evaluated 1 229 443 patients diagnosed with 20 common cancer types (age 67-99, years 1993-2013) using Surveillance Epidemiology and End Results-Medicare data. With Medicare claims, we ascertained immune-related medical conditions diagnosed before cancer diagnosis (4 immunosuppressive conditions [n = 3380 affected cases], 32 autoimmune conditions [n = 155 766], 3 allergic conditions [n = 101 366]). For each cancer site, we estimated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for cancer-specific mortality associated with each condition, applying a Bonferroni cutoff for significance (P < 5.1 × 10-5 ). Bayesian metaanalysis methods were used to detect patterns across groups of conditions and cancers. We observed 21 associations with cancer-specific mortality at the Bonferroni threshold. Increased cancer-specific mortality was observed with rheumatoid arthritis for patients with melanoma (aHR 1.51, 95% CI 1.31-1.75) and breast cancer (1.24, 1.15-1.33)), and with hemolytic anemia for bladder cancer (2.54, 1.68-3.82). Significant inverse associations with cancer-specific mortality were observed for allergic rhinitis (range of aHRs: 0.84-0.94) and asthma (0.83-0.95) for cancers of the lung, breast, and prostate. Cancer-specific mortality was nominally elevated in patients with immunosuppressive conditions for eight cancer types (aHR range: 1.27-2.36; P-value range: 7.5 × 10-5 to 3.1 × 10-2 ) and was strongly associated with grouped immunosuppressive conditions using Bayesian metaanalyses methods. For older patients with several cancer types, certain immunosuppressive and autoimmune conditions were associated with increased cancer-specific mortality. In contrast, inverse associations with allergic conditions may reflect enhanced immune control of cancer.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of nonmelanoma skin cancer

Nonmelanoma skin cancers (NMSCs) are some of the most commonly diagnosed malignancies. In general, early-stage NMSCs have favorable outcomes; however, a small subset of patients develop resistant, advanced, or metastatic disease, or aggressive subtypes that are more challenging to treat successfully. Recently, immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration (FDA) for the treatment of Merkel cell carcinoma (MCC), cutaneous squamous cell carcinoma (CSCC), and basal cell carcinoma (BCC). Although ICIs have demonstrated activity against NMSCs, the routine clinical use of these agents may be more challenging due to a number of factors including the lack of predictive biomarkers, the need to consider special patient populations, the management of toxicity, and the assessment of atypical responses. With the goal of improving patient care by providing expert guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). The expert panel drew on the published literature as well as their own clinical experience to develop recommendations for healthcare professionals on important aspects of immunotherapeutic treatment for NMSCs, including staging, biomarker testing, patient selection, therapy selection, post-treatment response evaluation and surveillance, and patient quality of life (QOL) considerations, among others. The evidence- and consensus-based recommendations in this CPG are intended to provide guidance to cancer care professionals treating patients with NMSCs.

Macrophage and T-Cell Infiltration and Topographic Immune Cell Distribution in Non-Melanoma Skin Cancer of the Head and Neck

Non-melanoma skin cancer (NMSC) is a heterogeneous tumor entity that is vastly determined by age and UV-light exposure leading to a great mutational burden in cancer cells. However, the success of immune checkpoint blockade in advanced NMSC and the incidence and disease control rates of NMSC in organ transplant recipients compared to immunologically uncompromised patients point toward the emerging importance of the immunologic activity of NMSC. To gain first insight into the role of T-cell and macrophage infiltration in NMSC of the head and neck and capture their different immunogenic profiles, which appear to be highly relevant for the response to immunotherapy, we conducted a whole slide analysis of 107 basal cell carcinoma (BCC) samples and 117 cutaneous squamous cell carcinoma (cSCC) samples. The CD8⁺ and CD68⁺ immune cell expression in both cancer types was evaluated by immunohistochemistry and a topographic distribution profile, and the proportion of both cell populations within the two tumor entities was assessed. The results show highly significant differences in terms of CD8⁺ T-cell and CD68⁺ macrophage infiltration in BCC and cSCC and indicate cSCC as a highly immunogenic tumor. Yet, BCC presents less immune cell infiltration; the relation between the immune cells compared to cSCC does not show any significant difference. These findings help explain disparities in local aggressiveness, distant metastasis, and eligibility for immune checkpoint blockade in both tumor entities and encourage further research.

Polygenic Risk Scores Stratify Keratinocyte Cancer Risk among Solid Organ Transplant Recipients with Chronic Immunosuppression in a High Ultraviolet Radiation Environment

Solid organ transplant recipients (SOTRs) have elevated risks for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), especially in high UVR environments. We assessed whether polygenic risk scores can improve the prediction of BCC and SCC risks and multiplicity over and above the traditional risk factors in SOTRs in a high UV setting. We built polygenic risk scores for BCC (n = 594,881) and SCC (n = 581,431) using UK Biobank and 23andMe datasets, validated them in the Australian QSkin Sun and Health Study cohort (n > 6,300), and applied them in SOTRs in the skin tumor in allograft recipients cohort from Queensland, Australia, a high UV environment. About half of the SOTRs with a high genetic risk developed BCC (absolute risk = 45.45%, 95% confidence interval = 33.14-58.19%) and SCC (absolute risk = 44.12%, 95% confidence interval = 32.08-56.68%). For both cancers, SOTRs in the top quintile were at >3-fold increased risk relative to those in the bottom quintile. The respective polygenic risk scores improved risk predictions by 2% for BCC (area under the curve = 0.77 vs. 0.75, P = 0.0691) and SCC (area under the curve = 0.84 vs. 0.82, P = 0.0260), over and above the established risk factors, and 19.03% (for BCC) and 18.10% (for SCC) of the SOTRs were reclassified in a high/medium/low risk scenario. The polygenic risk scores also added predictive accuracy for tumor multiplicity (BCC R2 = 0.21 vs. 0.19, P = 3.2 × 10-3; SCC R2 = 0.30 vs. 0.27, P = 4.6 × 10-4).

Non-Melanoma Skin Cancer in People Living With HIV: From Epidemiology to Clinical Management

Skin cancers represent the most common human tumors with a worldwide increasing incidence. They can be divided into melanoma and non-melanoma skin cancers (NMSCs). NMSCs include mainly squamous cell (SCC) and basal cell carcinoma (BCC) with the latest representing the 80% of the diagnosed NMSCs. The pathogenesis of NMSCs is clearly multifactorial. A growing body of literature underlies a crucial correlation between skin cancer, chronic inflammation and immunodeficiency. Intensity and duration of immunodeficiency plays an important role. In immunocompromised patients the incidence of more malignant forms or the development of multiple tumors seems to be higher than among immunocompetent patients. With regards to people living with HIV (PLWH), since the advent of combined antiretroviral therapy (cART), the incidence of non-AIDS-defining cancers (NADCs), such as NMSCs, have been increasing and now these neoplasms represent a leading cause of illness in this particular population. PLWH with NMSCs tend to be younger, to have a higher risk of local recurrence and to have an overall poorer outcome. NMSCs show an indolent clinical course if diagnosed and treated in an early stage. BCC rarely metastasizes, while SCC presents a 4% annual incidence of metastasis. Nevertheless, metastatic forms lead to poor patient outcome. NMSCs are often treated with full thickness treatments (surgical excision, Mohs micro-graphic surgery and radiotherapy) or superficial ablative techniques (such as cryotherapy, electrodesiccation and curettage). Advances in genetic landscape understanding of NMSCs have favored the establishment of novel therapeutic strategies. Concerning the therapeutic evaluation of PLWH, it’s mandatory to evaluate the risk of interactions between cART and other treatments, particularly antiblastic chemotherapy, targeted therapy and immunotherapy. Development of further treatment options for NMSCs in PLWH seems needed. We reviewed the literature after searching for clinical trials, case series, clinical cases and available databases in Embase and Pubmed. We review the incidence of NMSCs among PLWH, focusing our attention on any differences in clinicopathological features of BCC and SCC between PLWH and HIV negative persons, as well as on any differences in efficacy and safety of treatments and response to immunomodulators and finally on any differences in rates of metastatic disease and outcomes.

Lifetime Ambient UV Radiation Exposure and Risk of Basal Cell Carcinoma by Anatomic Site in a Nationwide U.S. Cohort, 1983-2005

BACKGROUND

Cutaneous basal cell carcinoma (BCC) has long been associated with UV radiation (UVR) exposure, but data are limited on risks by anatomic site.

METHODS

We followed 63,912 cancer-free White U.S. radiologic technologists from cohort entry (1983-1989/1994-1998) to exit (date first BCC via 2003-2005 questionnaire). We estimated associations between cumulative ambient UVR and relative/absolute risks of self-reported BCC by anatomic location via Poisson models.

RESULTS

For incident first primary BCC in 2,124 subjects (mean follow-up, 16.9 years) log[excess relative risks] (ERR) of BCC per unit cumulative ambient UVR = 1.27/MJ cm^-2 [95% confidence interval (CI): 0.86-1.68; P _trend < 0.001] did not vary by anatomic site (P = 0.153). However, excess absolute risks of BCC per unit cumulative ambient UVR were large for the head/neck = 5.46/MJ cm^-2/10⁴ person-year (95% CI: 2.92-7.36; P _trend < 0.001), smaller for the trunk (2.56; 95% CI: 1.26-3.33; P _trend = 0.003), with lesser increases elsewhere. There were lower relative risks, but higher absolute risks, for those with Gaelic ancestry (P < 0.001), also higher absolute risks among those with fair complexion, but relative and absolute risks were not generally modified by other constitutional, lifestyle or medical factors for any anatomic sites. Excess absolute and relative risk was concentrated 5-15 years before time of follow-up.

CONCLUSIONS

BCC relative and absolute risk rose with increasing cumulative ambient UVR exposure, with absolute risk highest for the head/neck, to a lesser extent in the trunk.

IMPACT

These associations should be evaluated in other White and other racial/ethnic populations along with assessment of possible modification by time outdoors, protective, and behavioral factors.

Immunologic Characteristics of Nonmelanoma Skin Cancers: Implications for Immunotherapy

In this review, we summarize the immunology of nonmelanoma skin cancers (NMSCs) and the clinical data with immunotherapy in this heterogeneous group of cancers that include basal cell carcinoma (BCC), cutaneous squamous cell carcinoma (CSCC), and Merkel cell carcinoma (MCC). NMSCs are exceedingly common, and their treatment consumes substantial health care resources. Annual global mortality from NMSCs is comparable to that from malignant melanoma. Although the majority of NMSCs are localized at diagnosis and are treated effectively with surgery, metastases (nodal and distant) can sometimes arise and require systemic therapy. Given the success of immunotherapy in treating cutaneous melanoma, there has been an increasing interest in studying the immunology of NMSCs. Immunocompromised patients have a substantially higher risk of developing NMSCs (particularly CSCC and MCC), suggesting a role of the immune system in the pathogenesis of these cancers. Similar to cutaneous melanoma, the pathogenesis of BCC, CSCC, and virus-negative MCC is related to DNA damage from ultraviolet radiation exposure, and these cancers have a very high tumor mutational burden, which likely results in higher levels of tumor neoantigens that may be targets for the immune system. Viral antigens in virus-positive MCC are also strongly immunogenic. Emerging data from clinical trials of immune checkpoint inhibitors in NMSCs look very promising and are rapidly changing the treatment landscape of these cancers. Specifically, pembrolizumab and avelumab are U.S. Food and Drug Administration-approved for treatment of metastatic MCC and cemiplimab for metastatic CSCC. Several ongoing trials are investigating novel immunotherapies (monotherapies as well as combination) for treatment of NMSCs.

Molecular genetics of cutaneous squamous cell carcinoma: perspective for treatment strategies

Cutaneous squamous cell carcinoma (cSCC) represents 20% of all skin cancers. Although primary cSCCs can be successfully treated with surgery, a subset of highly aggressive lesions may progress to advanced disease, representing a public healthcare problem with significant cancer-related morbidity and mortality. A complex network of genes (TP53, CDKN2A, NOTCH1 and NOTCH2, EGFR and TERT) and molecular pathways (RAS/RAF/MEK/ERK and PI3K/AKT/mTOR) have been shown to play an important role in the pathogenesis of cSCC. The epigenetic regulation of TP53 and CDKN2A is an attractive therapeutic target for the treatment of cSCC, as well as NOTCH-activating agents capable to restore its tumour-suppressor function. EGFR inhibitors including both monoclonal antibodies (cetuximab and panitumumab) and tyrosine kinase inhibitors (erlotinib, gefitinib and dasatinib) have been used in clinical trials for the treatment of advanced cSCC, achieving only partial clinical benefit. Recently, an immune-modulatory drug (cemiplimab) has been introduced for the treatment of advanced cSCC with good clinical results and a favourable safety profile, while other PD1/PD-L1 inhibitors, either as monotherapy or in combination with targeted therapies, are currently under investigation. This review focuses on molecular findings involved in the pathogenesis of cSCC and their implications for the future development of new treatment strategies. In addition, current and ongoing treatments on targeted therapies and/or immunotherapy are illustrated.

Epidemiologic perspectives on immunosuppressed populations and the immunosurveillance and immunocontainment of cancer

The advent in the last several years of effective immunotherapy for cancer has renewed interest in the role of the immune system in controlling cancer. The idea that the immune system can help control cancer has a long history. Solid organ transplant recipients (SOTRs) as well as human immunodeficiency virus (HIV)-infected people are affected by cell-mediated immune dysfunction. Epidemiologic studies of these populations reveal a pattern characterized by a strongly increased incidence of virus-related cancers (eg, Kaposi sarcoma, non-Hodgkin lymphoma, and anogenital cancers). In addition, recent epidemiologic studies have evaluated cancer-specific mortality among SOTRs and HIV-infected people following a cancer diagnosis. For a wider range of cancers-not limited to those caused by viruses, and including melanoma and cancers of the colorectum, lung, and breast- these immunosuppressed cancer patients have higher cancer-specific mortality than other cancer patients. This latter group of cancers somewhat mirrors those for which immunotherapy with checkpoint inhibitors is approved. These epidemiologic observations suggest that there are 2 distinct immune selection processes in humans: immunosurveillance directed against premalignant cells before cancer diagnosis (most relevant for preventing virus-related cancers), and "immunocontainment" directed against established cancers. These processes thus appear relevant for different groups of malignancies and may have different mechanisms.

Keratinocyte Carcinomas: Current Concepts and Future Research Priorities

Cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC) are keratinocyte carcinomas, the most frequently diagnosed cancers in fair-skinned populations. Ultraviolet radiation (UVR) is the main driving carcinogen for these tumors, but immunosuppression, pigmentary factors, and aging are also risk factors. Scientific discoveries have improved the understanding of the role of human papillomaviruses (HPV) in cSCC as well as the skin microbiome and a compromised immune system in the development of both cSCC and BCC. Genomic analyses have uncovered genetic risk variants, high-risk susceptibility genes, and somatic events that underlie common pathways important in keratinocyte carcinoma tumorigenesis and tumor characteristics that have enabled development of prediction models for early identification of high-risk individuals. Advances in chemoprevention in high-risk individuals and progress in targeted and immune-based treatment approaches have the potential to decrease the morbidity and mortality associated with these tumors. As the incidence and prevalence of keratinocyte carcinoma continue to increase, strategies for prevention, including effective sun-protective behavior, educational interventions, and reduction of tanning bed access and usage, are essential. Gaps in our knowledge requiring additional research to reduce the high morbidity and costs associated with keratinocyte carcinoma include better understanding of factors leading to more aggressive tumors, the roles of microbiome and HPV infection, prediction of response to therapies including immune checkpoint blockade, and how to tailor both prevention and treatment to individual risk factors and needs.

Risk of Kaposi sarcoma after solid organ transplantation in the United States

Due to treatment with immunosuppressive medications, solid organ transplant recipients have elevated risk for Kaposi sarcoma (KS), which is caused by human herpesvirus 8 (HHV8). Other risk factors for KS are poorly understood. We linked the United States solid organ transplant registry with 17 population-based cancer registries to ascertain KS incidence among 244,964 transplant recipients from 1987-2014. To compare incidence rates of KS according to patient and transplant characteristics, we calculated incidence rate ratios (IRRs) using Poisson regression. To compare associations of KS with other skin cancers occurring before or within 12 months of KS diagnosis, we computed odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression. All statistical tests were two-sided. We identified 163 KS cases during follow-up. Among transplant recipients, we found significantly increased risk of KS associated with male sex (IRR = 1.87; 95%CI:1.32,2.71), nonwhite race (IRR = 2.67; 95%CI:1.92,3.72), non-US citizenship (IRR = 2.10; 95%CI:1.19,3.47), lung transplant (IRR = 2.22; 95%CI:1.03,4.24, vs. kidney), and older age at transplant. KS risk decreased significantly with time since transplant and recent calendar year, however, no specific induction or maintenance medication was associated with KS. KS incidence was not significantly associated with ambient ultraviolet radiation (IRR = 1.32 95%CI:0.87,2.02, tertile 3 vs. 1). KS incidence has decreased in recent calendar years. In a cross-sectional sample, we found cutaneous squamous cell carcinoma was associated with KS (OR = 4.83; 95%CI:1.30,14.69). KS risk factors included those potentially associated with HHV8 infection and increased immunosuppression. Our findings suggest that transplant recipients with a non-KS skin cancer may also be at high KS risk.

The importance and implications of comparator selection in pharmacoepidemiologic research

PURPOSE OF REVIEW

Pharmacoepidemiologic studies employing large databases are critical to evaluating the effectiveness and safety of drug exposures in large and diverse populations. Because treatment is not randomized, researchers must select a relevant comparison group for the treatment of interest. The comparator group can consist of individuals initiating: (1) a similarly indicated treatment (active comparator), (2) a treatment used for a different indication (inactive comparator) or (3) no particular treatment (non-initiators). Herein we review recent literature and describe considerations and implications of comparator selection in pharmacoepidemiologic studies.

RECENT FINDINGS

Comparator selection depends on the scientific question and feasibility constraints. Because pharmacoepidemiologic studies rely on the choice to initiate or not initiate a specific treatment, rather than randomization, they are at-risk for confounding related to the comparator choice including: by indication, disease severity and frailty. We describe forms of confounding specific to pharmacoepidemiologic studies and discuss each comparator along with informative examples and a case study. We provide commentary on potential issues relevant to comparator selection in each study, highlighting the importance of understanding the population in whom the treatment is given and how patient characteristics are associated with the outcome.

SUMMARY

Advanced statistical techniques may be insufficient for reducing confounding in observational studies. Evaluating the extent to which comparator selection may mitigate or induce systematic bias is a critical component of pharmacoepidemiologic studies.

Cross-Talk between Wnt and Hh Signaling Pathways in the Pathology of Basal Cell Carcinoma

Basal cell carcinoma (BCC) is the most frequently occurring form of all cancers. The cost of care for BCC is one of the highest for all cancers in the Medicare population in the United States. Activation of Hedgehog (Hh) signaling pathway appears to be a key driver of BCC development. Studies involving mouse models have provided evidence that activation of the glioma-associated oncogene (GLI) family of transcription factors is a key step in the initiation of the tumorigenic program leading to BCC. Activation of the Wnt pathway is also observed in BCCs. In addition, the Wnt signaling pathway has been shown to be required in Hh pathway-driven development of BCC in a mouse model. Cross-talks between Wnt and Hh pathways have been observed at different levels, yet the mechanisms of these cross-talks are not fully understood. In this review, we examine the mechanism of cross-talk between Wnt and Hh signaling in BCC development and its potential relevance for treatment. Recent studies have identified insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), a direct target of the Wnt/&beta;-catenin signaling, as the factor that binds to GLI1 mRNA and upregulates its levels and activities. This mode of regulation of GLI1 appears important in BCC tumorigenesis and could be explored in the treatment of BCCs.

A Patient with Multiple Keratinocytic Cancers (MKC): Uncommon Presentation in a Bulgarian Patient

Keratinocyte skin cancers, including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are the most common cancer occurring in people with fair skin, worldwide. Despite all known triggers, several suggested contributors are still investigated. We will focus our attention on the personal history of previous cancers and radiation exposure as occupational risk factors, as in the presented case. We report a patient, with multiple BCCs, and subsequent occurrence of a SCC on photo-exposed area of the face, as we want to emphasize the importance of strict following up of these patients, regarding the risk for developing new tumors in short periods of time, no matter if the triggering exposure factor is known from the history, or not. Although keratinocytes tumours are associated with the low mortality rate, we focus the attention on the fact, that the history of non-melanoma skin cancer is associated with increased mortality.