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We previously showed that inhibition of glycolysis in cutaneous squamous cell carcinoma (SCC)-initiating cells had no effect on tumorigenesis, despite the perceived requirement of the Warburg effect, which was thought to drive carcinogenesis. Instead, these SCCs were metabolically flexible and sustained growth through glutaminolysis, another metabolic process frequently implicated to fuel tumorigenesis in various cancers. Here, we focused on glutaminolysis and genetically blocked this process through glutaminase (GLS) deletion in SCC cells of origin. Genetic deletion of GLS had little effect on tumorigenesis due to the up-regulated lactate consumption and utilization for the TCA cycle, providing further evidence of metabolic flexibility. We went on to show that posttranscriptional regulation of nutrient transporters appears to mediate metabolic flexibility in this SCC model. To define the limits of this flexibility, we genetically blocked both glycolysis and glutaminolysis simultaneously and found the abrogation of both of these carbon utilization pathways was enough to prevent both papilloma and frank carcinoma.

PURPOSE: Merkel cell carcinoma (MCC) is an aggressive skin cancer with a 40% recurrence rate, lacking effective prognostic biomarkers and surveillance methods. This prospective, multicenter, observational study aimed to evaluate circulating tumor DNA (ctDNA) as a biomarker for detecting MCC recurrence. METHODS: Plasma samples, clinical data, and imaging results were collected from 319 patients. A tumor-informed ctDNA assay was used for analysis. Patients were divided into discovery (167 patients) and validation (152 patients) cohorts. Diagnostic performance, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), was assessed. RESULTS: ctDNA showed high sensitivity, 95% (discovery; 95% CI, 87 to 99) and 94% (validation; 95% CI, 85 to 98), for detecting disease at enrollment, with corresponding specificities of 90% (95% CI, 82 to 95) and 86% (95% CI, 77 to 93). A positive ctDNA during surveillance indicated increased recurrence risk, with hazard ratios (HRs) of 6.8 (discovery; 95% CI, 2.9 to 16) and 20 (validation; 95% CI, 8.3 to 50). The PPV for clinical recurrence at 1 year after a positive ctDNA test was 69% (discovery; 95% CI, 32 to 91) and 94% (validation; 95% CI, 71 to 100), respectively. The NPV at 135 days after a negative ctDNA test was 94% (discovery; 95% CI, 90 to 97) and 93% (validation; 95% CI, 89 to 97), respectively. Patients positive for ctDNA within 4 months after treatment had higher rates of recurrence, with 1-year rates of 74% versus 21% (adjusted HR, 7.4 [95% CI, 2.7 to 20]). CONCLUSION: ctDNA testing exhibited high prognostic accuracy in detecting MCC recurrence, suggesting its potential to reduce frequent surveillance imaging. ctDNA also identifies high-risk patients who need more frequent imaging and may be best suited for adjuvant therapy trials.

Actinic keratosis (AK) is a common precancerous skin condition predominantly affecting older males with fair skin and significant UV exposure. The clinical significance of AK is related to its potential for malignant transformation and progression to squamous cell carcinoma (SCC). Accurate diagnosis of AK is essential for adequate treatment, evaluation of therapeutic efficacy, and mitigating the risk of developing SCC. However, clinician variability due to the subjective nature of current diagnostic tools presents significant challenges to achieving consistent and reliable AK diagnoses. Thus, there is no universally accepted standard for measuring AK.This review evaluates current methods for evaluating and diagnosing AK, focusing on clinician variability through inter- and intraobserver agreement. Eight peer-reviewed studies investigating the reliability of various approaches for AK evaluation show substantial variability in interobserver or intraobserver agreement, with most methods demonstrating only slight to moderate reliability. Some suggest that consensus discussions and simplified rating scales can modestly improve diagnostic reliability. However, remaining variability and the lack of a universally accepted standard for measuring AK underscore the need for more robust and standardized diagnostic and evaluation methods.The review emphasizes the need for improved diagnostic tools and standardized methods to enhance the accuracy and reliability of AK assessments. It also proposes applying a novel examination approach using 1,3-dihydroxyacetone (DHA) staining which may improve the visualization and identification of AK lesions. Advancements in these areas have significant potential, promising better clinical practices and patient outcomes in AK management.