BACKGROUND:Circulating tumor DNA (ctDNA) is a promising biomarker to predict recurrence in solid tumors such as colorectal and breast cancer. Defining complete response after chemoradiation remains challenging, as post-treatment inflammatory and tissue changes limit clinical and imaging evaluation. METHODS:The authors conducted a prospective longitudinal study of patients with localized cervical and anal cancer treated with curative-intent chemoradiation with the aim of evaluating the role of ctDNA as a predictor of recurrence. Blood specimens were collected at D1, D29, immediately post-treatment, 8-weeks, 24-weeks, and every 6-months up to 5-years. ctDNA testing (Signatera™) was provided by Natera as an in-kind donation. The primary endpoint was correlation between 8-week ctDNA and recurrence. RESULTS:28 patients were evaluable. Ten recurrences occurred, all in patients with positive ctDNA after chemoradiation and before radiologic progression. The median interval between ctDNA positivity and radiologic progression was 3.0-months (range 0.5-21.3). All patients with radiologic complete response at 6 months had negative 8-week ctDNA. Among those without complete response, 8-week ctDNA identified most who later progressed (6/8), while all without complete response who did not progress had negative ctDNA. Eight-week ctDNA positivity was strongly associated with inferior progression-free survival: median 6.7-months in ctDNA-positive versus not reached in ctDNA-negative patients (HR = 40.09, p = 0.001). CONCLUSION:Among patients with cervical and anal cancer, ctDNA monitoring after definitive chemoradiation identifies individuals without complete response and predicts recurrence. ctDNA positivity at 8-weeks identifies a very high-risk group for whom treatment intensification trials are warranted.

Dengue fever challenges public health worldwide. The numerous factors associated with dengue fever severity and mortality risk include host characteristics such as patient age, comorbid conditions, previous dengue virus (DENV) infections, and biochemical biomarkers. Type I IFNs are essential cytokines in orchestrating innate and adaptive immune responses against viral invasion, and their regulation is mediated by IRF-2, which prevents excessive IFN expression. In vitro studies have shown DENV evasion strategies that affect IFN-I production but few have considered the in-situ interrelationship between IFN-I and the virus. This study aims to find elements of innate immunity that induce the anti-viral response and their correlation with the detected alterations in liver lesions. Liver specimens from individuals who died due to dengue were selected according to clinical and laboratory data and serological diagnosis. The specimens were subjected to histological and immunohistochemical evaluation of cells expressing IFN-I, RIG-1, IRF-2, and STING. Viral antigens were detected by an anti-DENV. A high number of cells expressed RIG-1 and IRF-2 when compared to IFN-I and STING. In severe cases of dengue, DENV may play a role in its pathogenesis with properties that induce non-effective immune responses. The virus can evade effective immune responses by impairing the early activation of innate immunity. This immune dysregulation may contribute to the progression of more severe manifestations and seems to play a role in the pathogenesis of hepatic involvement.

BACKGROUND:The treatment of Gastric Cancer (GC) has evolved with advances in multimodal therapy and minimally invasive surgery. This study aimed to provide an overview of the current treatment and survival outcomes of GC at a public high-volume cancer center during 15 years. METHODS:Patients with gastric adenocarcinoma who underwent any surgical procedure between January 2009 and December 2023 were retrospectively included. To investigate temporal differences in patient characteristics and therapeutic approaches, the case cohort was divided into two time periods: Period I (2009-2016) and II (2016-2023). RESULTS:A total of 1406 patients were included: 741 (52.7 %) were treated in Period I, and 665 (47.3 %) in Period II. The proportion of curative-intent surgeries remained stable (65.2% vs. 65.1), but diagnostic procedures increased (7.3 % vs. 12.2). Overall, 804 (57.2 %) patients underwent potentially curative gastrectomy. In Period II, patients had advanced ASA scores, more advanced clinical staging, and more frequent D1 lymphadenectomy (all p < 0.05). The use of minimally invasive surgery and the number of resected lymph nodes increased (both p < 0.001). Multimodal treatment became more frequent, with increased use of preoperative chemotherapy (p = 0.03). There were no significant differences in postoperative complications or 30- and 90-day mortality rates between the two periods. In multivariable analysis, advanced age, ASA III/IV, total gastrectomy, D1 lymphadenectomy, diffuse/mixed histology, advanced pT stage, and lymph node metastasis were independent factors associated with worse survival (all p < 0.05). CONCLUSION:Over 15 years, treatment evolved toward increased use of minimally invasive and multimodal approaches, with no impact on short-term surgical outcomes.

3141 Background: Cervical and anal canal squamous cell carcinoma (SSC) are a significant health problem in underdevelopment countries. Definitive chemoradiation (CRT) is the standard-of-care (SOC) approach for curative treatment in locally advanced disease. Due to the common substantial local inflammation during CRT, the conventional clinical image cannot identify non-responders early. In this scenario, the evaluation of circulating tumor DNA (ctDNA) is a promising tool for real-time tumor response monitoring. Methods: We performed a prospective multicentric cohort study of patients treated between 2020 and 2023 in tertiary oncologic centers in Brazil to evaluate the role of ctDNA dynamic monitoring in epidermoid cervical (CC) and anal cancer (AC) T1-4, N0-1, M0 by AJCC 8th edition and candidates to complete curative CRT. The cDNA was assessed by Signatera test at D1, D29, immediately post-treatment, 8 weeks (w) post-CRT, 24w post-CRT, every 6 months (m) in the first 1-2 years(y), and yearly at 3-5y of follow-up (FUP). The primary endpoint was to estimate the correlation of ctDNA with a tumoral response assessed by conventional routine image and clinical evaluation at 8w. Secondary endpoints included a correlation between ctDNA results at different time points with progression-free survival (PFS) and overall survival (OS). The predictive potential of the biomarker was evaluated using receiving operating characteristic (ROC) curve analysis. Results: We included 33 patients, and 27 were evaluable with ctDNA, with a median FUP of 10m. The majority were female (n=23, 85.1%), and 3 (11%) were HIV-positive(+). Most patients presented with positive nodes and stage III disease (n=18, 66.6%). In the AC group (n=15), the majority received CRT with capecitabine and cisplatin (n=12, 55.5%); in the CC group (n=12), all pts received cisplatin. All pts tested expressed ctDNA+ before treatment. At 8w, images had a sensitivity of 42.8% and specificity of 100% for disease progression (area under the curve [AUC] 0.714), while ctDNA yielded a sensitivity of 85.7% and specificity of 89.4% (AUC 0.875). The ctDNA+ immediately after CRT ended (32%) was consistent with ctDNA+ at 8w (30.7%) and 24w (30%). Pts with ctDNA+ immediately post CRT have a higher risk of disease progression with PFS of 8.2m in ctDNA+ and not reached in ctDNA- group (HR:17.5; IC95%:1.9-157.3; p=0.01). Data are immature for OS analysis. Conclusions: CtDNA immediately post-CRT has a high predictive value in patients with anal and cervical tumors in early access CRT non-responders, who are at a high risk of disease progression. This biomarker should be considered for tailoring strategies of treatment escalation in this population.

Background Tumor-infiltrating lymphocytes (TILs) play a regulatory role in the tumor-associated immune response and are important in the prognosis and treatment response of several cancers. However, because of its heterogeneity, the prognostic value of TILs in gastric cancer (GC) is still controversial. Thus, this study aimed to investigate the association between the density of TILs and patients' outcomes in GC. Methods Patients with gastric adenocarcinoma who underwent curative intent gastrectomy were retrospectively investigated. The groups for analysis were determined on the basis of TIL intensity and percentage of CD3+ T-cell infiltration by immunohistochemical. Furthermore, Epstein-Barr virus (EBV), microsatellite instability (MSI), T-cell ratio of CD4 to CD8, and programmed death protein ligand 1 (PD-L1) status were evaluated. Results A total of 345 patients were enrolled: 124 patients with GCs (35.9%) were classified as the low-CD3+ TIL group, and 221 patients with GCs (64.1%) were classified as the high-CD3+ TIL group. Poorly differentiated histology (P = .014), EBV-positive status (P < .001), PD-L1-positive status (P = .001), and CD4 < CD8 (P < .001) were associated with high-CD3+ GC. There was no difference regarding MSI status, the degree of tumor invasion (pT), the presence of lymph node metastasis, and pTNM stage between low- and high-CD3+ groups. In survival analysis, the high-CD3+ group had better disease-free survival and overall survival rates than had the low-CD3+ group (P = .055 and P = .041, respectively). In the multivariate analysis, total gastrectomy, lymph node metastasis, advanced pT stage, and low CD3+ levels were independent factors related to worse survival. Conclusion High CD3+ TILs levels were significantly associated with improved survival and could serve as prognostic biomarkers in GC. In addition, CD3+ T-cell infiltration was related to both EBV-positive and PD-L1-positive GC and may assist in the investigation of targets in immunotherapy.

BACKGROUND Anti-programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) immunotherapy has demonstrated promising results on gastric cancer (GC). However, PD-L1 can express differently between metastatic sites and primary tumors (PT). AIM To compare PD-L1 status in PT and matched lymph node metastases (LNM) of GC patients and to determine the correlation between the PD-L1 status and clinicopathological characteristics. METHODS We retrospectively reviewed 284 GC patients who underwent D2-gastrectomy. PD-L1 was evaluated by immunohistochemistry (clone SP142) using the combined positive score. All PD-L1+ PT staged as pN+ were also tested for PD-L1 expression in their LNM. PD-L1(-) GC with pN+ served as the comparison group. RESULTS Among 284 GC patients included, 45 had PD-L1+ PT and 24 of them had pN+. For comparison, 44 PD-L1(-) cases with pN+ were included (sample loss of 4 cases). Of the PD-L1+ PT, 54.2% (13/24 cases) were also PD-L1+ in the LNM. Regarding PD-L1(-) PT, 9.1% (4/44) had PD-L1+ in the LNM. The agreement between PT and LNM had a kappa value of 0.483. Larger tumor size and moderate/severe peritumoral inflammatory response were associated with PD-L1 positivity in both sites. There was no statistical difference in overall survival for PT and LNM according to the PD-L1 status (P = 0.166 and P = 0.837, respectively). CONCLUSION Intra-patient heterogeneity in PD-L1 expression was observed between the PT and matched LNM. This disagreement in PD-L1 status may emphasize the importance of considering different tumor sites for analyses to select patients for immunotherapy.

Category: Respiratory Endoscopy Introduction: Histopathological analyses and classification by the Tumor, Node, Metastasis System (TNM) are key-elements in therapeutic decision-making for non-small cell lung cancer (NSCLC).() Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is effective in obtaining biopsies of hilar and mediastinal lymph nodes (MLN), for tissue collection to mediastinal staging in NSCLC.(,) The assessment of clinically significant genomic alterations in surgically resected primary tumors (PT) and MLN aspirates obtained by EBUS-TBNA can provide valuable insights into the risk of recurrence, [...]

Head and neck squamous cell carcinoma (HNSCC) is well known as a serious health problem worldwide, especially in low-income countries or those with limited resources, such as most countries in Latin America. International guidelines cannot always be applied to a population from a large region with specific conditions. This study established a Latin American guideline for care of patients with head and neck cancer and presented evidence of HNSCC management considering availability and oncologic benefit. A panel composed of 41 head and neck cancer experts systematically worked according to a modified Delphi process on (1) document compilation of evidence-based answers to different questions contextualized by resource availability and oncologic benefit regarding Latin America (region of limited resources and/or without access to all necessary health care system infrastructure), (2) revision of the answers and the classification of levels of evidence and degrees of recommendations of all recommendations, (3) validation of the consensus through two rounds of online surveys, and (4) manuscript composition. The consensus consists of 12 sections: Head and neck cancer staging, Histopathologic evaluation of head and neck cancer, Head and neck surgery—oral cavity, Clinical oncology—oral cavity, Head and neck surgery—oropharynx, Clinical oncology—oropharynx, Head and neck surgery—larynx, Head and neck surgery—larynx/hypopharynx, Clinical oncology—larynx/hypopharynx, Clinical oncology—recurrent and metastatic head and neck cancer, Head and neck surgery—reconstruction and rehabilitation, and Radiation therapy. The present consensus established 48 recommendations on HNSCC patient care considering the availability of resources and focusing on oncologic benefit. These recommendations could also be used to formulate strategies in other regions like Latin America countries.

BACKGROUND & AIMS:Organized colorectal cancer (CRC) screening is not widely practiced in Latin America and the results of regional studies may help overcome barriers for implementation of national screening programs. We aimed to describe the implementation and findings of a fecal immunochemical test (FIT)-based program in Brazil. METHODS:In a prospective population-based study, asymptomatic individuals (50-75 years old) from Sao Paulo city were invited to undergo FIT for CRC screening. Participants with positive FIT (≥10 μg Hb/g feces) were referred for colonoscopy. Subjects were classified into groups according to the presence of CRC, precursor lesions, and other benign findings, possibly related to bleeding. RESULTS:Of a total of 9881 subjects, 7.8% had positive FIT and colonoscopy compliance was 68.9% (n = 535). Boston scale was considered adequate in 99% and cecal intubation rate was 99.4%. CRC was diagnosed in 5.9% of the cases, adenoma in 63.2%, advanced adenoma in 31.4%, and advanced neoplasia in 33.0%. Age was positively associated with CRC (P = .03). Higher FIT concentrations were associated with increased detection of CRC (P < .008), advanced adenoma (P < .001), and advanced neoplasia (P < .001). CONCLUSIONS:Implementation of a FIT-based CRC screening program was feasible in a low-resource setting, and there was a high yield for neoplasia in individuals with a positive FIT. This approach could be used as a model to plan and disseminate organized CRC screening more broadly in Brazil and Latin America.

Background Microsatellite instability (MSI) gastric cancer (GC) generally has a better prognosis than microsatellite-stable (MSS) GC and has been associated with nonsurvival benefit with the addition of chemotherapy (CMT) compared with surgery alone. However, patients with MSI have distinct clinicopathological characteristics. This study aimed to compare the survival outcomes between patients with MSI GC and those with MSS GC. In addition, this study analyzed the survival outcomes of patients with MSI GC who received CMT. Methods This study reviewed all patients with GC who underwent curative gastrectomy. Patients were divided into MSI group and the MSS group. Propensity score matching (PSM) was used to match clinicopathological factors. Results Among the 378 patients enrolled, 78 (20.6%) had MSI. Older age (P < .001), subtotal gastrectomy (P = .008), pN0 (P = .020), and earlier pTNM stage (P = .012) were associated with MSI GC. Survival analysis showed better disease-free survival (DFS) and overall survival (OS) of patients in the MSI group (P = .012 and P = .019, respectively). After PSM, 78 patients were matched to each group. All variables assigned to the scores were well matched, and both groups became equivalent. After the matching, the differences in DFS and OS according to MSI/MSS status were estimated to be larger than before (DFS: 63.3% vs 41.4%; P = .002; OS: 65.8% vs 42.5%; P = .002). Regarding patients referred for CMT, there was no difference in DFS and OS between patients with MSI GC who underwent CMT and those who underwent surgery alone (P = .255 and P = .178, respectively). Conclusion Even after controlling for clinicopathological characteristics, MSI was identified as a prognostic factor for patient survival. MSI GC showed no significant survival benefit with the addition of CMT.

Personalized therapy in lung cancer (LC) has revolutionized routine histopathology and cytopathology, emphasizing the importance of obtaining adequate material for molecular studies to support oncological decisions. Adaptations of cytologic sample preparations offer benefits for molecular testing, yet their potential remains underutilized. A significant number of LC cases is identified through specimens of aspiration or exfoliative cytology. Improving screening approaches and optimizing tissue utilization for biomarker research are crucial for effective LC management. The utilization of formalin-fixed, paraffin-embedded (FFPE) tumor tissues has become standard practice in clinical and epidemiological genetic research. However, current techniques require not only a standardized sample fixation and storage but also sufficient genetic material to yield reliable results. In this study, we utilized the Qiagen GeneRead® DNA FFPE kit with an adapted protocol for two extraction methods: one involved cutting FFPE blocks and the other involved scraping tissue from slides used for histochemical and cytological analysis. Our findings emphasized the importance of increasing the number of FFPE sections, heat deparaffinization, and adjusting proteinase K digestion time to enhance genomic DNA (gDNA) yields. Notably, scraping tissue from slides yielded superior results compared to the standard FFPE protocol. A median of 2.82 and 4.34 DNA yields for tumor and lymph node, respectively, were obtained. Our results demonstrated the feasibility of this adapted protocol for gDNA extraction in clinical and epidemiological studies. We recommend scraping tissue from slides as a reliable source of gDNA and suggest fine-tuning proteinase K digestion time and heat exposure based on the input tissue volume.

This case report highlights the diagnostic challenges in distinguishing between metastatic peritoneal mesothelioma with duodenal involvement and synovial sarcoma of the duodenum, two rare and complex entities. A 59-year-old woman presented with nonspecific abdominal symptoms, and imaging revealed a heterogeneous lesion between the right hepatic lobe and duodenum. Endoscopic ultrasound-guided biopsy and subsequent histopathological analysis initially suggested synovial sarcoma, but further examination, including a FISH assay, confirmed the diagnosis of malignant peritoneal mesothelioma. This case underscores the importance of integrating detailed medical history, imaging, and advanced diagnostic techniques to achieve an accurate diagnosis in rare conditions. Early and precise identification of such diseases is crucial for appropriate therapeutic management and has significant implications for patient prognosis.

3547 Background: Activating mutations in the MAPK pathway are predictive biomarkers in mCCR and 50% of patients (pts) present KRAS mutations. There is a large spectrum of molecular aberrations with a lack of data regarding tumor side correlations and their impact on treatment response and overall survival. Methods: Retrospective cohort of mCRC pts and KRAS activating mutations treated between 2019-2022 in a tertiary cancer center in Brazil. KRAS gene was analyzed by next-generation sequencing in tumor tissue samples. Electronic medical records were reviewed with case report forms registered in RedCap software. The primary endpoint was Overall survival (OS), estimated using Kaplan-Meir and compared with the log-rank test. Cox proportional models were applied to estimate hazard ratios (HR). Results: We included 490 patients with a mean age of 59 years (y), mostly male, 51.4%. Primary left-side location was present in 65.5% and liver metastasis in 66.7%. The spectrum of KRAS mutations found were G12D (31.2%), G12V (20.2%), G13D (15.1%), G12C (9.4%), G12A (4.9%), G12S (3.5%), and G12R (2%). First line regimen was 5-FU and Oxaliplatin (mFLOX) in 84.9% (n=388), with a median PFS of 9.2 months (95%CI 7.8 - 11.6) and OS of 21 months (95%CI;19-23) in this group. Treatment related outcomes in first-line therapy at first evaluation were 40% partial response, 20.4% stable disease, 30,9% disease progression and 1.3% complete response. G12S mutation was associated with better PFS 18.62 vs. 8.75m compared with other codon mutations (HR:0.52;95%CI 0.28-0.98) and OS NR vs. 21.58m HR (HR:0.48;95%CI;0.24-0.97). G12R was associated with worse PFS 5.31 vs. 9.90 m (HR:2.2;95%CI;1.09-4.47) and OS 17.89 vs. 21.88m (HR:1.61;0.79-3.24). Sideness was not associated with prolonged response or overall survival right-sided tumors 20.72 vs. vs. left-sided tumors 22.14m (HR:1.04;95%CI;0.82-1.31). Conclusions: Specific mutated codons in the KRAS gene impact PFS and OS independently of primary tumor sidedness. G12S mutation demonstrated an improved OS and PFS. [Table: see text]