Introduction: Gastric adenocarcinoma (GA) is one of the most lethal cancers in the world, with great biological heterogeneity between the intestinal and diffuse histological subtypes. Although the FLOT regimen (5-fluorouracil, leucovorin, oxaliplatin and docetaxel) has improved survival in resectable cases, little is known about its molecular and ecological impacts, especially on the tumor microbiome and host gene expression. Objectives: to investigate how neoadjuvant treatment with FLOT affects intestinal and diffuse adenocarcinoma subtypes, as well as the functional interaction between the microbiome and the human transcriptome. Methods: This research was approved by the Research Ethics Committee of Hospital Universitário João de Barros Barreto under CAAE number 47580121.9.0000.5634. Was analyzed 23 tumor samples from GACpatients undergoing FLOT neoadjuvant chemotherapy, classified as diffuse (n = 9) or intestinal (n = 14) subtype according to Lauren's criteria. Human reads were aligned to the GRCh38 reference genome, while non-human reads were classified by taxonomic profiles and microbial gene expression using Kraken2 and later with Salmon. Differential gene expression was assessed with DESeq2, followed by functional analysis and correlations between human and microbial genes. Results: The diffuse subtype showed a much more robust microbial and transcriptomic response to FLOT than the intestinal one. A total of 112 positively and 78 negatively regulated microbial genes were identified in the diffuse group, compared to only 34 in the intestinal group. Species such as Fusobacterium nucleatum and Prevotella intermedia were more abundant in the diffuse subtype, suggesting a microbiome more sensitive to chemotherapy. In the human transcriptome, the diffuse subtype revealed 205 upregulated genes, including MMP1, MMP9, S100A8 AND S100A9, linked to extracellular matrix degradation and inflammation. Gene enrichment analysis indicated processes related to stromal remodeling, leukocyte chemotaxis, angiogenesis, and cytokine-integrin interaction. Correlations between microbial and human genes revealed significant functional interactions. F. nucleatum was associated with immunomodulatory and structural genes, while P. intermedia correlated with angiogenic regulators such as VEGFA and CXCL12. Microbial genes such as cydA, nrdA and gapdh showed co-regulation with human stress response genes, pointing to an integrative response between host and microbiome. Conclusion: FLOT therapy induces a subtype-specific reprogramming of the tumor microenvironment in GA. In diffuse tumors, this involves coordinated shifts in both microbial and host gene expression, including inflammation, angiogenesis, redox regulation, and stromal remodeling. These results underscore the importance of incorporating microbial and molecular profiling into precision oncology, potentially guiding the development of microbiome-based biomarkers and therapeutic targets in gastric cancer.
It is with great enthusiasm that we present the Annals of the Oncology International Symposium 2025, an event that continues to solidify its significance in the oncology landscape of northern Brazil. Held in Belém, Pará, Oncology 2025 centered around the theme "The cancer control challenge: better knowing it to best facing it," dedicating itself to exploring the latest frontiers in cancer treatment and prevention.
This year, the symposium provided a deep dive into the essential role of knowledge in the fight against cancer, presenting new perspectives and scientific advancements across various areas of oncology. Renowned global experts gathered to share their most recent research and innovative approaches, offering participants a comprehensive view of the challenges faced by healthcare professionals and patients worldwide.
Presentations and discussions during the event focused on critical topics such as the use of new technologies, advancements in personalized therapies, and more effective prevention strategies. Additionally, particular attention was given to the unique challenges faced by the Amazon region, with efforts aimed at developing region-specific solutions to meet local needs.
Beyond being a high-caliber academic event, Oncology 2025 stood out as a moment for integration and professional networking, with the warm hospitality of the city of Belém offering participants a unique experience. This event became a platform for exchanging ideas, where science, culture, and humanity came together in pursuit of a common goal: to improve cancer control both in Brazil and globally.
This collection of abstracts and articles presented during the event reflects the ongoing dedication to research and the development of innovative solutions, highlighting the importance of collaboration and shared knowledge in the fight against cancer.
General Submission Guidelines:
The presenting author, who does not have to be the first author, must be registered for Oncology 2025.
Each abstract may have up to 10 authors, including the main author and co-authors.
Only original, unpublished work will be accepted.
Submissions must be related to oncology. However, project descriptions, work proposals, experience reports, and literature reviews will not be considered.
Clinical case reports are allowed, provided the abstract addresses scientific questions, details clinical observations, and includes primary scientific data.
The abstract must be written in English, but presentations may be given in Portuguese.
Abstracts must be between 300 and 500 words.
Comissão Organizadora
Comissão Científica
See Annals of Oncology 2023 at:
https://www.even3.com.br/anais/oncology-2023-international-symposium/
Complete tool for submission, evaluation and publication of proceedings for scientific events.
