254INSIGHTS INTO GASTRIC CANCER: FROM CELLULAR MECHANISMS TO MARINE ALGAE-DERIVED PHYTOCHEMICALS FOR THERAPYCancer remains a leading cause of global mortality, characterized by uncontrolled cellular proliferation, evasion of apoptosis, and the potential for metastasis. Among various cancer types, gastric cancer (GC) is notably the fifth most prevalent malignancy and the third leading cause of cancer-related deaths worldwide. The multifactorial etiology of GC involves genetic mutations, environmental influences, pathogenic infections, and lifestyle-related factors. Notably, Helicobacter pylori infection plays a pivotal role in the initiation and progression of gastric carcinogenesis through its virulence factors, which disrupt cellular signaling pathways such as PI3K/Akt, JAK/STAT, and Ras/Raf/ERK. Advances in molecular oncology have enabled the classification of gastric cancer into distinct subtypes based on genomic, epigenetic, and phenotypic profiles, offering potential for targeted therapeutic strategies.In parallel, marine-derived bioactive compounds, particularly from red algae species such as Grateloupia, Laurencia, and Gracilaria, have emerged as promising candidates for anticancer therapy. These natural compounds, including sulfated polysaccharides, alkaloids, terpenoids, and polyphenols, have demonstrated the ability to modulate key cancer-related pathways, induce apoptosis, and inhibit tumor metastasis. This review highlights the intricate molecular mechanisms underlying gastric cancer, its epidemiological trends, and the therapeutic potential of marine red algae-derived phytochemicals, underscoring the importance of marine natural products in the development of novel anticancer interventionsmpharm76@gmail.comResearch1512025Gastric cancer, Metastasis, Helicobacter pylori, Molecular mechanisms, Marine red algae, PhytochemicalsDr. Sethuramani A,Vinothini M2, Gunamathi G2, Sebatini Sinsi A2, Muhila M,Rubika Josephine A2Assistant Professor, Department of Pharmacognosy, College of Pharmacy, Madurai Medical College, Madurai, Tamil Nadu, India,Department of Pharmacognosy, College of Pharmacy, Madurai Medical College, Madurai, Tamil Nadu, India.,Department of Pharmacognosy, College of Pharmacy, Madurai Medical College, Madurai, Tamil Nadu, India.