Gastric cancer (GC) is a common malignancy globally, ranking fourth in cancer mortality. It is a multifactorial disease influenced by both environmental and genetic factors. The median age of diagnosis is 70 years, though 10% of cases occur in individuals under 45. Early-onset GC is valuable for studying genetic alterations in carcinogenesis. GC development involves multiple stages with progressive mutations and epigenetic changes. The Lauren classification divides GC into intestinal and diffuse subtypes, with the latter being more aggressive. GC incidence varies geographically, with higher rates in developing countries. Risk factors include family history, diet, alcohol, smoking, and Helicobacter pylori (H. pylori) infection. Hereditary diffuse gastric cancer (HDGC), caused by CDH1 mutations, is a familial form of GC. The WHO classification is the most detailed, categorizing GC into subtypes like tubular and signet ring cell carcinoma. GC prevention includes dietary changes, H. pylori eradication, and early detection via endoscopy. Treatment strategies include surgery, adjuvant and neoadjuvant chemotherapy, radiation, and targeted therapies like ramucirumab and trastuzumab. Imaging techniques such as CT, MRI, and PET are used for staging and monitoring. GC remains a significant global health issue, requiring improved prevention, early detection, and personalized treatment approaches.Gastric cancer (GC) is a common malignancy globally, ranking fourth in cancer mortality. It is a multifactorial disease influenced by both environmental and genetic factors. The median age of diagnosis is 70 years, though 10% of cases occur in individuals under 45. Early-onset GC is valuable for studying genetic alterations in carcinogenesis. GC development involves multiple stages with progressive mutations and epigenetic changes. The Lauren classification divides GC into intestinal and diffuse subtypes, with the latter being more aggressive. GC incidence varies geographically, with higher rates in developing countries. Risk factors include family history, diet, alcohol, smoking, and Helicobacter pylori (H. pylori) infection. Hereditary diffuse gastric cancer (HDGC), caused by CDH1 mutations, is a familial form of GC. The WHO classification is the most detailed, categorizing GC into subtypes like tubular and signet ring cell carcinoma. GC prevention includes dietary changes, H. pylori eradication, and early detection via endoscopy. Treatment strategies include surgery, adjuvant and neoadjuvant chemotherapy, radiation, and targeted therapies like ramucirumab and trastuzumab. Imaging techniques such as CT, MRI, and PET are used for staging and monitoring. GC remains a significant global health issue, requiring improved prevention, early detection, and personalized treatment approaches.