This workshop introduces the foundations of onco-nutrition, cancer biology, risk factors, and the importance of nutritional support throughout cancer care. It covers the hallmarks of cancer, modifiable and non-modifiable risk factors, common warning signs, and the clinical significance of early detection. Participants will learn about cancer staging, grading, metastasis, and the TNM classification system used in clinical practice. The session also provides an overview of diagnostic approaches, including imaging, laboratory investigations, and biopsy. Special emphasis is placed on understanding how disease progression and treatment planning influence nutritional and supportive care.