This chapter examines cancer, the second leading cause of mortality globally, with the statistic that one in two individuals will be diagnosed with cancer at some point in their lives. Cancer can originate from various tissues and organs, resulting in a diverse range of cancer types. The hallmark of cancer across all types is the loss of normal cellular proliferation control, leading to uncontrolled cell division and the formation of primary malignant tumors. These cancerous cells can disseminate throughout the body, potentially leading to life-threatening metastases. Preventive strategies emerge as the most effective means to reduce both the incidence and mortality of cancer. Key interventions include mitigating exposure to carcinogens, such as tobacco smoke, and adopting lifestyle modifications, including a healthy diet and regular physical activity. Such preventive measures also impact late-stage cancer complications, such as cachexia, thereby contributing to improved overall outcomes.