A cancer cell is a cell whose growth controls have broken down through accumulated genetic mutations, causing it to divide uncontrollably and ignore the signals that normally limit proliferation or trigger cell death. As it multiplies it forms a tumour that can invade surrounding tissue and, in malignant cancers, spread to distant sites through blood or lymph. Cancer cells often rewire their metabolism, consuming glucose avidly even with oxygen present. In nutrition, the relationship between diet and cancer involves risk factors such as obesity, alcohol, and processed meat, and supportive care during treatment, though no diet alone cures established disease.