Glycolysis in most tumors is upregulated without mitochondrial dysfunction. The switch to aerobic glycolysis followed by the lactate formation is acquired very early in carcinogenesis, even before tumors cells are exposed to hypoxic conditions. Warburg phenotype shows a metabolic signature of 70–80% of human cancers, which results from the interplay between the activation of the oncogene, loss of function of tumors suppressors, altered signaling pathways and interaction with components of the tumors microenvironment, sometimes working together with epigenetic mechanisms. Warburg effect gives a metabolic programmed outlook of cancer cells driving sustained proliferation and accelerating malignant progression. Now, the notion that a cancer patient should avoid sugar stems from the understanding that cancer cells tend to consume glucose (sugar) at a higher rate compared to normal cells. This concept forms the basis of the Warburg effect in oncology which suggests that cancer cells rely heavily on glucose metabolism to support their growth and proliferation. The Warburg effect is a phenomenon observed in cancer cells where they exhibit altered glucose metabolism compared to normal cells. The Warburg effect describes the preference of cancer cells to rely heavily on glycolysis, a process that breaks down glucose to produce energy, even in the presence of adequate oxygen.
Normally, in healthy cells, when oxygen is available, glucose is efficiently metabolized through a process called oxidative phosphorylation, which generates more energy. However, cancer cells exhibit increased glucose uptake and undergo glycolysis, converting glucose into lactate, even in the presence of oxygen (this is wasting energy). This inefficient energy production through glycolysis is the Warburg effect an enhanced, accelerated conversion of glucose to lactate in malignant tumours even in the presence of abundant oxygen.