He hypothesized that cancer, malignant growth, and tumor growth are caused by the fact that tumor cells mainly generate energy (as e.g., adenosine triphosphate / ATP) by non-oxidative breakdown of glucose (a process called glycolysis).
His theory posits that cancer, malignant growth, and tumor development are caused by the primary production of energy in tumor cells via glycolysis, which involves the non-oxidative breakdown of glucose to create ATP.