Different types of cancers tend to metastasize to particular organs, but overall the most common places for metastases to occur are the lungs, liver, brain and the bones. Metabolism
Normal cells typically generate only about 30% of energy from glycolysis, whereas most cancers rely on glycolysis for energy production (Warburg effect). But a minority of cancer types rely on oxidative phosphorylation as the primary energy source, including lymphoma, leukemia, and endometrial cancer. Even in these cases, however, the use of glycolysis as an energy source rarely exceeds 60%. A few cancers use glutamine as the major energy source, partly because it provides nitrogen required for nucleotide (DNA, RNA) synthesis. Cancer stem cells often use oxidative phosphorylation or glutamine as a primary energy source.Several studies have indicated that the enzyme sirtuin 6 is selectively inactivated during oncogenesis in a variety of tumor types by inducing glycolysis. Another sirtuin, sirtuin 3 inhibits cancers that depend upon glycolysis, but promotes cancers that depend upon oxidative phosphorylation.A low-carbohydrate diet (ketogenic diet) has sometimes been recommended as a supportive therapy for cancer treatment. Diagnosis
Most cancers are initially recognized either because of the appearance of signs or symptoms or through screening. Neither of these leads to a definitive diagnosis, which requires the examination of a tissue sample by a pathologist. People with suspected cancer are investigated with medical tests. These commonly include blood tests, X-rays, (contrast) CT scans and endoscopy. The tissue diagnosis from the biopsy indicates the type of cell that is proliferating, its histological grade, genetic abnormalities and other features.
Another 2014 review concluded that vitamin D3 may decrease the risk of death from cancer (one fewer death in 150 people treated over 5 years), but concerns with the quality of the data were noted.Beta-Carotene supplementation increases lung cancer rates in those who are high risk. Folic acid supplementation is not effective in preventing colon cancer and may increase colon polyps. Selenium supplementation has not been shown to reduce the risk of cancer. Vaccination
Vaccines have been developed that prevent infection by some carcinogenic viruses. Human papillomavirus vaccine (Gardasil and Cervarix) decrease the risk of developing cervical cancer. The hepatitis B vaccine prevents infection with hepatitis B virus and thus decreases the risk of liver cancer. The administration of human papillomavirus and hepatitis B vaccinations is recommended where resources allow. Screening
Unlike diagnostic efforts prompted by symptoms and medical signs, cancer screening involves efforts to detect cancer after it has formed, but before any noticeable symptoms appear. This may involve physical examination, blood or urine tests or medical imaging.Cancer screening is not available for many types of cancers. Even when tests are available, they may not be recommended for everyone. Universal screening or mass screening involves screening everyone. Selective screening identifies people who are at higher risk, such as people with a family history. Several factors are considered to determine whether the benefits of screening outweigh the risks and the costs of screening.