There are achievements and progressions made in the field of cancer research all the time, but one of the most prominent theories comes from early in the 1900s. In 1931, German physiologist Dr. Otto Heinrich Warburg received the Nobel Prize in Physiology and Medicine for his research involving cancer—specifically, Dr. Warburg studied the respiration of cells and the metabolism of tumors, publishing his findings in The Metabolism of Tumours.
Cells require oxygen to survive, but the main exception to this is cancerous cells. They can live without oxygen. Dr. Warburg determined that depriving a cell of 35 percent of its oxygen for 48 hours could result in it becoming cancerous.
To further his research, Dr. Warburg studied the respiration of cells and metabolism of tumors, finding that cancer cells thrive when they are in a lower pH (as low as 6.0). His belief was that there was a relationship between oxygen and pH; a lower pH is related to lower concentrations of oxygen, while a higher pH is related to a higher concentration of oxygen. The normal level of pH in the body is 7.365.
With excess acidity in the body—or a low pH—an acidic state results, and leads to cancer, according to Dr. Warburg.
Dr. Warburg strongly believed that oxygen deficiency was the root cause of cancer and discovered that cancer cells could not survive with high levels of oxygen.