Early Ideas about Cancer

Humanity and cancer are old adversaries. The earliest descriptions of the disease appear in ancient Egyptian manuscripts, perhaps some four thousand years old. The author catalogued his experience with many kinds of disease and listed treatments for most of them, noting the variable successes and failures. For one problem, a hard mass contained within the breast of his patient, his list of therapeutic options was painfully short: “There is none.”

The next mention of what we know as cancer occurs in the writings of the great Greek father of western medicine, Hippocrates of Kos, who flourished in the fourth century before our current era. Hippocrates, interested in all facets of human disease, developed one of the first comprehensive theories of how things go wrong. Healthy bodies, he thought, maintained a careful balance between four distinct fluids or “humors” (not meaning funny or amusing, but designating any liquid contained within a living thing). These fluids differed in various characteristics. There was red blood, yellow bile, white phlegm, and a substance Hippocrates called black bile. If the balance of these vital fluids tipped toward an excess of any of them, certain diseases resulted.

It fell to the later Roman physician Claudius Galenus (roughly second century), known to posterity as Galen, to systematize and expand the Hippocratic humoral theory of disease, codifying it into the theory of medicine that would dominate western thinking for a millennium and a half. Galen blamed local accumulations of black bile as the cause of cancer. This black bile supposedly became trapped in certain parts of the body and formed a tumor (swelling) or mass. The fluid nature of the disease meant for Galen that attempts to remove the mass by surgery, which had been tried many times, were bound to be futile, as the unbalanced fluid would simply reaccumulate someplace else.

Why did this idea persuade so many for so long? Like many other ways of thinking, such as the biology of Aristotle and the geocentric astronomy of Ptolemy, the humoral theory of disease had an ancient pedigree, its status as the received wisdom of the ancients unrivaled and unchallenged out of respectful reverence—and the lack of a better idea. The modern cell theory of biology and the related theory of disease are fairly recent, dating just to the middle and later 19th century. Our ancient and medieval forebears simply had no concept that our bodies are composed of countless invisible entities. Humans did not really know about cells at all until Robert Hooke discovered them in 1665 by applying his improved microscope to a piece of cork. Another 200 years elapsed before scientists put the pieces into proper place.

What happened to Galen’s humoral theory, and in particular his link between cancer and black bile? It ran afoul of the evidence, or rather the absence of evidence. The great anatomist Andreas Vesalius of Flanders (16th century), while investigating the human body through direct examination, could readily identify blood and phlegm. He found yellow bile in the liver and gall bladder. He found another clear fluid, lymph, and described the larger channels in which it flows. But of black bile there was nothing. This failure unnerved Vesalius. Who was he to create doubt about Galen’s trustworthiness? Eventually he hushed the matter up by burying his observations in his unpublished papers.

Two hundred years after Vesalius, a British physiologist and anatomist named Matthew Baillie described the appearance of many tumor specimens, not one of which contained anything like black bile. Not only did this ironclad evidence drive the final nail into the black bile theory, it revived efforts to treat tumors with surgery, and most of the cancer treatments for the next century relied on the work of surgeons.

But an explanation for the cause and development of cancer remained elusive.